/*
* Copyright (c) 2015-2016 The Khronos Group Inc.
* Copyright (c) 2015-2016 Valve Corporation
* Copyright (c) 2015-2016 LunarG, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Author: Jeremy Hayes <jeremy@lunarg.com>
*/

#if defined(VK_USE_PLATFORM_XLIB_KHR) || defined(VK_USE_PLATFORM_XCB_KHR)
#include <X11/Xutil.h>
#elif defined(VK_USE_PLATFORM_WAYLAND_KHR)
#include <linux/input.h>
#endif

#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <csignal>
#include <memory>

#if defined(VK_USE_PLATFORM_MIR_KHR)
#warning "Cubepp does not have code for Mir at this time"
#endif

#define VULKAN_HPP_NO_EXCEPTIONS
#include <vulkan/vulkan.hpp>
#include <vulkan/vk_sdk_platform.h>

#include "linmath.h"

#ifndef NDEBUG
#define VERIFY(x) assert(x)
#else
#define VERIFY(x) ((void)(x))
#endif

#define APP_SHORT_NAME "cube"
#ifdef _WIN32
#define APP_NAME_STR_LEN 80
#endif

// Allow a maximum of two outstanding presentation operations.
#define FRAME_LAG 2

#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))

#ifdef _WIN32
#define ERR_EXIT(err_msg, err_class)                                          \
    do {                                                                      \
        if (!suppress_popups) MessageBox(nullptr, err_msg, err_class, MB_OK); \
        exit(1);                                                              \
    } while (0)
#else
#define ERR_EXIT(err_msg, err_class) \
    do {                             \
        printf("%s\n", err_msg);     \
        fflush(stdout);              \
        exit(1);                     \
    } while (0)
#endif

struct texture_object {
    vk::Sampler sampler;

    vk::Image image;
    vk::ImageLayout imageLayout{vk::ImageLayout::eUndefined};

    vk::MemoryAllocateInfo mem_alloc;
    vk::DeviceMemory mem;
    vk::ImageView view;

    int32_t tex_width{0};
    int32_t tex_height{0};
};

static char const *const tex_files[] = {"lunarg.ppm"};

static int validation_error = 0;

struct vkcube_vs_uniform {
    // Must start with MVP
    float mvp[4][4];
    float position[12 * 3][4];
    float color[12 * 3][4];
};

struct vktexcube_vs_uniform {
    // Must start with MVP
    float mvp[4][4];
    float position[12 * 3][4];
    float attr[12 * 3][4];
};

//--------------------------------------------------------------------------------------
// Mesh and VertexFormat Data
//--------------------------------------------------------------------------------------
// clang-format off
static const float g_vertex_buffer_data[] = {
    -1.0f,-1.0f,-1.0f,  // -X side
    -1.0f,-1.0f, 1.0f,
    -1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f,-1.0f,
    -1.0f,-1.0f,-1.0f,

    -1.0f,-1.0f,-1.0f,  // -Z side
     1.0f, 1.0f,-1.0f,
     1.0f,-1.0f,-1.0f,
    -1.0f,-1.0f,-1.0f,
    -1.0f, 1.0f,-1.0f,
     1.0f, 1.0f,-1.0f,

    -1.0f,-1.0f,-1.0f,  // -Y side
     1.0f,-1.0f,-1.0f,
     1.0f,-1.0f, 1.0f,
    -1.0f,-1.0f,-1.0f,
     1.0f,-1.0f, 1.0f,
    -1.0f,-1.0f, 1.0f,

    -1.0f, 1.0f,-1.0f,  // +Y side
    -1.0f, 1.0f, 1.0f,
     1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f,-1.0f,
     1.0f, 1.0f, 1.0f,
     1.0f, 1.0f,-1.0f,

     1.0f, 1.0f,-1.0f,  // +X side
     1.0f, 1.0f, 1.0f,
     1.0f,-1.0f, 1.0f,
     1.0f,-1.0f, 1.0f,
     1.0f,-1.0f,-1.0f,
     1.0f, 1.0f,-1.0f,

    -1.0f, 1.0f, 1.0f,  // +Z side
    -1.0f,-1.0f, 1.0f,
     1.0f, 1.0f, 1.0f,
    -1.0f,-1.0f, 1.0f,
     1.0f,-1.0f, 1.0f,
     1.0f, 1.0f, 1.0f,
};

static const float g_uv_buffer_data[] = {
    0.0f, 1.0f,  // -X side
    1.0f, 1.0f,
    1.0f, 0.0f,
    1.0f, 0.0f,
    0.0f, 0.0f,
    0.0f, 1.0f,

    1.0f, 1.0f,  // -Z side
    0.0f, 0.0f,
    0.0f, 1.0f,
    1.0f, 1.0f,
    1.0f, 0.0f,
    0.0f, 0.0f,

    1.0f, 0.0f,  // -Y side
    1.0f, 1.0f,
    0.0f, 1.0f,
    1.0f, 0.0f,
    0.0f, 1.0f,
    0.0f, 0.0f,

    1.0f, 0.0f,  // +Y side
    0.0f, 0.0f,
    0.0f, 1.0f,
    1.0f, 0.0f,
    0.0f, 1.0f,
    1.0f, 1.0f,

    1.0f, 0.0f,  // +X side
    0.0f, 0.0f,
    0.0f, 1.0f,
    0.0f, 1.0f,
    1.0f, 1.0f,
    1.0f, 0.0f,

    0.0f, 0.0f,  // +Z side
    0.0f, 1.0f,
    1.0f, 0.0f,
    0.0f, 1.0f,
    1.0f, 1.0f,
    1.0f, 0.0f,
};
// clang-format on

typedef struct {
    vk::Image image;
    vk::CommandBuffer cmd;
    vk::CommandBuffer graphics_to_present_cmd;
    vk::ImageView view;
    vk::Buffer uniform_buffer;
    vk::DeviceMemory uniform_memory;
    vk::Framebuffer framebuffer;
    vk::DescriptorSet descriptor_set;
} SwapchainImageResources;

struct Demo {
    Demo();
    void build_image_ownership_cmd(uint32_t const &);
    vk::Bool32 check_layers(uint32_t, const char *const *, uint32_t, vk::LayerProperties *);
    void cleanup();
    void create_device();
    void destroy_texture_image(texture_object *);
    void draw();
    void draw_build_cmd(vk::CommandBuffer);
    void flush_init_cmd();
    void init(int, char **);
    void init_connection();
    void init_vk();
    void init_vk_swapchain();
    void prepare();
    void prepare_buffers();
    void prepare_cube_data_buffers();
    void prepare_depth();
    void prepare_descriptor_layout();
    void prepare_descriptor_pool();
    void prepare_descriptor_set();
    void prepare_framebuffers();
    vk::ShaderModule prepare_fs();
    void prepare_pipeline();
    void prepare_render_pass();
    vk::ShaderModule prepare_shader_module(const void *, size_t);
    void prepare_texture_image(const char *, texture_object *, vk::ImageTiling, vk::ImageUsageFlags, vk::MemoryPropertyFlags);
    void prepare_textures();
    vk::ShaderModule prepare_vs();
    char *read_spv(const char *, size_t *);
    void resize();
    void set_image_layout(vk::Image, vk::ImageAspectFlags, vk::ImageLayout, vk::ImageLayout, vk::AccessFlags,
                          vk::PipelineStageFlags, vk::PipelineStageFlags);
    void update_data_buffer();
    bool loadTexture(const char *, uint8_t *, vk::SubresourceLayout *, int32_t *, int32_t *);
    bool memory_type_from_properties(uint32_t, vk::MemoryPropertyFlags, uint32_t *);

#if defined(VK_USE_PLATFORM_WIN32_KHR)
    void run();
    void create_window();
#elif defined(VK_USE_PLATFORM_XLIB_KHR)
    void create_xlib_window();
    void handle_xlib_event(const XEvent *);
    void run_xlib();
#elif defined(VK_USE_PLATFORM_XCB_KHR)
    void handle_xcb_event(const xcb_generic_event_t *);
    void run_xcb();
    void create_xcb_window();
#elif defined(VK_USE_PLATFORM_WAYLAND_KHR)
    void run();
    void create_window();
#elif defined(VK_USE_PLATFORM_MIR_KHR)
#elif defined(VK_USE_PLATFORM_DISPLAY_KHR)
    vk::Result create_display_surface();
    void run_display();
#endif

#if defined(VK_USE_PLATFORM_WIN32_KHR)
    HINSTANCE connection;         // hInstance - Windows Instance
    HWND window;                  // hWnd - window handle
    POINT minsize;                // minimum window size
    char name[APP_NAME_STR_LEN];  // Name to put on the window/icon
#elif defined(VK_USE_PLATFORM_XLIB_KHR)
    Window xlib_window;
    Atom xlib_wm_delete_window;
    Display *display;
#elif defined(VK_USE_PLATFORM_XCB_KHR)
    xcb_window_t xcb_window;
    xcb_screen_t *screen;
    xcb_connection_t *connection;
    xcb_intern_atom_reply_t *atom_wm_delete_window;
#elif defined(VK_USE_PLATFORM_WAYLAND_KHR)
    wl_display *display;
    wl_registry *registry;
    wl_compositor *compositor;
    wl_surface *window;
    wl_shell *shell;
    wl_shell_surface *shell_surface;
    wl_seat *seat;
    wl_pointer *pointer;
    wl_keyboard *keyboard;
#elif defined(VK_USE_PLATFORM_MIR_KHR)
#endif

    vk::SurfaceKHR surface;
    bool prepared;
    bool use_staging_buffer;
    bool use_xlib;
    bool separate_present_queue;

    vk::Instance inst;
    vk::PhysicalDevice gpu;
    vk::Device device;
    vk::Queue graphics_queue;
    vk::Queue present_queue;
    uint32_t graphics_queue_family_index;
    uint32_t present_queue_family_index;
    vk::Semaphore image_acquired_semaphores[FRAME_LAG];
    vk::Semaphore draw_complete_semaphores[FRAME_LAG];
    vk::Semaphore image_ownership_semaphores[FRAME_LAG];
    vk::PhysicalDeviceProperties gpu_props;
    std::unique_ptr<vk::QueueFamilyProperties[]> queue_props;
    vk::PhysicalDeviceMemoryProperties memory_properties;

    uint32_t enabled_extension_count;
    uint32_t enabled_layer_count;
    char const *extension_names[64];
    char const *enabled_layers[64];

    uint32_t width;
    uint32_t height;
    vk::Format format;
    vk::ColorSpaceKHR color_space;

    uint32_t swapchainImageCount;
    vk::SwapchainKHR swapchain;
    std::unique_ptr<SwapchainImageResources[]> swapchain_image_resources;
    vk::PresentModeKHR presentMode;
    vk::Fence fences[FRAME_LAG];
    uint32_t frame_index;

    vk::CommandPool cmd_pool;
    vk::CommandPool present_cmd_pool;

    struct {
        vk::Format format;
        vk::Image image;
        vk::MemoryAllocateInfo mem_alloc;
        vk::DeviceMemory mem;
        vk::ImageView view;
    } depth;

    static int32_t const texture_count = 1;
    texture_object textures[texture_count];
    texture_object staging_texture;

    struct {
        vk::Buffer buf;
        vk::MemoryAllocateInfo mem_alloc;
        vk::DeviceMemory mem;
        vk::DescriptorBufferInfo buffer_info;
    } uniform_data;

    vk::CommandBuffer cmd;  // Buffer for initialization commands
    vk::PipelineLayout pipeline_layout;
    vk::DescriptorSetLayout desc_layout;
    vk::PipelineCache pipelineCache;
    vk::RenderPass render_pass;
    vk::Pipeline pipeline;

    mat4x4 projection_matrix;
    mat4x4 view_matrix;
    mat4x4 model_matrix;

    float spin_angle;
    float spin_increment;
    bool pause;

    vk::ShaderModule vert_shader_module;
    vk::ShaderModule frag_shader_module;

    vk::DescriptorPool desc_pool;
    vk::DescriptorSet desc_set;

    std::unique_ptr<vk::Framebuffer[]> framebuffers;

    bool quit;
    uint32_t curFrame;
    uint32_t frameCount;
    bool validate;
    bool use_break;
    bool suppress_popups;

    uint32_t current_buffer;
    uint32_t queue_family_count;
};

#ifdef _WIN32
// MS-Windows event handling function:
LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
#endif

#if defined(VK_USE_PLATFORM_WAYLAND_KHR)
static void handle_ping(void *data, wl_shell_surface *shell_surface, uint32_t serial) {
    wl_shell_surface_pong(shell_surface, serial);
}

static void handle_configure(void *data, wl_shell_surface *shell_surface, uint32_t edges, int32_t width, int32_t height) {}

static void handle_popup_done(void *data, wl_shell_surface *shell_surface) {}

static const wl_shell_surface_listener shell_surface_listener = {handle_ping, handle_configure, handle_popup_done};

static void pointer_handle_enter(void *data, struct wl_pointer *pointer, uint32_t serial, struct wl_surface *surface, wl_fixed_t sx,
                                 wl_fixed_t sy) {}

static void pointer_handle_leave(void *data, struct wl_pointer *pointer, uint32_t serial, struct wl_surface *surface) {}

static void pointer_handle_motion(void *data, struct wl_pointer *pointer, uint32_t time, wl_fixed_t sx, wl_fixed_t sy) {}

static void pointer_handle_button(void *data, struct wl_pointer *wl_pointer, uint32_t serial, uint32_t time, uint32_t button,
                                  uint32_t state) {
    Demo *demo = (Demo *)data;
    if (button == BTN_LEFT && state == WL_POINTER_BUTTON_STATE_PRESSED) {
        wl_shell_surface_move(demo->shell_surface, demo->seat, serial);
    }
}

static void pointer_handle_axis(void *data, struct wl_pointer *wl_pointer, uint32_t time, uint32_t axis, wl_fixed_t value) {}

static const struct wl_pointer_listener pointer_listener = {
    pointer_handle_enter, pointer_handle_leave, pointer_handle_motion, pointer_handle_button, pointer_handle_axis,
};

static void keyboard_handle_keymap(void *data, struct wl_keyboard *keyboard, uint32_t format, int fd, uint32_t size) {}

static void keyboard_handle_enter(void *data, struct wl_keyboard *keyboard, uint32_t serial, struct wl_surface *surface,
                                  struct wl_array *keys) {}

static void keyboard_handle_leave(void *data, struct wl_keyboard *keyboard, uint32_t serial, struct wl_surface *surface) {}

static void keyboard_handle_key(void *data, struct wl_keyboard *keyboard, uint32_t serial, uint32_t time, uint32_t key,
                                uint32_t state) {
    if (state != WL_KEYBOARD_KEY_STATE_RELEASED) return;
    Demo *demo = (Demo *)data;
    switch (key) {
        case KEY_ESC:  // Escape
            demo->quit = true;
            break;
        case KEY_LEFT:  // left arrow key
            demo->spin_angle -= demo->spin_increment;
            break;
        case KEY_RIGHT:  // right arrow key
            demo->spin_angle += demo->spin_increment;
            break;
        case KEY_SPACE:  // space bar
            demo->pause = !demo->pause;
            break;
    }
}

static void keyboard_handle_modifiers(void *data, wl_keyboard *keyboard, uint32_t serial, uint32_t mods_depressed,
                                      uint32_t mods_latched, uint32_t mods_locked, uint32_t group) {}

static const struct wl_keyboard_listener keyboard_listener = {
    keyboard_handle_keymap, keyboard_handle_enter, keyboard_handle_leave, keyboard_handle_key, keyboard_handle_modifiers,
};

static void seat_handle_capabilities(void *data, wl_seat *seat, uint32_t caps) {
    // Subscribe to pointer events
    Demo *demo = (Demo *)data;
    if ((caps & WL_SEAT_CAPABILITY_POINTER) && !demo->pointer) {
        demo->pointer = wl_seat_get_pointer(seat);
        wl_pointer_add_listener(demo->pointer, &pointer_listener, demo);
    } else if (!(caps & WL_SEAT_CAPABILITY_POINTER) && demo->pointer) {
        wl_pointer_destroy(demo->pointer);
        demo->pointer = NULL;
    }
    // Subscribe to keyboard events
    if (caps & WL_SEAT_CAPABILITY_KEYBOARD) {
        demo->keyboard = wl_seat_get_keyboard(seat);
        wl_keyboard_add_listener(demo->keyboard, &keyboard_listener, demo);
    } else if (!(caps & WL_SEAT_CAPABILITY_KEYBOARD)) {
        wl_keyboard_destroy(demo->keyboard);
        demo->keyboard = NULL;
    }
}

static const wl_seat_listener seat_listener = {
    seat_handle_capabilities,
};

static void registry_handle_global(void *data, wl_registry *registry, uint32_t id, const char *interface, uint32_t version) {
    Demo *demo = (Demo *)data;
    // pickup wayland objects when they appear
    if (strcmp(interface, "wl_compositor") == 0) {
        demo->compositor = (wl_compositor *)wl_registry_bind(registry, id, &wl_compositor_interface, 1);
    } else if (strcmp(interface, "wl_shell") == 0) {
        demo->shell = (wl_shell *)wl_registry_bind(registry, id, &wl_shell_interface, 1);
    } else if (strcmp(interface, "wl_seat") == 0) {
        demo->seat = (wl_seat *)wl_registry_bind(registry, id, &wl_seat_interface, 1);
        wl_seat_add_listener(demo->seat, &seat_listener, demo);
    }
}

static void registry_handle_global_remove(void *data, wl_registry *registry, uint32_t name) {}

static const wl_registry_listener registry_listener = {registry_handle_global, registry_handle_global_remove};
#elif defined(VK_USE_PLATFORM_MIR_KHR)
#endif

Demo::Demo()
    :
#if defined(VK_USE_PLATFORM_WIN32_KHR)
      connection{nullptr},
      window{nullptr},
      minsize(POINT{0, 0}),  // Use explicit construction to avoid MSVC error C2797.
#endif

#if defined(VK_USE_PLATFORM_XLIB_KHR)
      xlib_window{0},
      xlib_wm_delete_window{0},
      display{nullptr},
#elif defined(VK_USE_PLATFORM_XCB_KHR)
      xcb_window{0},
      screen{nullptr},
      connection{nullptr},
#elif defined(VK_USE_PLATFORM_WAYLAND_KHR)
      display{nullptr},
      registry{nullptr},
      compositor{nullptr},
      window{nullptr},
      shell{nullptr},
      shell_surface{nullptr},
      seat{nullptr},
      pointer{nullptr},
      keyboard{nullptr},
#elif defined(VK_USE_PLATFORM_MIR_KHR)
#endif
      prepared{false},
      use_staging_buffer{false},
      use_xlib{false},
      graphics_queue_family_index{0},
      present_queue_family_index{0},
      enabled_extension_count{0},
      enabled_layer_count{0},
      width{0},
      height{0},
      swapchainImageCount{0},
      frame_index{0},
      spin_angle{0.0f},
      spin_increment{0.0f},
      pause{false},
      quit{false},
      curFrame{0},
      frameCount{0},
      validate{false},
      use_break{false},
      suppress_popups{false},
      current_buffer{0},
      queue_family_count{0} {
#if defined(VK_USE_PLATFORM_WIN32_KHR)
        memset(name, '\0', APP_NAME_STR_LEN);
#endif
        memset(projection_matrix, 0, sizeof(projection_matrix));
        memset(view_matrix, 0, sizeof(view_matrix));
        memset(model_matrix, 0, sizeof(model_matrix));
    }

    void Demo::build_image_ownership_cmd(uint32_t const &i) {
        auto const cmd_buf_info = vk::CommandBufferBeginInfo().setFlags(vk::CommandBufferUsageFlagBits::eSimultaneousUse);
        auto result = swapchain_image_resources[i].graphics_to_present_cmd.begin(&cmd_buf_info);
        VERIFY(result == vk::Result::eSuccess);

        auto const image_ownership_barrier =
            vk::ImageMemoryBarrier()
                .setSrcAccessMask(vk::AccessFlags())
                .setDstAccessMask(vk::AccessFlagBits::eColorAttachmentWrite)
                .setOldLayout(vk::ImageLayout::ePresentSrcKHR)
                .setNewLayout(vk::ImageLayout::ePresentSrcKHR)
                .setSrcQueueFamilyIndex(graphics_queue_family_index)
                .setDstQueueFamilyIndex(present_queue_family_index)
                .setImage(swapchain_image_resources[i].image)
                .setSubresourceRange(vk::ImageSubresourceRange(vk::ImageAspectFlagBits::eColor, 0, 1, 0, 1));

        swapchain_image_resources[i].graphics_to_present_cmd.pipelineBarrier(
            vk::PipelineStageFlagBits::eColorAttachmentOutput, vk::PipelineStageFlagBits::eColorAttachmentOutput,
            vk::DependencyFlagBits(), 0, nullptr, 0, nullptr, 1, &image_ownership_barrier);

        result = swapchain_image_resources[i].graphics_to_present_cmd.end();
        VERIFY(result == vk::Result::eSuccess);
    }

    vk::Bool32 Demo::check_layers(uint32_t check_count, char const *const *const check_names, uint32_t layer_count,
                                  vk::LayerProperties *layers) {
        for (uint32_t i = 0; i < check_count; i++) {
            vk::Bool32 found = VK_FALSE;
            for (uint32_t j = 0; j < layer_count; j++) {
                if (!strcmp(check_names[i], layers[j].layerName)) {
                    found = VK_TRUE;
                    break;
                }
            }
            if (!found) {
                fprintf(stderr, "Cannot find layer: %s\n", check_names[i]);
                return 0;
            }
        }
        return VK_TRUE;
    }

    void Demo::cleanup() {
        prepared = false;
        device.waitIdle();

        // Wait for fences from present operations
        for (uint32_t i = 0; i < FRAME_LAG; i++) {
            device.waitForFences(1, &fences[i], VK_TRUE, UINT64_MAX);
            device.destroyFence(fences[i], nullptr);
            device.destroySemaphore(image_acquired_semaphores[i], nullptr);
            device.destroySemaphore(draw_complete_semaphores[i], nullptr);
            if (separate_present_queue) {
                device.destroySemaphore(image_ownership_semaphores[i], nullptr);
            }
        }

        for (uint32_t i = 0; i < swapchainImageCount; i++) {
            device.destroyFramebuffer(swapchain_image_resources[i].framebuffer, nullptr);
        }
        device.destroyDescriptorPool(desc_pool, nullptr);

        device.destroyPipeline(pipeline, nullptr);
        device.destroyPipelineCache(pipelineCache, nullptr);
        device.destroyRenderPass(render_pass, nullptr);
        device.destroyPipelineLayout(pipeline_layout, nullptr);
        device.destroyDescriptorSetLayout(desc_layout, nullptr);

        for (uint32_t i = 0; i < texture_count; i++) {
            device.destroyImageView(textures[i].view, nullptr);
            device.destroyImage(textures[i].image, nullptr);
            device.freeMemory(textures[i].mem, nullptr);
            device.destroySampler(textures[i].sampler, nullptr);
        }
        device.destroySwapchainKHR(swapchain, nullptr);

        device.destroyImageView(depth.view, nullptr);
        device.destroyImage(depth.image, nullptr);
        device.freeMemory(depth.mem, nullptr);

        for (uint32_t i = 0; i < swapchainImageCount; i++) {
            device.destroyImageView(swapchain_image_resources[i].view, nullptr);
            device.freeCommandBuffers(cmd_pool, 1, &swapchain_image_resources[i].cmd);
            device.destroyBuffer(swapchain_image_resources[i].uniform_buffer, nullptr);
            device.freeMemory(swapchain_image_resources[i].uniform_memory, nullptr);
        }

        device.destroyCommandPool(cmd_pool, nullptr);

        if (separate_present_queue) {
            device.destroyCommandPool(present_cmd_pool, nullptr);
        }
        device.waitIdle();
        device.destroy(nullptr);
        inst.destroySurfaceKHR(surface, nullptr);

#if defined(VK_USE_PLATFORM_XLIB_KHR)
        XDestroyWindow(display, xlib_window);
        XCloseDisplay(display);
#elif defined(VK_USE_PLATFORM_XCB_KHR)
        xcb_destroy_window(connection, xcb_window);
        xcb_disconnect(connection);
        free(atom_wm_delete_window);
#elif defined(VK_USE_PLATFORM_WAYLAND_KHR)
        wl_keyboard_destroy(keyboard);
        wl_pointer_destroy(pointer);
        wl_seat_destroy(seat);
        wl_shell_surface_destroy(shell_surface);
        wl_surface_destroy(window);
        wl_shell_destroy(shell);
        wl_compositor_destroy(compositor);
        wl_registry_destroy(registry);
        wl_display_disconnect(display);
#elif defined(VK_USE_PLATFORM_MIR_KHR)
#endif

        inst.destroy(nullptr);
    }

    void Demo::create_device() {
        float const priorities[1] = {0.0};

        vk::DeviceQueueCreateInfo queues[2];
        queues[0].setQueueFamilyIndex(graphics_queue_family_index);
        queues[0].setQueueCount(1);
        queues[0].setPQueuePriorities(priorities);

        auto deviceInfo = vk::DeviceCreateInfo()
                              .setQueueCreateInfoCount(1)
                              .setPQueueCreateInfos(queues)
                              .setEnabledLayerCount(0)
                              .setPpEnabledLayerNames(nullptr)
                              .setEnabledExtensionCount(enabled_extension_count)
                              .setPpEnabledExtensionNames((const char *const *)extension_names)
                              .setPEnabledFeatures(nullptr);

        if (separate_present_queue) {
            queues[1].setQueueFamilyIndex(present_queue_family_index);
            queues[1].setQueueCount(1);
            queues[1].setPQueuePriorities(priorities);
            deviceInfo.setQueueCreateInfoCount(2);
        }

        auto result = gpu.createDevice(&deviceInfo, nullptr, &device);
        VERIFY(result == vk::Result::eSuccess);
    }

    void Demo::destroy_texture_image(texture_object *tex_objs) {
        // clean up staging resources
        device.freeMemory(tex_objs->mem, nullptr);
        device.destroyImage(tex_objs->image, nullptr);
    }

    void Demo::draw() {
        // Ensure no more than FRAME_LAG renderings are outstanding
        device.waitForFences(1, &fences[frame_index], VK_TRUE, UINT64_MAX);
        device.resetFences(1, &fences[frame_index]);

        vk::Result result;
        do {
            result = device.acquireNextImageKHR(swapchain, UINT64_MAX, image_acquired_semaphores[frame_index],
                    vk::Fence(), &current_buffer);
            if (result == vk::Result::eErrorOutOfDateKHR) {
                // demo->swapchain is out of date (e.g. the window was resized) and
                // must be recreated:
                resize();
            } else if (result == vk::Result::eSuboptimalKHR) {
                // swapchain is not as optimal as it could be, but the platform's
                // presentation engine will still present the image correctly.
                break;
            } else {
                VERIFY(result == vk::Result::eSuccess);
            }
        } while (result != vk::Result::eSuccess);

        update_data_buffer();

        // Wait for the image acquired semaphore to be signaled to ensure
        // that the image won't be rendered to until the presentation
        // engine has fully released ownership to the application, and it is
        // okay to render to the image.
        vk::PipelineStageFlags const pipe_stage_flags = vk::PipelineStageFlagBits::eColorAttachmentOutput;
        auto const submit_info = vk::SubmitInfo()
                                     .setPWaitDstStageMask(&pipe_stage_flags)
                                     .setWaitSemaphoreCount(1)
                                     .setPWaitSemaphores(&image_acquired_semaphores[frame_index])
                                     .setCommandBufferCount(1)
                                     .setPCommandBuffers(&swapchain_image_resources[current_buffer].cmd)
                                     .setSignalSemaphoreCount(1)
                                     .setPSignalSemaphores(&draw_complete_semaphores[frame_index]);

        result = graphics_queue.submit(1, &submit_info, fences[frame_index]);
        VERIFY(result == vk::Result::eSuccess);

        if (separate_present_queue) {
            // If we are using separate queues, change image ownership to the
            // present queue before presenting, waiting for the draw complete
            // semaphore and signalling the ownership released semaphore when
            // finished
            auto const present_submit_info = vk::SubmitInfo()
                                                 .setPWaitDstStageMask(&pipe_stage_flags)
                                                 .setWaitSemaphoreCount(1)
                                                 .setPWaitSemaphores(&draw_complete_semaphores[frame_index])
                                                 .setCommandBufferCount(1)
                                                 .setPCommandBuffers(&swapchain_image_resources[current_buffer].graphics_to_present_cmd)
                                                 .setSignalSemaphoreCount(1)
                                                 .setPSignalSemaphores(&image_ownership_semaphores[frame_index]);

            result = present_queue.submit(1, &present_submit_info, vk::Fence());
            VERIFY(result == vk::Result::eSuccess);
        }

        // If we are using separate queues we have to wait for image ownership,
        // otherwise wait for draw complete
        auto const presentInfo = vk::PresentInfoKHR()
                                     .setWaitSemaphoreCount(1)
                                     .setPWaitSemaphores(separate_present_queue ? &image_ownership_semaphores[frame_index]
                                                                                : &draw_complete_semaphores[frame_index])
                                     .setSwapchainCount(1)
                                     .setPSwapchains(&swapchain)
                                     .setPImageIndices(&current_buffer);

        result = present_queue.presentKHR(&presentInfo);
        frame_index += 1;
        frame_index %= FRAME_LAG;
        if (result == vk::Result::eErrorOutOfDateKHR) {
            // swapchain is out of date (e.g. the window was resized) and
            // must be recreated:
            resize();
        } else if (result == vk::Result::eSuboptimalKHR) {
            // swapchain is not as optimal as it could be, but the platform's
            // presentation engine will still present the image correctly.
        } else {
            VERIFY(result == vk::Result::eSuccess);
        }
    }

    void Demo::draw_build_cmd(vk::CommandBuffer commandBuffer) {
        auto const commandInfo = vk::CommandBufferBeginInfo().setFlags(vk::CommandBufferUsageFlagBits::eSimultaneousUse);

        vk::ClearValue const clearValues[2] = {vk::ClearColorValue(std::array<float, 4>({{0.2f, 0.2f, 0.2f, 0.2f}})),
                                               vk::ClearDepthStencilValue(1.0f, 0u)};

        auto const passInfo = vk::RenderPassBeginInfo()
                                  .setRenderPass(render_pass)
                                  .setFramebuffer(swapchain_image_resources[current_buffer].framebuffer)
                                  .setRenderArea(vk::Rect2D(vk::Offset2D(0, 0), vk::Extent2D((uint32_t)width, (uint32_t)height)))
                                  .setClearValueCount(2)
                                  .setPClearValues(clearValues);

        auto result = commandBuffer.begin(&commandInfo);
        VERIFY(result == vk::Result::eSuccess);

        commandBuffer.beginRenderPass(&passInfo, vk::SubpassContents::eInline);
        commandBuffer.bindPipeline(vk::PipelineBindPoint::eGraphics, pipeline);
        commandBuffer.bindDescriptorSets(vk::PipelineBindPoint::eGraphics, pipeline_layout, 0, 1, &swapchain_image_resources[current_buffer].descriptor_set, 0, nullptr);

        auto const viewport =
            vk::Viewport().setWidth((float)width).setHeight((float)height).setMinDepth((float)0.0f).setMaxDepth((float)1.0f);
        commandBuffer.setViewport(0, 1, &viewport);

        vk::Rect2D const scissor(vk::Offset2D(0, 0), vk::Extent2D(width, height));
        commandBuffer.setScissor(0, 1, &scissor);
        commandBuffer.draw(12 * 3, 1, 0, 0);
        // Note that ending the renderpass changes the image's layout from
        // COLOR_ATTACHMENT_OPTIMAL to PRESENT_SRC_KHR
        commandBuffer.endRenderPass();

        if (separate_present_queue) {
            // We have to transfer ownership from the graphics queue family to
            // the
            // present queue family to be able to present.  Note that we don't
            // have
            // to transfer from present queue family back to graphics queue
            // family at
            // the start of the next frame because we don't care about the
            // image's
            // contents at that point.
            auto const image_ownership_barrier =
                vk::ImageMemoryBarrier()
                    .setSrcAccessMask(vk::AccessFlags())
                    .setDstAccessMask(vk::AccessFlagBits::eColorAttachmentWrite)
                    .setOldLayout(vk::ImageLayout::ePresentSrcKHR)
                    .setNewLayout(vk::ImageLayout::ePresentSrcKHR)
                    .setSrcQueueFamilyIndex(graphics_queue_family_index)
                    .setDstQueueFamilyIndex(present_queue_family_index)
                    .setImage(swapchain_image_resources[current_buffer].image)
                    .setSubresourceRange(vk::ImageSubresourceRange(vk::ImageAspectFlagBits::eColor, 0, 1, 0, 1));

            commandBuffer.pipelineBarrier(vk::PipelineStageFlagBits::eColorAttachmentOutput,
                                          vk::PipelineStageFlagBits::eBottomOfPipe, vk::DependencyFlagBits(), 0, nullptr, 0,
                                          nullptr, 1, &image_ownership_barrier);
        }

        result = commandBuffer.end();
        VERIFY(result == vk::Result::eSuccess);
    }

    void Demo::flush_init_cmd() {
        // TODO: hmm.
        // This function could get called twice if the texture uses a staging
        // buffer
        // In that case the second call should be ignored
        if (!cmd) {
            return;
        }

        auto result = cmd.end();
        VERIFY(result == vk::Result::eSuccess);

        auto const fenceInfo = vk::FenceCreateInfo();
        vk::Fence fence;
        result = device.createFence(&fenceInfo, nullptr, &fence);
        VERIFY(result == vk::Result::eSuccess);

        vk::CommandBuffer const commandBuffers[] = {cmd};
        auto const submitInfo = vk::SubmitInfo().setCommandBufferCount(1).setPCommandBuffers(commandBuffers);

        result = graphics_queue.submit(1, &submitInfo, fence);
        VERIFY(result == vk::Result::eSuccess);

        result = device.waitForFences(1, &fence, VK_TRUE, UINT64_MAX);
        VERIFY(result == vk::Result::eSuccess);

        device.freeCommandBuffers(cmd_pool, 1, commandBuffers);
        device.destroyFence(fence, nullptr);

        cmd = vk::CommandBuffer();
    }

    void Demo::init(int argc, char **argv) {
        vec3 eye = {0.0f, 3.0f, 5.0f};
        vec3 origin = {0, 0, 0};
        vec3 up = {0.0f, 1.0f, 0.0};

        presentMode = vk::PresentModeKHR::eFifo;
        frameCount = UINT32_MAX;
        use_xlib = false;

        for (int i = 1; i < argc; i++) {
            if (strcmp(argv[i], "--use_staging") == 0) {
                use_staging_buffer = true;
                continue;
            }
            if ((strcmp(argv[i], "--present_mode") == 0) && (i < argc - 1)) {
                presentMode = (vk::PresentModeKHR)atoi(argv[i + 1]);
                i++;
                continue;
            }
            if (strcmp(argv[i], "--break") == 0) {
                use_break = true;
                continue;
            }
            if (strcmp(argv[i], "--validate") == 0) {
                validate = true;
                continue;
            }
            if (strcmp(argv[i], "--xlib") == 0) {
                fprintf(stderr, "--xlib is deprecated and no longer does anything");
                continue;
            }
            if (strcmp(argv[i], "--c") == 0 && frameCount == UINT32_MAX && i < argc - 1 &&
                sscanf(argv[i + 1], "%d", &frameCount) == 1) {
                i++;
                continue;
            }
            if (strcmp(argv[i], "--suppress_popups") == 0) {
                suppress_popups = true;
                continue;
            }

            fprintf(stderr,
                    "Usage:\n  %s [--use_staging] [--validate] [--break] "
                    "[--c <framecount>] [--suppress_popups] [--present_mode <present mode enum>]\n"
                    "VK_PRESENT_MODE_IMMEDIATE_KHR = %d\n"
                    "VK_PRESENT_MODE_MAILBOX_KHR = %d\n"
                    "VK_PRESENT_MODE_FIFO_KHR = %d\n"
                    "VK_PRESENT_MODE_FIFO_RELAXED_KHR = %d\n",
                    APP_SHORT_NAME, VK_PRESENT_MODE_IMMEDIATE_KHR, VK_PRESENT_MODE_MAILBOX_KHR, VK_PRESENT_MODE_FIFO_KHR,
                    VK_PRESENT_MODE_FIFO_RELAXED_KHR);
            fflush(stderr);
            exit(1);
        }

        if (!use_xlib) {
            init_connection();
        }

        init_vk();

        width = 500;
        height = 500;

        spin_angle = 4.0f;
        spin_increment = 0.2f;
        pause = false;

        mat4x4_perspective(projection_matrix, (float)degreesToRadians(45.0f), 1.0f, 0.1f, 100.0f);
        mat4x4_look_at(view_matrix, eye, origin, up);
        mat4x4_identity(model_matrix);

        projection_matrix[1][1] *= -1;  // Flip projection matrix from GL to Vulkan orientation.
    }

    void Demo::init_connection() {
#if defined(VK_USE_PLATFORM_XCB_KHR)
        const xcb_setup_t *setup;
        xcb_screen_iterator_t iter;
        int scr;

        connection = xcb_connect(nullptr, &scr);
        if (xcb_connection_has_error(connection) > 0) {
            printf(
                "Cannot find a compatible Vulkan installable client driver "
                "(ICD).\nExiting ...\n");
            fflush(stdout);
            exit(1);
        }

        setup = xcb_get_setup(connection);
        iter = xcb_setup_roots_iterator(setup);
        while (scr-- > 0) xcb_screen_next(&iter);

        screen = iter.data;
#elif defined(VK_USE_PLATFORM_WAYLAND_KHR)
        display = wl_display_connect(nullptr);

        if (display == nullptr) {
            printf(
                "Cannot find a compatible Vulkan installable client driver "
                "(ICD).\nExiting ...\n");
            fflush(stdout);
            exit(1);
        }

        registry = wl_display_get_registry(display);
        wl_registry_add_listener(registry, &registry_listener, this);
        wl_display_dispatch(display);
#elif defined(VK_USE_PLATFORM_MIR_KHR)
#endif
    }

    void Demo::init_vk() {
        uint32_t instance_extension_count = 0;
        uint32_t instance_layer_count = 0;
        uint32_t validation_layer_count = 0;
        char const *const *instance_validation_layers = nullptr;
        enabled_extension_count = 0;
        enabled_layer_count = 0;

        char const *const instance_validation_layers_alt1[] = {"VK_LAYER_LUNARG_standard_validation"};

        char const *const instance_validation_layers_alt2[] = {
            "VK_LAYER_GOOGLE_threading", "VK_LAYER_LUNARG_parameter_validation", "VK_LAYER_LUNARG_object_tracker",
            "VK_LAYER_LUNARG_core_validation", "VK_LAYER_GOOGLE_unique_objects"};

        // Look for validation layers
        vk::Bool32 validation_found = VK_FALSE;
        if (validate) {
            auto result = vk::enumerateInstanceLayerProperties(&instance_layer_count, nullptr);
            VERIFY(result == vk::Result::eSuccess);

            instance_validation_layers = instance_validation_layers_alt1;
            if (instance_layer_count > 0) {
                std::unique_ptr<vk::LayerProperties[]> instance_layers(new vk::LayerProperties[instance_layer_count]);
                result = vk::enumerateInstanceLayerProperties(&instance_layer_count, instance_layers.get());
                VERIFY(result == vk::Result::eSuccess);

                validation_found = check_layers(ARRAY_SIZE(instance_validation_layers_alt1), instance_validation_layers,
                                                instance_layer_count, instance_layers.get());
                if (validation_found) {
                    enabled_layer_count = ARRAY_SIZE(instance_validation_layers_alt1);
                    enabled_layers[0] = "VK_LAYER_LUNARG_standard_validation";
                    validation_layer_count = 1;
                } else {
                    // use alternative set of validation layers
                    instance_validation_layers = instance_validation_layers_alt2;
                    enabled_layer_count = ARRAY_SIZE(instance_validation_layers_alt2);
                    validation_found = check_layers(ARRAY_SIZE(instance_validation_layers_alt2), instance_validation_layers,
                                                    instance_layer_count, instance_layers.get());
                    validation_layer_count = ARRAY_SIZE(instance_validation_layers_alt2);
                    for (uint32_t i = 0; i < validation_layer_count; i++) {
                        enabled_layers[i] = instance_validation_layers[i];
                    }
                }
            }

            if (!validation_found) {
                ERR_EXIT(
                    "vkEnumerateInstanceLayerProperties failed to find "
                    "required validation layer.\n\n"
                    "Please look at the Getting Started guide for "
                    "additional information.\n",
                    "vkCreateInstance Failure");
            }
        }

        /* Look for instance extensions */
        vk::Bool32 surfaceExtFound = VK_FALSE;
        vk::Bool32 platformSurfaceExtFound = VK_FALSE;
        memset(extension_names, 0, sizeof(extension_names));

        auto result = vk::enumerateInstanceExtensionProperties(nullptr, &instance_extension_count, nullptr);
        VERIFY(result == vk::Result::eSuccess);

        if (instance_extension_count > 0) {
            std::unique_ptr<vk::ExtensionProperties[]> instance_extensions(new vk::ExtensionProperties[instance_extension_count]);
            result = vk::enumerateInstanceExtensionProperties(nullptr, &instance_extension_count, instance_extensions.get());
            VERIFY(result == vk::Result::eSuccess);

            for (uint32_t i = 0; i < instance_extension_count; i++) {
                if (!strcmp(VK_KHR_SURFACE_EXTENSION_NAME, instance_extensions[i].extensionName)) {
                    surfaceExtFound = 1;
                    extension_names[enabled_extension_count++] = VK_KHR_SURFACE_EXTENSION_NAME;
                }
#if defined(VK_USE_PLATFORM_WIN32_KHR)
                if (!strcmp(VK_KHR_WIN32_SURFACE_EXTENSION_NAME, instance_extensions[i].extensionName)) {
                    platformSurfaceExtFound = 1;
                    extension_names[enabled_extension_count++] = VK_KHR_WIN32_SURFACE_EXTENSION_NAME;
                }
#elif defined(VK_USE_PLATFORM_XLIB_KHR)
                if (!strcmp(VK_KHR_XLIB_SURFACE_EXTENSION_NAME, instance_extensions[i].extensionName)) {
                    platformSurfaceExtFound = 1;
                    extension_names[enabled_extension_count++] = VK_KHR_XLIB_SURFACE_EXTENSION_NAME;
                }
#elif defined(VK_USE_PLATFORM_XCB_KHR)
                if (!strcmp(VK_KHR_XCB_SURFACE_EXTENSION_NAME, instance_extensions[i].extensionName)) {
                    platformSurfaceExtFound = 1;
                    extension_names[enabled_extension_count++] = VK_KHR_XCB_SURFACE_EXTENSION_NAME;
                }
#elif defined(VK_USE_PLATFORM_WAYLAND_KHR)
                if (!strcmp(VK_KHR_WAYLAND_SURFACE_EXTENSION_NAME, instance_extensions[i].extensionName)) {
                    platformSurfaceExtFound = 1;
                    extension_names[enabled_extension_count++] = VK_KHR_WAYLAND_SURFACE_EXTENSION_NAME;
                }
#elif defined(VK_USE_PLATFORM_MIR_KHR)
#elif defined(VK_USE_PLATFORM_DISPLAY_KHR)
                if (!strcmp(VK_KHR_DISPLAY_EXTENSION_NAME, instance_extensions[i].extensionName)) {
                    platformSurfaceExtFound = 1;
                    extension_names[enabled_extension_count++] = VK_KHR_DISPLAY_EXTENSION_NAME;
                }

#endif
                assert(enabled_extension_count < 64);
            }
        }

        if (!surfaceExtFound) {
            ERR_EXIT(
                "vkEnumerateInstanceExtensionProperties failed to find "
                "the " VK_KHR_SURFACE_EXTENSION_NAME
                " extension.\n\n"
                "Do you have a compatible Vulkan installable client "
                "driver (ICD) installed?\n"
                "Please look at the Getting Started guide for additional "
                "information.\n",
                "vkCreateInstance Failure");
        }

        if (!platformSurfaceExtFound) {
#if defined(VK_USE_PLATFORM_WIN32_KHR)
            ERR_EXIT(
                "vkEnumerateInstanceExtensionProperties failed to find "
                "the " VK_KHR_WIN32_SURFACE_EXTENSION_NAME
                " extension.\n\n"
                "Do you have a compatible Vulkan installable client "
                "driver (ICD) installed?\n"
                "Please look at the Getting Started guide for additional "
                "information.\n",
                "vkCreateInstance Failure");
#elif defined(VK_USE_PLATFORM_XCB_KHR)
            ERR_EXIT(
                "vkEnumerateInstanceExtensionProperties failed to find "
                "the " VK_KHR_XCB_SURFACE_EXTENSION_NAME
                " extension.\n\n"
                "Do you have a compatible Vulkan installable client "
                "driver (ICD) installed?\n"
                "Please look at the Getting Started guide for additional "
                "information.\n",
                "vkCreateInstance Failure");
#elif defined(VK_USE_PLATFORM_WAYLAND_KHR)
            ERR_EXIT(
                "vkEnumerateInstanceExtensionProperties failed to find "
                "the " VK_KHR_WAYLAND_SURFACE_EXTENSION_NAME
                " extension.\n\n"
                "Do you have a compatible Vulkan installable client "
                "driver (ICD) installed?\n"
                "Please look at the Getting Started guide for additional "
                "information.\n",
                "vkCreateInstance Failure");
#elif defined(VK_USE_PLATFORM_MIR_KHR)
#elif defined(VK_USE_PLATFORM_XLIB_KHR)
            ERR_EXIT(
                "vkEnumerateInstanceExtensionProperties failed to find "
                "the " VK_KHR_XLIB_SURFACE_EXTENSION_NAME
                " extension.\n\n"
                "Do you have a compatible Vulkan installable client "
                "driver (ICD) installed?\n"
                "Please look at the Getting Started guide for additional "
                "information.\n",
                "vkCreateInstance Failure");
#elif defined(VK_USE_PLATFORM_DISPLAY_KHR)
            ERR_EXIT(
                "vkEnumerateInstanceExtensionProperties failed to find "
                "the " VK_KHR_DISPLAY_EXTENSION_NAME
                " extension.\n\n"
                "Do you have a compatible Vulkan installable client "
                "driver (ICD) installed?\n"
                "Please look at the Getting Started guide for additional "
                "information.\n",
                "vkCreateInstance Failure");
#endif
        }
        auto const app = vk::ApplicationInfo()
                             .setPApplicationName(APP_SHORT_NAME)
                             .setApplicationVersion(0)
                             .setPEngineName(APP_SHORT_NAME)
                             .setEngineVersion(0)
                             .setApiVersion(VK_API_VERSION_1_0);
        auto const inst_info = vk::InstanceCreateInfo()
                                   .setPApplicationInfo(&app)
                                   .setEnabledLayerCount(enabled_layer_count)
                                   .setPpEnabledLayerNames(instance_validation_layers)
                                   .setEnabledExtensionCount(enabled_extension_count)
                                   .setPpEnabledExtensionNames(extension_names);

        result = vk::createInstance(&inst_info, nullptr, &inst);
        if (result == vk::Result::eErrorIncompatibleDriver) {
            ERR_EXIT(
                "Cannot find a compatible Vulkan installable client "
                "driver (ICD).\n\n"
                "Please look at the Getting Started guide for additional "
                "information.\n",
                "vkCreateInstance Failure");
        } else if (result == vk::Result::eErrorExtensionNotPresent) {
            ERR_EXIT(
                "Cannot find a specified extension library.\n"
                "Make sure your layers path is set appropriately.\n",
                "vkCreateInstance Failure");
        } else if (result != vk::Result::eSuccess) {
            ERR_EXIT(
                "vkCreateInstance failed.\n\n"
                "Do you have a compatible Vulkan installable client "
                "driver (ICD) installed?\n"
                "Please look at the Getting Started guide for additional "
                "information.\n",
                "vkCreateInstance Failure");
        }

        /* Make initial call to query gpu_count, then second call for gpu info*/
        uint32_t gpu_count;
        result = inst.enumeratePhysicalDevices(&gpu_count, nullptr);
        VERIFY(result == vk::Result::eSuccess);
        assert(gpu_count > 0);

        if (gpu_count > 0) {
            std::unique_ptr<vk::PhysicalDevice[]> physical_devices(new vk::PhysicalDevice[gpu_count]);
            result = inst.enumeratePhysicalDevices(&gpu_count, physical_devices.get());
            VERIFY(result == vk::Result::eSuccess);
            /* For cube demo we just grab the first physical device */
            gpu = physical_devices[0];
        } else {
            ERR_EXIT(
                "vkEnumeratePhysicalDevices reported zero accessible "
                "devices.\n\n"
                "Do you have a compatible Vulkan installable client "
                "driver (ICD) installed?\n"
                "Please look at the Getting Started guide for additional "
                "information.\n",
                "vkEnumeratePhysicalDevices Failure");
        }

        /* Look for device extensions */
        uint32_t device_extension_count = 0;
        vk::Bool32 swapchainExtFound = VK_FALSE;
        enabled_extension_count = 0;
        memset(extension_names, 0, sizeof(extension_names));

        result = gpu.enumerateDeviceExtensionProperties(nullptr, &device_extension_count, nullptr);
        VERIFY(result == vk::Result::eSuccess);

        if (device_extension_count > 0) {
            std::unique_ptr<vk::ExtensionProperties[]> device_extensions(new vk::ExtensionProperties[device_extension_count]);
            result = gpu.enumerateDeviceExtensionProperties(nullptr, &device_extension_count, device_extensions.get());
            VERIFY(result == vk::Result::eSuccess);

            for (uint32_t i = 0; i < device_extension_count; i++) {
                if (!strcmp(VK_KHR_SWAPCHAIN_EXTENSION_NAME, device_extensions[i].extensionName)) {
                    swapchainExtFound = 1;
                    extension_names[enabled_extension_count++] = VK_KHR_SWAPCHAIN_EXTENSION_NAME;
                }
                assert(enabled_extension_count < 64);
            }
        }

        if (!swapchainExtFound) {
            ERR_EXIT(
                "vkEnumerateDeviceExtensionProperties failed to find "
                "the " VK_KHR_SWAPCHAIN_EXTENSION_NAME
                " extension.\n\n"
                "Do you have a compatible Vulkan installable client "
                "driver (ICD) installed?\n"
                "Please look at the Getting Started guide for additional "
                "information.\n",
                "vkCreateInstance Failure");
        }

        gpu.getProperties(&gpu_props);

        /* Call with nullptr data to get count */
        gpu.getQueueFamilyProperties(&queue_family_count, nullptr);
        assert(queue_family_count >= 1);

        queue_props.reset(new vk::QueueFamilyProperties[queue_family_count]);
        gpu.getQueueFamilyProperties(&queue_family_count, queue_props.get());

        // Query fine-grained feature support for this device.
        //  If app has specific feature requirements it should check supported
        //  features based on this query
        vk::PhysicalDeviceFeatures physDevFeatures;
        gpu.getFeatures(&physDevFeatures);
    }

    void Demo::init_vk_swapchain() {
    // Create a WSI surface for the window:
#if defined(VK_USE_PLATFORM_WIN32_KHR)
        {
            auto const createInfo = vk::Win32SurfaceCreateInfoKHR().setHinstance(connection).setHwnd(window);

            auto result = inst.createWin32SurfaceKHR(&createInfo, nullptr, &surface);
            VERIFY(result == vk::Result::eSuccess);
        }
#elif defined(VK_USE_PLATFORM_WAYLAND_KHR)
        {
            auto const createInfo = vk::WaylandSurfaceCreateInfoKHR().setDisplay(display).setSurface(window);

            auto result = inst.createWaylandSurfaceKHR(&createInfo, nullptr, &surface);
            VERIFY(result == vk::Result::eSuccess);
        }
#elif defined(VK_USE_PLATFORM_MIR_KHR)
#elif defined(VK_USE_PLATFORM_XLIB_KHR)
        {
            auto const createInfo = vk::XlibSurfaceCreateInfoKHR().setDpy(display).setWindow(xlib_window);

            auto result = inst.createXlibSurfaceKHR(&createInfo, nullptr, &surface);
            VERIFY(result == vk::Result::eSuccess);
        }
#elif defined(VK_USE_PLATFORM_XCB_KHR)
        {
            auto const createInfo = vk::XcbSurfaceCreateInfoKHR().setConnection(connection).setWindow(xcb_window);

            auto result = inst.createXcbSurfaceKHR(&createInfo, nullptr, &surface);
            VERIFY(result == vk::Result::eSuccess);
        }
#elif defined(VK_USE_PLATFORM_DISPLAY_KHR)
        {
            auto result = create_display_surface();
            VERIFY(result == vk::Result::eSuccess);
        }
#endif
        // Iterate over each queue to learn whether it supports presenting:
        std::unique_ptr<vk::Bool32[]> supportsPresent(new vk::Bool32[queue_family_count]);
        for (uint32_t i = 0; i < queue_family_count; i++) {
            gpu.getSurfaceSupportKHR(i, surface, &supportsPresent[i]);
        }

        uint32_t graphicsQueueFamilyIndex = UINT32_MAX;
        uint32_t presentQueueFamilyIndex = UINT32_MAX;
        for (uint32_t i = 0; i < queue_family_count; i++) {
            if (queue_props[i].queueFlags & vk::QueueFlagBits::eGraphics) {
                if (graphicsQueueFamilyIndex == UINT32_MAX) {
                    graphicsQueueFamilyIndex = i;
                }

                if (supportsPresent[i] == VK_TRUE) {
                    graphicsQueueFamilyIndex = i;
                    presentQueueFamilyIndex = i;
                    break;
                }
            }
        }

        if (presentQueueFamilyIndex == UINT32_MAX) {
            // If didn't find a queue that supports both graphics and present,
            // then
            // find a separate present queue.
            for (uint32_t i = 0; i < queue_family_count; ++i) {
                if (supportsPresent[i] == VK_TRUE) {
                    presentQueueFamilyIndex = i;
                    break;
                }
            }
        }

        // Generate error if could not find both a graphics and a present queue
        if (graphicsQueueFamilyIndex == UINT32_MAX || presentQueueFamilyIndex == UINT32_MAX) {
            ERR_EXIT("Could not find both graphics and present queues\n", "Swapchain Initialization Failure");
        }

        graphics_queue_family_index = graphicsQueueFamilyIndex;
        present_queue_family_index = presentQueueFamilyIndex;
        separate_present_queue = (graphics_queue_family_index != present_queue_family_index);

        create_device();

        device.getQueue(graphics_queue_family_index, 0, &graphics_queue);
        if (!separate_present_queue) {
            present_queue = graphics_queue;
        } else {
            device.getQueue(present_queue_family_index, 0, &present_queue);
        }

        // Get the list of VkFormat's that are supported:
        uint32_t formatCount;
        auto result = gpu.getSurfaceFormatsKHR(surface, &formatCount, nullptr);
        VERIFY(result == vk::Result::eSuccess);

        std::unique_ptr<vk::SurfaceFormatKHR[]> surfFormats(new vk::SurfaceFormatKHR[formatCount]);
        result = gpu.getSurfaceFormatsKHR(surface, &formatCount, surfFormats.get());
        VERIFY(result == vk::Result::eSuccess);

        // If the format list includes just one entry of VK_FORMAT_UNDEFINED,
        // the surface has no preferred format.  Otherwise, at least one
        // supported format will be returned.
        if (formatCount == 1 && surfFormats[0].format == vk::Format::eUndefined) {
            format = vk::Format::eB8G8R8A8Unorm;
        } else {
            assert(formatCount >= 1);
            format = surfFormats[0].format;
        }
        color_space = surfFormats[0].colorSpace;

        quit = false;
        curFrame = 0;

        // Create semaphores to synchronize acquiring presentable buffers before
        // rendering and waiting for drawing to be complete before presenting
        auto const semaphoreCreateInfo = vk::SemaphoreCreateInfo();

        // Create fences that we can use to throttle if we get too far
        // ahead of the image presents
        auto const fence_ci = vk::FenceCreateInfo().setFlags(vk::FenceCreateFlagBits::eSignaled);
        for (uint32_t i = 0; i < FRAME_LAG; i++) {
            result = device.createFence(&fence_ci, nullptr, &fences[i]);
            VERIFY(result == vk::Result::eSuccess);

            result = device.createSemaphore(&semaphoreCreateInfo, nullptr, &image_acquired_semaphores[i]);
            VERIFY(result == vk::Result::eSuccess);

            result = device.createSemaphore(&semaphoreCreateInfo, nullptr, &draw_complete_semaphores[i]);
            VERIFY(result == vk::Result::eSuccess);

            if (separate_present_queue) {
                result = device.createSemaphore(&semaphoreCreateInfo, nullptr, &image_ownership_semaphores[i]);
                VERIFY(result == vk::Result::eSuccess);
            }
        }
        frame_index = 0;

        // Get Memory information and properties
        gpu.getMemoryProperties(&memory_properties);
    }

    void Demo::prepare() {
        auto const cmd_pool_info = vk::CommandPoolCreateInfo().setQueueFamilyIndex(graphics_queue_family_index);
        auto result = device.createCommandPool(&cmd_pool_info, nullptr, &cmd_pool);
        VERIFY(result == vk::Result::eSuccess);

        auto const cmd = vk::CommandBufferAllocateInfo()
                             .setCommandPool(cmd_pool)
                             .setLevel(vk::CommandBufferLevel::ePrimary)
                             .setCommandBufferCount(1);

        result = device.allocateCommandBuffers(&cmd, &this->cmd);
        VERIFY(result == vk::Result::eSuccess);

        auto const cmd_buf_info = vk::CommandBufferBeginInfo().setPInheritanceInfo(nullptr);

        result = this->cmd.begin(&cmd_buf_info);
        VERIFY(result == vk::Result::eSuccess);

        prepare_buffers();
        prepare_depth();
        prepare_textures();
        prepare_cube_data_buffers();

        prepare_descriptor_layout();
        prepare_render_pass();
        prepare_pipeline();

        for (uint32_t i = 0; i < swapchainImageCount; ++i) {
            result = device.allocateCommandBuffers(&cmd, &swapchain_image_resources[i].cmd);
            VERIFY(result == vk::Result::eSuccess);
        }

        if (separate_present_queue) {
            auto const present_cmd_pool_info = vk::CommandPoolCreateInfo().setQueueFamilyIndex(present_queue_family_index);

            result = device.createCommandPool(&present_cmd_pool_info, nullptr, &present_cmd_pool);
            VERIFY(result == vk::Result::eSuccess);

            auto const present_cmd = vk::CommandBufferAllocateInfo()
                                         .setCommandPool(present_cmd_pool)
                                         .setLevel(vk::CommandBufferLevel::ePrimary)
                                         .setCommandBufferCount(1);

            for (uint32_t i = 0; i < swapchainImageCount; i++) {
                result = device.allocateCommandBuffers(&present_cmd, &swapchain_image_resources[i].graphics_to_present_cmd);
                VERIFY(result == vk::Result::eSuccess);

                build_image_ownership_cmd(i);
            }
        }

        prepare_descriptor_pool();
        prepare_descriptor_set();

        prepare_framebuffers();

        for (uint32_t i = 0; i < swapchainImageCount; ++i) {
            current_buffer = i;
            draw_build_cmd(swapchain_image_resources[i].cmd);
        }

        /*
         * Prepare functions above may generate pipeline commands
         * that need to be flushed before beginning the render loop.
         */
        flush_init_cmd();
        if (staging_texture.image) {
            destroy_texture_image(&staging_texture);
        }

        current_buffer = 0;
        prepared = true;
    }

    void Demo::prepare_buffers() {
        vk::SwapchainKHR oldSwapchain = swapchain;

        // Check the surface capabilities and formats
        vk::SurfaceCapabilitiesKHR surfCapabilities;
        auto result = gpu.getSurfaceCapabilitiesKHR(surface, &surfCapabilities);
        VERIFY(result == vk::Result::eSuccess);

        uint32_t presentModeCount;
        result = gpu.getSurfacePresentModesKHR(surface, &presentModeCount, nullptr);
        VERIFY(result == vk::Result::eSuccess);

        std::unique_ptr<vk::PresentModeKHR[]> presentModes(new vk::PresentModeKHR[presentModeCount]);
        result = gpu.getSurfacePresentModesKHR(surface, &presentModeCount, presentModes.get());
        VERIFY(result == vk::Result::eSuccess);

        vk::Extent2D swapchainExtent;
        // width and height are either both -1, or both not -1.
        if (surfCapabilities.currentExtent.width == (uint32_t)-1) {
            // If the surface size is undefined, the size is set to
            // the size of the images requested.
            swapchainExtent.width = width;
            swapchainExtent.height = height;
        } else {
            // If the surface size is defined, the swap chain size must match
            swapchainExtent = surfCapabilities.currentExtent;
            width = surfCapabilities.currentExtent.width;
            height = surfCapabilities.currentExtent.height;
        }

        // The FIFO present mode is guaranteed by the spec to be supported
        // and to have no tearing.  It's a great default present mode to use.
        vk::PresentModeKHR swapchainPresentMode = vk::PresentModeKHR::eFifo;

        //  There are times when you may wish to use another present mode.  The
        //  following code shows how to select them, and the comments provide some
        //  reasons you may wish to use them.
        //
        // It should be noted that Vulkan 1.0 doesn't provide a method for
        // synchronizing rendering with the presentation engine's display.  There
        // is a method provided for throttling rendering with the display, but
        // there are some presentation engines for which this method will not work.
        // If an application doesn't throttle its rendering, and if it renders much
        // faster than the refresh rate of the display, this can waste power on
        // mobile devices.  That is because power is being spent rendering images
        // that may never be seen.

        // VK_PRESENT_MODE_IMMEDIATE_KHR is for applications that don't care
        // about
        // tearing, or have some way of synchronizing their rendering with the
        // display.
        // VK_PRESENT_MODE_MAILBOX_KHR may be useful for applications that
        // generally render a new presentable image every refresh cycle, but are
        // occasionally early.  In this case, the application wants the new
        // image
        // to be displayed instead of the previously-queued-for-presentation
        // image
        // that has not yet been displayed.
        // VK_PRESENT_MODE_FIFO_RELAXED_KHR is for applications that generally
        // render a new presentable image every refresh cycle, but are
        // occasionally
        // late.  In this case (perhaps because of stuttering/latency concerns),
        // the application wants the late image to be immediately displayed,
        // even
        // though that may mean some tearing.

        if (presentMode != swapchainPresentMode) {
            for (size_t i = 0; i < presentModeCount; ++i) {
                if (presentModes[i] == presentMode) {
                    swapchainPresentMode = presentMode;
                    break;
                }
            }
        }

        if (swapchainPresentMode != presentMode) {
            ERR_EXIT("Present mode specified is not supported\n", "Present mode unsupported");
        }

        // Determine the number of VkImages to use in the swap chain.
        // Application desires to acquire 3 images at a time for triple
        // buffering
        uint32_t desiredNumOfSwapchainImages = 3;
        if (desiredNumOfSwapchainImages < surfCapabilities.minImageCount) {
            desiredNumOfSwapchainImages = surfCapabilities.minImageCount;
        }

        // If maxImageCount is 0, we can ask for as many images as we want,
        // otherwise
        // we're limited to maxImageCount
        if ((surfCapabilities.maxImageCount > 0) && (desiredNumOfSwapchainImages > surfCapabilities.maxImageCount)) {
            // Application must settle for fewer images than desired:
            desiredNumOfSwapchainImages = surfCapabilities.maxImageCount;
        }

        vk::SurfaceTransformFlagBitsKHR preTransform;
        if (surfCapabilities.supportedTransforms & vk::SurfaceTransformFlagBitsKHR::eIdentity) {
            preTransform = vk::SurfaceTransformFlagBitsKHR::eIdentity;
        } else {
            preTransform = surfCapabilities.currentTransform;
        }

        // Find a supported composite alpha mode - one of these is guaranteed to be set
        vk::CompositeAlphaFlagBitsKHR compositeAlpha = vk::CompositeAlphaFlagBitsKHR::eOpaque;
        vk::CompositeAlphaFlagBitsKHR compositeAlphaFlags[4] = {
            vk::CompositeAlphaFlagBitsKHR::eOpaque,
            vk::CompositeAlphaFlagBitsKHR::ePreMultiplied,
            vk::CompositeAlphaFlagBitsKHR::ePostMultiplied,
            vk::CompositeAlphaFlagBitsKHR::eInherit,
        };
        for (uint32_t i = 0; i < sizeof(compositeAlphaFlags); i++) {
            if (surfCapabilities.supportedCompositeAlpha & compositeAlphaFlags[i]) {
                compositeAlpha = compositeAlphaFlags[i];
                break;
            }
        }

        auto const swapchain_ci = vk::SwapchainCreateInfoKHR()
                                      .setSurface(surface)
                                      .setMinImageCount(desiredNumOfSwapchainImages)
                                      .setImageFormat(format)
                                      .setImageColorSpace(color_space)
                                      .setImageExtent({swapchainExtent.width, swapchainExtent.height})
                                      .setImageArrayLayers(1)
                                      .setImageUsage(vk::ImageUsageFlagBits::eColorAttachment)
                                      .setImageSharingMode(vk::SharingMode::eExclusive)
                                      .setQueueFamilyIndexCount(0)
                                      .setPQueueFamilyIndices(nullptr)
                                      .setPreTransform(preTransform)
                                      .setCompositeAlpha(compositeAlpha)
                                      .setPresentMode(swapchainPresentMode)
                                      .setClipped(true)
                                      .setOldSwapchain(oldSwapchain);

        result = device.createSwapchainKHR(&swapchain_ci, nullptr, &swapchain);
        VERIFY(result == vk::Result::eSuccess);

        // If we just re-created an existing swapchain, we should destroy the
        // old
        // swapchain at this point.
        // Note: destroying the swapchain also cleans up all its associated
        // presentable images once the platform is done with them.
        if (oldSwapchain) {
            device.destroySwapchainKHR(oldSwapchain, nullptr);
        }

        result = device.getSwapchainImagesKHR(swapchain, &swapchainImageCount, nullptr);
        VERIFY(result == vk::Result::eSuccess);

        std::unique_ptr<vk::Image[]> swapchainImages(new vk::Image[swapchainImageCount]);
        result = device.getSwapchainImagesKHR(swapchain, &swapchainImageCount, swapchainImages.get());
        VERIFY(result == vk::Result::eSuccess);

        swapchain_image_resources.reset(new SwapchainImageResources[swapchainImageCount]);

        for (uint32_t i = 0; i < swapchainImageCount; ++i) {
            auto color_image_view =
                vk::ImageViewCreateInfo()
                    .setViewType(vk::ImageViewType::e2D)
                    .setFormat(format)
                    .setSubresourceRange(vk::ImageSubresourceRange(vk::ImageAspectFlagBits::eColor, 0, 1, 0, 1));

            swapchain_image_resources[i].image = swapchainImages[i];

            color_image_view.image = swapchain_image_resources[i].image;

            result = device.createImageView(&color_image_view, nullptr, &swapchain_image_resources[i].view);
            VERIFY(result == vk::Result::eSuccess);
        }
    }

    void Demo::prepare_cube_data_buffers() {
        mat4x4 VP;
        mat4x4_mul(VP, projection_matrix, view_matrix);

        mat4x4 MVP;
        mat4x4_mul(MVP, VP, model_matrix);

        vktexcube_vs_uniform data;
        memcpy(data.mvp, MVP, sizeof(MVP));
        //    dumpMatrix("MVP", MVP)

        for (int32_t i = 0; i < 12 * 3; i++) {
            data.position[i][0] = g_vertex_buffer_data[i * 3];
            data.position[i][1] = g_vertex_buffer_data[i * 3 + 1];
            data.position[i][2] = g_vertex_buffer_data[i * 3 + 2];
            data.position[i][3] = 1.0f;
            data.attr[i][0] = g_uv_buffer_data[2 * i];
            data.attr[i][1] = g_uv_buffer_data[2 * i + 1];
            data.attr[i][2] = 0;
            data.attr[i][3] = 0;
        }

        auto const buf_info = vk::BufferCreateInfo().setSize(sizeof(data)).setUsage(vk::BufferUsageFlagBits::eUniformBuffer);

        for (unsigned int i = 0; i < swapchainImageCount; i++) {
            auto result = device.createBuffer(&buf_info, nullptr, &swapchain_image_resources[i].uniform_buffer);
            VERIFY(result == vk::Result::eSuccess);

            vk::MemoryRequirements mem_reqs;
            device.getBufferMemoryRequirements(swapchain_image_resources[i].uniform_buffer, &mem_reqs);

            auto mem_alloc = vk::MemoryAllocateInfo().setAllocationSize(mem_reqs.size).setMemoryTypeIndex(0);

            bool const pass = memory_type_from_properties(
                mem_reqs.memoryTypeBits, vk::MemoryPropertyFlagBits::eHostVisible | vk::MemoryPropertyFlagBits::eHostCoherent,
                &mem_alloc.memoryTypeIndex);
            VERIFY(pass);

            result = device.allocateMemory(&mem_alloc, nullptr, &swapchain_image_resources[i].uniform_memory);
            VERIFY(result == vk::Result::eSuccess);

            auto pData = device.mapMemory(swapchain_image_resources[i].uniform_memory, 0, VK_WHOLE_SIZE, vk::MemoryMapFlags());
            VERIFY(pData.result == vk::Result::eSuccess);

            memcpy(pData.value, &data, sizeof data);

            device.unmapMemory(swapchain_image_resources[i].uniform_memory);

            result = device.bindBufferMemory(swapchain_image_resources[i].uniform_buffer, swapchain_image_resources[i].uniform_memory, 0);
            VERIFY(result == vk::Result::eSuccess);
        }
    }

    void Demo::prepare_depth() {
        depth.format = vk::Format::eD16Unorm;

        auto const image = vk::ImageCreateInfo()
                               .setImageType(vk::ImageType::e2D)
                               .setFormat(depth.format)
                               .setExtent({(uint32_t)width, (uint32_t)height, 1})
                               .setMipLevels(1)
                               .setArrayLayers(1)
                               .setSamples(vk::SampleCountFlagBits::e1)
                               .setTiling(vk::ImageTiling::eOptimal)
                               .setUsage(vk::ImageUsageFlagBits::eDepthStencilAttachment)
                               .setSharingMode(vk::SharingMode::eExclusive)
                               .setQueueFamilyIndexCount(0)
                               .setPQueueFamilyIndices(nullptr)
                               .setInitialLayout(vk::ImageLayout::eUndefined);

        auto result = device.createImage(&image, nullptr, &depth.image);
        VERIFY(result == vk::Result::eSuccess);

        vk::MemoryRequirements mem_reqs;
        device.getImageMemoryRequirements(depth.image, &mem_reqs);

        depth.mem_alloc.setAllocationSize(mem_reqs.size);
        depth.mem_alloc.setMemoryTypeIndex(0);

        auto const pass = memory_type_from_properties(mem_reqs.memoryTypeBits, vk::MemoryPropertyFlagBits::eDeviceLocal,
                                                      &depth.mem_alloc.memoryTypeIndex);
        VERIFY(pass);

        result = device.allocateMemory(&depth.mem_alloc, nullptr, &depth.mem);
        VERIFY(result == vk::Result::eSuccess);

        result = device.bindImageMemory(depth.image, depth.mem, 0);
        VERIFY(result == vk::Result::eSuccess);

        auto const view = vk::ImageViewCreateInfo()
                              .setImage(depth.image)
                              .setViewType(vk::ImageViewType::e2D)
                              .setFormat(depth.format)
                              .setSubresourceRange(vk::ImageSubresourceRange(vk::ImageAspectFlagBits::eDepth, 0, 1, 0, 1));
        result = device.createImageView(&view, nullptr, &depth.view);
        VERIFY(result == vk::Result::eSuccess);
    }

    void Demo::prepare_descriptor_layout() {
        vk::DescriptorSetLayoutBinding const layout_bindings[2] = {vk::DescriptorSetLayoutBinding()
                                                                       .setBinding(0)
                                                                       .setDescriptorType(vk::DescriptorType::eUniformBuffer)
                                                                       .setDescriptorCount(1)
                                                                       .setStageFlags(vk::ShaderStageFlagBits::eVertex)
                                                                       .setPImmutableSamplers(nullptr),
                                                                   vk::DescriptorSetLayoutBinding()
                                                                       .setBinding(1)
                                                                       .setDescriptorType(vk::DescriptorType::eCombinedImageSampler)
                                                                       .setDescriptorCount(texture_count)
                                                                       .setStageFlags(vk::ShaderStageFlagBits::eFragment)
                                                                       .setPImmutableSamplers(nullptr)};

        auto const descriptor_layout = vk::DescriptorSetLayoutCreateInfo().setBindingCount(2).setPBindings(layout_bindings);

        auto result = device.createDescriptorSetLayout(&descriptor_layout, nullptr, &desc_layout);
        VERIFY(result == vk::Result::eSuccess);

        auto const pPipelineLayoutCreateInfo = vk::PipelineLayoutCreateInfo().setSetLayoutCount(1).setPSetLayouts(&desc_layout);

        result = device.createPipelineLayout(&pPipelineLayoutCreateInfo, nullptr, &pipeline_layout);
        VERIFY(result == vk::Result::eSuccess);
    }

    void Demo::prepare_descriptor_pool() {
        vk::DescriptorPoolSize const poolSizes[2] = {
            vk::DescriptorPoolSize().setType(vk::DescriptorType::eUniformBuffer).setDescriptorCount(swapchainImageCount),
            vk::DescriptorPoolSize().setType(vk::DescriptorType::eCombinedImageSampler).setDescriptorCount(swapchainImageCount * texture_count)};

        auto const descriptor_pool = vk::DescriptorPoolCreateInfo().setMaxSets(swapchainImageCount).setPoolSizeCount(2).setPPoolSizes(poolSizes);

        auto result = device.createDescriptorPool(&descriptor_pool, nullptr, &desc_pool);
        VERIFY(result == vk::Result::eSuccess);
    }

    void Demo::prepare_descriptor_set() {
        auto const alloc_info =
            vk::DescriptorSetAllocateInfo().setDescriptorPool(desc_pool).setDescriptorSetCount(1).setPSetLayouts(&desc_layout);

        auto buffer_info = vk::DescriptorBufferInfo().setOffset(0).setRange(sizeof(struct vktexcube_vs_uniform));

        vk::DescriptorImageInfo tex_descs[texture_count];
        for (uint32_t i = 0; i < texture_count; i++) {
            tex_descs[i].setSampler(textures[i].sampler);
            tex_descs[i].setImageView(textures[i].view);
            tex_descs[i].setImageLayout(vk::ImageLayout::eGeneral);
        }

        vk::WriteDescriptorSet writes[2];

        writes[0].setDescriptorCount(1);
        writes[0].setDescriptorType(vk::DescriptorType::eUniformBuffer);
        writes[0].setPBufferInfo(&buffer_info);

        writes[1].setDstBinding(1);
        writes[1].setDescriptorCount(texture_count);
        writes[1].setDescriptorType(vk::DescriptorType::eCombinedImageSampler);
        writes[1].setPImageInfo(tex_descs);

        for (unsigned int i = 0; i < swapchainImageCount; i++) {
            auto result = device.allocateDescriptorSets(&alloc_info, &swapchain_image_resources[i].descriptor_set);
            VERIFY(result == vk::Result::eSuccess);

            buffer_info.setBuffer(swapchain_image_resources[i].uniform_buffer);
            writes[0].setDstSet(swapchain_image_resources[i].descriptor_set);
            writes[1].setDstSet(swapchain_image_resources[i].descriptor_set);
            device.updateDescriptorSets(2, writes, 0, nullptr);
        }
    }

    void Demo::prepare_framebuffers() {
        vk::ImageView attachments[2];
        attachments[1] = depth.view;

        auto const fb_info = vk::FramebufferCreateInfo()
                                 .setRenderPass(render_pass)
                                 .setAttachmentCount(2)
                                 .setPAttachments(attachments)
                                 .setWidth((uint32_t)width)
                                 .setHeight((uint32_t)height)
                                 .setLayers(1);

        for (uint32_t i = 0; i < swapchainImageCount; i++) {
            attachments[0] = swapchain_image_resources[i].view;
            auto const result = device.createFramebuffer(&fb_info, nullptr, &swapchain_image_resources[i].framebuffer);
            VERIFY(result == vk::Result::eSuccess);
        }
    }

    vk::ShaderModule Demo::prepare_fs() {
        size_t size = 0;
        void *fragShaderCode = read_spv("cube-frag.spv", &size);
        if (!fragShaderCode) {
            ERR_EXIT("Failed to load cube-frag.spv", "Load Shader Failure");
        }

        frag_shader_module = prepare_shader_module(fragShaderCode, size);

        free(fragShaderCode);

        return frag_shader_module;
    }

    void Demo::prepare_pipeline() {
        vk::PipelineCacheCreateInfo const pipelineCacheInfo;
        auto result = device.createPipelineCache(&pipelineCacheInfo, nullptr, &pipelineCache);
        VERIFY(result == vk::Result::eSuccess);

        vk::PipelineShaderStageCreateInfo const shaderStageInfo[2] = {
            vk::PipelineShaderStageCreateInfo().setStage(vk::ShaderStageFlagBits::eVertex).setModule(prepare_vs()).setPName("main"),
            vk::PipelineShaderStageCreateInfo()
                .setStage(vk::ShaderStageFlagBits::eFragment)
                .setModule(prepare_fs())
                .setPName("main")};

        vk::PipelineVertexInputStateCreateInfo const vertexInputInfo;

        auto const inputAssemblyInfo = vk::PipelineInputAssemblyStateCreateInfo().setTopology(vk::PrimitiveTopology::eTriangleList);

        // TODO: Where are pViewports and pScissors set?
        auto const viewportInfo = vk::PipelineViewportStateCreateInfo().setViewportCount(1).setScissorCount(1);

        auto const rasterizationInfo = vk::PipelineRasterizationStateCreateInfo()
                                           .setDepthClampEnable(VK_FALSE)
                                           .setRasterizerDiscardEnable(VK_FALSE)
                                           .setPolygonMode(vk::PolygonMode::eFill)
                                           .setCullMode(vk::CullModeFlagBits::eBack)
                                           .setFrontFace(vk::FrontFace::eCounterClockwise)
                                           .setDepthBiasEnable(VK_FALSE)
                                           .setLineWidth(1.0f);

        auto const multisampleInfo = vk::PipelineMultisampleStateCreateInfo();

        auto const stencilOp = vk::StencilOpState()
                                   .setFailOp(vk::StencilOp::eKeep)
                                   .setPassOp(vk::StencilOp::eKeep)
                                   .setCompareOp(vk::CompareOp::eAlways);

        auto const depthStencilInfo = vk::PipelineDepthStencilStateCreateInfo()
                                          .setDepthTestEnable(VK_TRUE)
                                          .setDepthWriteEnable(VK_TRUE)
                                          .setDepthCompareOp(vk::CompareOp::eLessOrEqual)
                                          .setDepthBoundsTestEnable(VK_FALSE)
                                          .setStencilTestEnable(VK_FALSE)
                                          .setFront(stencilOp)
                                          .setBack(stencilOp);

        vk::PipelineColorBlendAttachmentState const colorBlendAttachments[1] = {
            vk::PipelineColorBlendAttachmentState().setColorWriteMask(
                vk::ColorComponentFlagBits::eR | vk::ColorComponentFlagBits::eG | vk::ColorComponentFlagBits::eB |
                vk::ColorComponentFlagBits::eA)};

        auto const colorBlendInfo =
            vk::PipelineColorBlendStateCreateInfo().setAttachmentCount(1).setPAttachments(colorBlendAttachments);

        vk::DynamicState const dynamicStates[2] = {vk::DynamicState::eViewport, vk::DynamicState::eScissor};

        auto const dynamicStateInfo = vk::PipelineDynamicStateCreateInfo().setPDynamicStates(dynamicStates).setDynamicStateCount(2);

        auto const pipeline = vk::GraphicsPipelineCreateInfo()
                                  .setStageCount(2)
                                  .setPStages(shaderStageInfo)
                                  .setPVertexInputState(&vertexInputInfo)
                                  .setPInputAssemblyState(&inputAssemblyInfo)
                                  .setPViewportState(&viewportInfo)
                                  .setPRasterizationState(&rasterizationInfo)
                                  .setPMultisampleState(&multisampleInfo)
                                  .setPDepthStencilState(&depthStencilInfo)
                                  .setPColorBlendState(&colorBlendInfo)
                                  .setPDynamicState(&dynamicStateInfo)
                                  .setLayout(pipeline_layout)
                                  .setRenderPass(render_pass);

        result = device.createGraphicsPipelines(pipelineCache, 1, &pipeline, nullptr, &this->pipeline);
        VERIFY(result == vk::Result::eSuccess);

        device.destroyShaderModule(frag_shader_module, nullptr);
        device.destroyShaderModule(vert_shader_module, nullptr);
    }

    void Demo::prepare_render_pass() {
        // The initial layout for the color and depth attachments will be LAYOUT_UNDEFINED
        // because at the start of the renderpass, we don't care about their contents.
        // At the start of the subpass, the color attachment's layout will be transitioned
        // to LAYOUT_COLOR_ATTACHMENT_OPTIMAL and the depth stencil attachment's layout
        // will be transitioned to LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL.  At the end of
        // the renderpass, the color attachment's layout will be transitioned to
        // LAYOUT_PRESENT_SRC_KHR to be ready to present.  This is all done as part of
        // the renderpass, no barriers are necessary.
        const vk::AttachmentDescription attachments[2] = {vk::AttachmentDescription()
                                                              .setFormat(format)
                                                              .setSamples(vk::SampleCountFlagBits::e1)
                                                              .setLoadOp(vk::AttachmentLoadOp::eClear)
                                                              .setStoreOp(vk::AttachmentStoreOp::eStore)
                                                              .setStencilLoadOp(vk::AttachmentLoadOp::eDontCare)
                                                              .setStencilStoreOp(vk::AttachmentStoreOp::eDontCare)
                                                              .setInitialLayout(vk::ImageLayout::eUndefined)
                                                              .setFinalLayout(vk::ImageLayout::ePresentSrcKHR),
                                                          vk::AttachmentDescription()
                                                              .setFormat(depth.format)
                                                              .setSamples(vk::SampleCountFlagBits::e1)
                                                              .setLoadOp(vk::AttachmentLoadOp::eClear)
                                                              .setStoreOp(vk::AttachmentStoreOp::eDontCare)
                                                              .setStencilLoadOp(vk::AttachmentLoadOp::eDontCare)
                                                              .setStencilStoreOp(vk::AttachmentStoreOp::eDontCare)
                                                              .setInitialLayout(vk::ImageLayout::eUndefined)
                                                              .setFinalLayout(vk::ImageLayout::eDepthStencilAttachmentOptimal)};

        auto const color_reference = vk::AttachmentReference().setAttachment(0).setLayout(vk::ImageLayout::eColorAttachmentOptimal);

        auto const depth_reference =
            vk::AttachmentReference().setAttachment(1).setLayout(vk::ImageLayout::eDepthStencilAttachmentOptimal);

        auto const subpass = vk::SubpassDescription()
                                 .setPipelineBindPoint(vk::PipelineBindPoint::eGraphics)
                                 .setInputAttachmentCount(0)
                                 .setPInputAttachments(nullptr)
                                 .setColorAttachmentCount(1)
                                 .setPColorAttachments(&color_reference)
                                 .setPResolveAttachments(nullptr)
                                 .setPDepthStencilAttachment(&depth_reference)
                                 .setPreserveAttachmentCount(0)
                                 .setPPreserveAttachments(nullptr);

        auto const rp_info = vk::RenderPassCreateInfo()
                                 .setAttachmentCount(2)
                                 .setPAttachments(attachments)
                                 .setSubpassCount(1)
                                 .setPSubpasses(&subpass)
                                 .setDependencyCount(0)
                                 .setPDependencies(nullptr);

        auto result = device.createRenderPass(&rp_info, nullptr, &render_pass);
        VERIFY(result == vk::Result::eSuccess);
    }

    vk::ShaderModule Demo::prepare_shader_module(const void *code, size_t size) {
        auto const moduleCreateInfo = vk::ShaderModuleCreateInfo().setCodeSize(size).setPCode((uint32_t const *)code);

        vk::ShaderModule module;
        auto result = device.createShaderModule(&moduleCreateInfo, nullptr, &module);
        VERIFY(result == vk::Result::eSuccess);

        return module;
    }

    void Demo::prepare_texture_image(const char *filename, texture_object *tex_obj, vk::ImageTiling tiling,
                                     vk::ImageUsageFlags usage, vk::MemoryPropertyFlags required_props) {
        int32_t tex_width;
        int32_t tex_height;
        if (!loadTexture(filename, nullptr, nullptr, &tex_width, &tex_height)) {
            ERR_EXIT("Failed to load textures", "Load Texture Failure");
        }

        tex_obj->tex_width = tex_width;
        tex_obj->tex_height = tex_height;

        auto const image_create_info = vk::ImageCreateInfo()
                                           .setImageType(vk::ImageType::e2D)
                                           .setFormat(vk::Format::eR8G8B8A8Unorm)
                                           .setExtent({(uint32_t)tex_width, (uint32_t)tex_height, 1})
                                           .setMipLevels(1)
                                           .setArrayLayers(1)
                                           .setSamples(vk::SampleCountFlagBits::e1)
                                           .setTiling(tiling)
                                           .setUsage(usage)
                                           .setSharingMode(vk::SharingMode::eExclusive)
                                           .setQueueFamilyIndexCount(0)
                                           .setPQueueFamilyIndices(nullptr)
                                           .setInitialLayout(vk::ImageLayout::ePreinitialized);

        auto result = device.createImage(&image_create_info, nullptr, &tex_obj->image);
        VERIFY(result == vk::Result::eSuccess);

        vk::MemoryRequirements mem_reqs;
        device.getImageMemoryRequirements(tex_obj->image, &mem_reqs);

        tex_obj->mem_alloc.setAllocationSize(mem_reqs.size);
        tex_obj->mem_alloc.setMemoryTypeIndex(0);

        auto pass = memory_type_from_properties(mem_reqs.memoryTypeBits, required_props, &tex_obj->mem_alloc.memoryTypeIndex);
        VERIFY(pass == true);

        result = device.allocateMemory(&tex_obj->mem_alloc, nullptr, &(tex_obj->mem));
        VERIFY(result == vk::Result::eSuccess);

        result = device.bindImageMemory(tex_obj->image, tex_obj->mem, 0);
        VERIFY(result == vk::Result::eSuccess);

        if (required_props & vk::MemoryPropertyFlagBits::eHostVisible) {
            auto const subres =
                vk::ImageSubresource().setAspectMask(vk::ImageAspectFlagBits::eColor).setMipLevel(0).setArrayLayer(0);
            vk::SubresourceLayout layout;
            device.getImageSubresourceLayout(tex_obj->image, &subres, &layout);

            auto data = device.mapMemory(tex_obj->mem, 0, tex_obj->mem_alloc.allocationSize);
            VERIFY(data.result == vk::Result::eSuccess);

            if (!loadTexture(filename, (uint8_t *)data.value, &layout, &tex_width, &tex_height)) {
                fprintf(stderr, "Error loading texture: %s\n", filename);
            }

            device.unmapMemory(tex_obj->mem);
        }

        tex_obj->imageLayout = vk::ImageLayout::eShaderReadOnlyOptimal;
    }

    void Demo::prepare_textures() {
        vk::Format const tex_format = vk::Format::eR8G8B8A8Unorm;
        vk::FormatProperties props;
        gpu.getFormatProperties(tex_format, &props);

        for (uint32_t i = 0; i < texture_count; i++) {
            if ((props.linearTilingFeatures & vk::FormatFeatureFlagBits::eSampledImage) && !use_staging_buffer) {
                /* Device can texture using linear textures */
                prepare_texture_image(tex_files[i], &textures[i], vk::ImageTiling::eLinear, vk::ImageUsageFlagBits::eSampled,
                                      vk::MemoryPropertyFlagBits::eHostVisible | vk::MemoryPropertyFlagBits::eHostCoherent);
                // Nothing in the pipeline needs to be complete to start, and don't allow fragment
                // shader to run until layout transition completes
                set_image_layout(textures[i].image, vk::ImageAspectFlagBits::eColor, vk::ImageLayout::ePreinitialized,
                                 textures[i].imageLayout, vk::AccessFlagBits::eHostWrite, vk::PipelineStageFlagBits::eTopOfPipe,
                                 vk::PipelineStageFlagBits::eFragmentShader);
                staging_texture.image = vk::Image();
            } else if (props.optimalTilingFeatures & vk::FormatFeatureFlagBits::eSampledImage) {
                /* Must use staging buffer to copy linear texture to optimized */

                prepare_texture_image(tex_files[i], &staging_texture, vk::ImageTiling::eLinear,
                                      vk::ImageUsageFlagBits::eTransferSrc,
                                      vk::MemoryPropertyFlagBits::eHostVisible | vk::MemoryPropertyFlagBits::eHostCoherent);

                prepare_texture_image(tex_files[i], &textures[i], vk::ImageTiling::eOptimal,
                                      vk::ImageUsageFlagBits::eTransferDst | vk::ImageUsageFlagBits::eSampled,
                                      vk::MemoryPropertyFlagBits::eDeviceLocal);

                set_image_layout(staging_texture.image, vk::ImageAspectFlagBits::eColor, vk::ImageLayout::ePreinitialized,
                                 vk::ImageLayout::eTransferSrcOptimal, vk::AccessFlagBits::eHostWrite,
                                 vk::PipelineStageFlagBits::eTopOfPipe, vk::PipelineStageFlagBits::eTransfer);

                set_image_layout(textures[i].image, vk::ImageAspectFlagBits::eColor, vk::ImageLayout::ePreinitialized,
                                 vk::ImageLayout::eTransferDstOptimal, vk::AccessFlagBits::eHostWrite,
                                 vk::PipelineStageFlagBits::eTopOfPipe, vk::PipelineStageFlagBits::eTransfer);

                auto const subresource = vk::ImageSubresourceLayers()
                                             .setAspectMask(vk::ImageAspectFlagBits::eColor)
                                             .setMipLevel(0)
                                             .setBaseArrayLayer(0)
                                             .setLayerCount(1);

                auto const copy_region =
                    vk::ImageCopy()
                        .setSrcSubresource(subresource)
                        .setSrcOffset({0, 0, 0})
                        .setDstSubresource(subresource)
                        .setDstOffset({0, 0, 0})
                        .setExtent({(uint32_t)staging_texture.tex_width, (uint32_t)staging_texture.tex_height, 1});

                cmd.copyImage(staging_texture.image, vk::ImageLayout::eTransferSrcOptimal, textures[i].image,
                              vk::ImageLayout::eTransferDstOptimal, 1, &copy_region);

                set_image_layout(textures[i].image, vk::ImageAspectFlagBits::eColor, vk::ImageLayout::eTransferDstOptimal,
                                 textures[i].imageLayout, vk::AccessFlagBits::eTransferWrite, vk::PipelineStageFlagBits::eTransfer,
                                 vk::PipelineStageFlagBits::eFragmentShader);
            } else {
                assert(!"No support for R8G8B8A8_UNORM as texture image format");
            }

            auto const samplerInfo = vk::SamplerCreateInfo()
                                         .setMagFilter(vk::Filter::eNearest)
                                         .setMinFilter(vk::Filter::eNearest)
                                         .setMipmapMode(vk::SamplerMipmapMode::eNearest)
                                         .setAddressModeU(vk::SamplerAddressMode::eClampToEdge)
                                         .setAddressModeV(vk::SamplerAddressMode::eClampToEdge)
                                         .setAddressModeW(vk::SamplerAddressMode::eClampToEdge)
                                         .setMipLodBias(0.0f)
                                         .setAnisotropyEnable(VK_FALSE)
                                         .setMaxAnisotropy(1)
                                         .setCompareEnable(VK_FALSE)
                                         .setCompareOp(vk::CompareOp::eNever)
                                         .setMinLod(0.0f)
                                         .setMaxLod(0.0f)
                                         .setBorderColor(vk::BorderColor::eFloatOpaqueWhite)
                                         .setUnnormalizedCoordinates(VK_FALSE);

            auto result = device.createSampler(&samplerInfo, nullptr, &textures[i].sampler);
            VERIFY(result == vk::Result::eSuccess);

            auto const viewInfo = vk::ImageViewCreateInfo()
                                      .setImage(textures[i].image)
                                      .setViewType(vk::ImageViewType::e2D)
                                      .setFormat(tex_format)
                                      .setSubresourceRange(vk::ImageSubresourceRange(vk::ImageAspectFlagBits::eColor, 0, 1, 0, 1));

            result = device.createImageView(&viewInfo, nullptr, &textures[i].view);
            VERIFY(result == vk::Result::eSuccess);
        }
    }

    vk::ShaderModule Demo::prepare_vs() {
        size_t size = 0;
        void *vertShaderCode = read_spv("cube-vert.spv", &size);
        if (!vertShaderCode) {
            ERR_EXIT("Failed to load cube-vert.spv", "Load Shader Failure");
        }

        vert_shader_module = prepare_shader_module(vertShaderCode, size);

        free(vertShaderCode);

        return vert_shader_module;
    }

    char *Demo::read_spv(const char *filename, size_t *psize) {
        FILE *fp = fopen(filename, "rb");
        if (!fp) {
            return nullptr;
        }

        fseek(fp, 0L, SEEK_END);
        long int size = ftell(fp);

        fseek(fp, 0L, SEEK_SET);

        void *shader_code = malloc(size);
        size_t retval = fread(shader_code, size, 1, fp);
        VERIFY(retval == 1);

        *psize = size;

        fclose(fp);

        return (char *)shader_code;
    }

    void Demo::resize() {
        uint32_t i;

        // Don't react to resize until after first initialization.
        if (!prepared) {
            return;
        }

        // In order to properly resize the window, we must re-create the
        // swapchain
        // AND redo the command buffers, etc.
        //
        // First, perform part of the cleanup() function:
        prepared = false;
        auto result = device.waitIdle();
        VERIFY(result == vk::Result::eSuccess);

        for (i = 0; i < swapchainImageCount; i++) {
            device.destroyFramebuffer(swapchain_image_resources[i].framebuffer, nullptr);
        }

        device.destroyDescriptorPool(desc_pool, nullptr);

        device.destroyPipeline(pipeline, nullptr);
        device.destroyPipelineCache(pipelineCache, nullptr);
        device.destroyRenderPass(render_pass, nullptr);
        device.destroyPipelineLayout(pipeline_layout, nullptr);
        device.destroyDescriptorSetLayout(desc_layout, nullptr);

        for (i = 0; i < texture_count; i++) {
            device.destroyImageView(textures[i].view, nullptr);
            device.destroyImage(textures[i].image, nullptr);
            device.freeMemory(textures[i].mem, nullptr);
            device.destroySampler(textures[i].sampler, nullptr);
        }

        device.destroyImageView(depth.view, nullptr);
        device.destroyImage(depth.image, nullptr);
        device.freeMemory(depth.mem, nullptr);

        for (i = 0; i < swapchainImageCount; i++) {
            device.destroyImageView(swapchain_image_resources[i].view, nullptr);
            device.freeCommandBuffers(cmd_pool, 1, &swapchain_image_resources[i].cmd);
            device.destroyBuffer(swapchain_image_resources[i].uniform_buffer, nullptr);
            device.freeMemory(swapchain_image_resources[i].uniform_memory, nullptr);
        }

        device.destroyCommandPool(cmd_pool, nullptr);
        if (separate_present_queue) {
            device.destroyCommandPool(present_cmd_pool, nullptr);
        }

        // Second, re-perform the prepare() function, which will re-create the
        // swapchain.
        prepare();
    }

    void Demo::set_image_layout(vk::Image image, vk::ImageAspectFlags aspectMask, vk::ImageLayout oldLayout,
                                vk::ImageLayout newLayout, vk::AccessFlags srcAccessMask, vk::PipelineStageFlags src_stages,
                                vk::PipelineStageFlags dest_stages) {
        assert(cmd);

        auto DstAccessMask = [](vk::ImageLayout const &layout) {
            vk::AccessFlags flags;

            switch (layout) {
                case vk::ImageLayout::eTransferDstOptimal:
                    // Make sure anything that was copying from this image has
                    // completed
                    flags = vk::AccessFlagBits::eTransferWrite;
                    break;
                case vk::ImageLayout::eColorAttachmentOptimal:
                    flags = vk::AccessFlagBits::eColorAttachmentWrite;
                    break;
                case vk::ImageLayout::eDepthStencilAttachmentOptimal:
                    flags = vk::AccessFlagBits::eDepthStencilAttachmentWrite;
                    break;
                case vk::ImageLayout::eShaderReadOnlyOptimal:
                    // Make sure any Copy or CPU writes to image are flushed
                    flags = vk::AccessFlagBits::eShaderRead | vk::AccessFlagBits::eInputAttachmentRead;
                    break;
                case vk::ImageLayout::eTransferSrcOptimal:
                    flags = vk::AccessFlagBits::eTransferRead;
                    break;
                case vk::ImageLayout::ePresentSrcKHR:
                    flags = vk::AccessFlagBits::eMemoryRead;
                    break;
                default:
                    break;
            }

            return flags;
        };

        auto const barrier = vk::ImageMemoryBarrier()
                                 .setSrcAccessMask(srcAccessMask)
                                 .setDstAccessMask(DstAccessMask(newLayout))
                                 .setOldLayout(oldLayout)
                                 .setNewLayout(newLayout)
                                 .setSrcQueueFamilyIndex(0)
                                 .setDstQueueFamilyIndex(0)
                                 .setImage(image)
                                 .setSubresourceRange(vk::ImageSubresourceRange(aspectMask, 0, 1, 0, 1));

        cmd.pipelineBarrier(src_stages, dest_stages, vk::DependencyFlagBits(), 0, nullptr, 0, nullptr, 1, &barrier);
    }

    void Demo::update_data_buffer() {
        mat4x4 VP;
        mat4x4_mul(VP, projection_matrix, view_matrix);

        // Rotate around the Y axis
        mat4x4 Model;
        mat4x4_dup(Model, model_matrix);
        mat4x4_rotate(model_matrix, Model, 0.0f, 1.0f, 0.0f, (float)degreesToRadians(spin_angle));

        mat4x4 MVP;
        mat4x4_mul(MVP, VP, model_matrix);

        auto data = device.mapMemory(swapchain_image_resources[current_buffer].uniform_memory, 0, VK_WHOLE_SIZE, vk::MemoryMapFlags());
        VERIFY(data.result == vk::Result::eSuccess);

        memcpy(data.value, (const void *)&MVP[0][0], sizeof(MVP));

        device.unmapMemory(swapchain_image_resources[current_buffer].uniform_memory);
    }

    bool Demo::loadTexture(const char *filename, uint8_t *rgba_data, vk::SubresourceLayout *layout, int32_t *width,
                           int32_t *height) {
        FILE *fPtr = fopen(filename, "rb");
        if (!fPtr) {
            return false;
        }

        char header[256];
        char *cPtr = fgets(header, 256, fPtr);  // P6
        if (cPtr == nullptr || strncmp(header, "P6\n", 3)) {
            fclose(fPtr);
            return false;
        }

        do {
            cPtr = fgets(header, 256, fPtr);
            if (cPtr == nullptr) {
                fclose(fPtr);
                return false;
            }
        } while (!strncmp(header, "#", 1));

        sscanf(header, "%u %u", width, height);
        if (rgba_data == nullptr) {
            fclose(fPtr);
            return true;
        }

        char *result = fgets(header, 256, fPtr);  // Format
        VERIFY(result != nullptr);
        if (cPtr == nullptr || strncmp(header, "255\n", 3)) {
            fclose(fPtr);
            return false;
        }

        for (int y = 0; y < *height; y++) {
            uint8_t *rowPtr = rgba_data;

            for (int x = 0; x < *width; x++) {
                size_t s = fread(rowPtr, 3, 1, fPtr);
                (void)s;
                rowPtr[3] = 255; /* Alpha of 1 */
                rowPtr += 4;
            }

            rgba_data += layout->rowPitch;
        }

        fclose(fPtr);
        return true;
    }

    bool Demo::memory_type_from_properties(uint32_t typeBits, vk::MemoryPropertyFlags requirements_mask, uint32_t *typeIndex) {
        // Search memtypes to find first index with those properties
        for (uint32_t i = 0; i < VK_MAX_MEMORY_TYPES; i++) {
            if ((typeBits & 1) == 1) {
                // Type is available, does it match user properties?
                if ((memory_properties.memoryTypes[i].propertyFlags & requirements_mask) == requirements_mask) {
                    *typeIndex = i;
                    return true;
                }
            }
            typeBits >>= 1;
        }

        // No memory types matched, return failure
        return false;
    }

#if defined(VK_USE_PLATFORM_WIN32_KHR)
    void Demo::run() {
        if (!prepared) {
            return;
        }

        draw();
        curFrame++;

        if (frameCount != INT_MAX && curFrame == frameCount) {
            PostQuitMessage(validation_error);
        }
    }

    void Demo::create_window() {
        WNDCLASSEX win_class;

        // Initialize the window class structure:
        win_class.cbSize = sizeof(WNDCLASSEX);
        win_class.style = CS_HREDRAW | CS_VREDRAW;
        win_class.lpfnWndProc = WndProc;
        win_class.cbClsExtra = 0;
        win_class.cbWndExtra = 0;
        win_class.hInstance = connection;  // hInstance
        win_class.hIcon = LoadIcon(nullptr, IDI_APPLICATION);
        win_class.hCursor = LoadCursor(nullptr, IDC_ARROW);
        win_class.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
        win_class.lpszMenuName = nullptr;
        win_class.lpszClassName = name;
        win_class.hIconSm = LoadIcon(nullptr, IDI_WINLOGO);

        // Register window class:
        if (!RegisterClassEx(&win_class)) {
            // It didn't work, so try to give a useful error:
            printf("Unexpected error trying to start the application!\n");
            fflush(stdout);
            exit(1);
        }

        // Create window with the registered class:
        RECT wr = {0, 0, static_cast<LONG>(width), static_cast<LONG>(height)};
        AdjustWindowRect(&wr, WS_OVERLAPPEDWINDOW, FALSE);
        window = CreateWindowEx(0,
                                name,                  // class name
                                name,                  // app name
                                WS_OVERLAPPEDWINDOW |  // window style
                                    WS_VISIBLE | WS_SYSMENU,
                                100, 100,            // x/y coords
                                wr.right - wr.left,  // width
                                wr.bottom - wr.top,  // height
                                nullptr,             // handle to parent
                                nullptr,             // handle to menu
                                connection,          // hInstance
                                nullptr);            // no extra parameters

        if (!window) {
            // It didn't work, so try to give a useful error:
            printf("Cannot create a window in which to draw!\n");
            fflush(stdout);
            exit(1);
        }

        // Window client area size must be at least 1 pixel high, to prevent
        // crash.
        minsize.x = GetSystemMetrics(SM_CXMINTRACK);
        minsize.y = GetSystemMetrics(SM_CYMINTRACK) + 1;
    }
#elif defined(VK_USE_PLATFORM_XLIB_KHR)

    void Demo::create_xlib_window() {
        XInitThreads();
        display = XOpenDisplay(nullptr);
        long visualMask = VisualScreenMask;
        int numberOfVisuals;
        XVisualInfo vInfoTemplate = {};
        vInfoTemplate.screen = DefaultScreen(display);
        XVisualInfo *visualInfo = XGetVisualInfo(display, visualMask, &vInfoTemplate, &numberOfVisuals);

        Colormap colormap = XCreateColormap(display, RootWindow(display, vInfoTemplate.screen), visualInfo->visual, AllocNone);

        XSetWindowAttributes windowAttributes = {};
        windowAttributes.colormap = colormap;
        windowAttributes.background_pixel = 0xFFFFFFFF;
        windowAttributes.border_pixel = 0;
        windowAttributes.event_mask = KeyPressMask | KeyReleaseMask | StructureNotifyMask | ExposureMask;

        xlib_window = XCreateWindow(display, RootWindow(display, vInfoTemplate.screen), 0, 0, width, height, 0, visualInfo->depth,
                                    InputOutput, visualInfo->visual, CWBackPixel | CWBorderPixel | CWEventMask | CWColormap,
                                    &windowAttributes);

        XSelectInput(display, xlib_window, ExposureMask | KeyPressMask);
        XMapWindow(display, xlib_window);
        XFlush(display);
        xlib_wm_delete_window = XInternAtom(display, "WM_DELETE_WINDOW", False);
    }

    void Demo::handle_xlib_event(const XEvent *event) {
        switch (event->type) {
            case ClientMessage:
                if ((Atom)event->xclient.data.l[0] == xlib_wm_delete_window) {
                    quit = true;
                }
                break;
            case KeyPress:
                switch (event->xkey.keycode) {
                    case 0x9:  // Escape
                        quit = true;
                        break;
                    case 0x71:  // left arrow key
                        spin_angle -= spin_increment;
                        break;
                    case 0x72:  // right arrow key
                        spin_angle += spin_increment;
                        break;
                    case 0x41:  // space bar
                        pause = !pause;
                        break;
                }
                break;
            case ConfigureNotify:
                if (((int32_t)width != event->xconfigure.width) || ((int32_t)height != event->xconfigure.height)) {
                    width = event->xconfigure.width;
                    height = event->xconfigure.height;
                    resize();
                }
                break;
            default:
                break;
        }
    }

    void Demo::run_xlib() {
        while (!quit) {
            XEvent event;

            if (pause) {
                XNextEvent(display, &event);
                handle_xlib_event(&event);
            }
            while (XPending(display) > 0) {
                XNextEvent(display, &event);
                handle_xlib_event(&event);
            }

            draw();
            curFrame++;

            if (frameCount != UINT32_MAX && curFrame == frameCount) {
                quit = true;
            }
        }
    }
#elif defined(VK_USE_PLATFORM_XCB_KHR)

    void Demo::handle_xcb_event(const xcb_generic_event_t *event) {
        uint8_t event_code = event->response_type & 0x7f;
        switch (event_code) {
            case XCB_EXPOSE:
                // TODO: Resize window
                break;
            case XCB_CLIENT_MESSAGE:
                if ((*(xcb_client_message_event_t *)event).data.data32[0] == (*atom_wm_delete_window).atom) {
                    quit = true;
                }
                break;
            case XCB_KEY_RELEASE: {
                const xcb_key_release_event_t *key = (const xcb_key_release_event_t *)event;

                switch (key->detail) {
                    case 0x9:  // Escape
                        quit = true;
                        break;
                    case 0x71:  // left arrow key
                        spin_angle -= spin_increment;
                        break;
                    case 0x72:  // right arrow key
                        spin_angle += spin_increment;
                        break;
                    case 0x41:  // space bar
                        pause = !pause;
                        break;
                }
            } break;
            case XCB_CONFIGURE_NOTIFY: {
                const xcb_configure_notify_event_t *cfg = (const xcb_configure_notify_event_t *)event;
                if ((width != cfg->width) || (height != cfg->height)) {
                    width = cfg->width;
                    height = cfg->height;
                    resize();
                }
            } break;
            default:
                break;
        }
    }

    void Demo::run_xcb() {
        xcb_flush(connection);

        while (!quit) {
            xcb_generic_event_t *event;

            if (pause) {
                event = xcb_wait_for_event(connection);
            } else {
                event = xcb_poll_for_event(connection);
            }
            while (event) {
                handle_xcb_event(event);
                free(event);
                event = xcb_poll_for_event(connection);
            }

            draw();
            curFrame++;
            if (frameCount != UINT32_MAX && curFrame == frameCount) {
                quit = true;
            }
        }
    }

    void Demo::create_xcb_window() {
        uint32_t value_mask, value_list[32];

        xcb_window = xcb_generate_id(connection);

        value_mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
        value_list[0] = screen->black_pixel;
        value_list[1] = XCB_EVENT_MASK_KEY_RELEASE | XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_STRUCTURE_NOTIFY;

        xcb_create_window(connection, XCB_COPY_FROM_PARENT, xcb_window, screen->root, 0, 0, width, height, 0,
                          XCB_WINDOW_CLASS_INPUT_OUTPUT, screen->root_visual, value_mask, value_list);

        /* Magic code that will send notification when window is destroyed */
        xcb_intern_atom_cookie_t cookie = xcb_intern_atom(connection, 1, 12, "WM_PROTOCOLS");
        xcb_intern_atom_reply_t *reply = xcb_intern_atom_reply(connection, cookie, 0);

        xcb_intern_atom_cookie_t cookie2 = xcb_intern_atom(connection, 0, 16, "WM_DELETE_WINDOW");
        atom_wm_delete_window = xcb_intern_atom_reply(connection, cookie2, 0);

        xcb_change_property(connection, XCB_PROP_MODE_REPLACE, xcb_window, (*reply).atom, 4, 32, 1, &(*atom_wm_delete_window).atom);

        free(reply);

        xcb_map_window(connection, xcb_window);

        // Force the x/y coordinates to 100,100 results are identical in
        // consecutive
        // runs
        const uint32_t coords[] = {100, 100};
        xcb_configure_window(connection, xcb_window, XCB_CONFIG_WINDOW_X | XCB_CONFIG_WINDOW_Y, coords);
    }
#elif defined(VK_USE_PLATFORM_WAYLAND_KHR)

    void Demo::run() {
        while (!quit) {
            if (pause) {
                wl_display_dispatch(display);
            } else {
                wl_display_dispatch_pending(display);
                update_data_buffer();
                draw();
                curFrame++;
                if (frameCount != UINT32_MAX && curFrame == frameCount) {
                    quit = true;
                }
            }
        }
    }

    void Demo::create_window() {
        window = wl_compositor_create_surface(compositor);
        if (!window) {
            printf("Can not create wayland_surface from compositor!\n");
            fflush(stdout);
            exit(1);
        }

        shell_surface = wl_shell_get_shell_surface(shell, window);
        if (!shell_surface) {
            printf("Can not get shell_surface from wayland_surface!\n");
            fflush(stdout);
            exit(1);
        }

        wl_shell_surface_add_listener(shell_surface, &shell_surface_listener, this);
        wl_shell_surface_set_toplevel(shell_surface);
        wl_shell_surface_set_title(shell_surface, APP_SHORT_NAME);
    }
#elif defined(VK_USE_PLATFORM_MIR_KHR)
#elif defined(VK_USE_PLATFORM_DISPLAY_KHR)

    vk::Result Demo::create_display_surface() {
        vk::Result result;
        uint32_t display_count;
        uint32_t mode_count;
        uint32_t plane_count;
        vk::DisplayPropertiesKHR display_props;
        vk::DisplayKHR display;
        vk::DisplayModePropertiesKHR mode_props;
        vk::DisplayPlanePropertiesKHR *plane_props;
        vk::Bool32 found_plane = VK_FALSE;
        uint32_t plane_index;
        vk::Extent2D image_extent;

        // Get the first display
        result = gpu.getDisplayPropertiesKHR(&display_count, nullptr);
        VERIFY(result == vk::Result::eSuccess);

        if (display_count == 0) {
            printf("Cannot find any display!\n");
            fflush(stdout);
            exit(1);
        }

        display_count = 1;
        result = gpu.getDisplayPropertiesKHR(&display_count, &display_props);
        VERIFY((result == vk::Result::eSuccess) || (result == vk::Result::eIncomplete));

        display = display_props.display;

        // Get the first mode of the display
        result = gpu.getDisplayModePropertiesKHR(display, &mode_count, nullptr);
        VERIFY(result == vk::Result::eSuccess);

        if (mode_count == 0) {
            printf("Cannot find any mode for the display!\n");
            fflush(stdout);
            exit(1);
        }

        mode_count = 1;
        result = gpu.getDisplayModePropertiesKHR(display, &mode_count, &mode_props);
        VERIFY((result == vk::Result::eSuccess) || (result == vk::Result::eIncomplete));

        // Get the list of planes
        result = gpu.getDisplayPlanePropertiesKHR(&plane_count, nullptr);
        VERIFY(result == vk::Result::eSuccess);

        if (plane_count == 0) {
            printf("Cannot find any plane!\n");
            fflush(stdout);
            exit(1);
        }

        plane_props = (vk::DisplayPlanePropertiesKHR *)malloc(sizeof(vk::DisplayPlanePropertiesKHR) * plane_count);
        VERIFY(plane_props != nullptr);

        result = gpu.getDisplayPlanePropertiesKHR(&plane_count, plane_props);
        VERIFY(result == vk::Result::eSuccess);

        // Find a plane compatible with the display
        for (plane_index = 0; plane_index < plane_count; plane_index++) {
            uint32_t supported_count;
            vk::DisplayKHR *supported_displays;

            // Disqualify planes that are bound to a different display
            if (plane_props[plane_index].currentDisplay && (plane_props[plane_index].currentDisplay != display)) {
                continue;
            }

            result = gpu.getDisplayPlaneSupportedDisplaysKHR(plane_index, &supported_count, nullptr);
            VERIFY(result == vk::Result::eSuccess);

            if (supported_count == 0) {
                continue;
            }

            supported_displays = (vk::DisplayKHR *)malloc(sizeof(vk::DisplayKHR) * supported_count);
            VERIFY(supported_displays != nullptr);

            result = gpu.getDisplayPlaneSupportedDisplaysKHR(plane_index, &supported_count, supported_displays);
            VERIFY(result == vk::Result::eSuccess);

            for (uint32_t i = 0; i < supported_count; i++) {
                if (supported_displays[i] == display) {
                    found_plane = VK_TRUE;
                    break;
                }
            }

            free(supported_displays);

            if (found_plane) {
                break;
            }
        }

        if (!found_plane) {
            printf("Cannot find a plane compatible with the display!\n");
            fflush(stdout);
            exit(1);
        }

        free(plane_props);

        vk::DisplayPlaneCapabilitiesKHR planeCaps;
        vk::getDisplayPlaneCapabilitiesKHR(gpu, mode_props.displayMode, plane_index, &planeCaps);
        // Find a supported alpha mode
        vk::CompositeAlphaFlagBitsKHR alphaMode = vk::CompositeAlphaFlagBitsKHR::eOpaque;
        vk::CompositeAlphaFlagBitsKHR alphaModes[4] = {
            vk::CompositeAlphaFlagBitsKHR::eOpaque,
            vk::CompositeAlphaFlagBitsKHR::eGlobal,
            vk::CompositeAlphaFlagBitsKHR::ePerPixel,
            vk::CompositeAlphaFlagBitsKHR::ePerPixelPremultiplied,
        };
        for (uint32_t i = 0; i < sizeof(alphaModes); i++) {
            if (planeCaps.supportedAlpha & alphaModes[i]) {
                alphaMode = alphaModes[i];
                break;
            }
        }

        image_extent.setWidth(mode_props.parameters.visibleRegion.width);
        image_extent.setHeight(mode_props.parameters.visibleRegion.height);

        auto const createInfo = vk::DisplaySurfaceCreateInfoKHR()
                                    .setDisplayMode(mode_props.displayMode)
                                    .setPlaneIndex(plane_index)
                                    .setPlaneStackIndex(plane_props[plane_index].currentStackIndex)
                                    .setGlobalAlpha(1.0f)
                                    .setAlphaMode(alphaMode)
                                    .setImageExtent(image_extent);

        return inst.createDisplayPlaneSurfaceKHR(&createInfo, nullptr, &surface);
    }

    void Demo::run_display() {
        while (!quit) {
            draw();
            curFrame++;

            if (frameCount != INT32_MAX && curFrame == frameCount) {
                quit = true;
            }
        }
    }
#endif

#if _WIN32
// Include header required for parsing the command line options.
#include <shellapi.h>

Demo demo;

// MS-Windows event handling function:
LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
    switch (uMsg) {
        case WM_CLOSE:
            PostQuitMessage(validation_error);
            break;
        case WM_PAINT:
            demo.run();
            break;
        case WM_GETMINMAXINFO:  // set window's minimum size
            ((MINMAXINFO *)lParam)->ptMinTrackSize = demo.minsize;
            return 0;
        case WM_SIZE:
            // Resize the application to the new window size, except when
            // it was minimized. Vulkan doesn't support images or swapchains
            // with width=0 and height=0.
            if (wParam != SIZE_MINIMIZED) {
                demo.width = lParam & 0xffff;
                demo.height = (lParam & 0xffff0000) >> 16;
                demo.resize();
            }
            break;
        default:
            break;
    }

    return (DefWindowProc(hWnd, uMsg, wParam, lParam));
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR pCmdLine, int nCmdShow) {
    // TODO: Gah.. refactor. This isn't 1989.
    MSG msg;    // message
    bool done;  // flag saying when app is complete
    int argc;
    char **argv;

    // Ensure wParam is initialized.
    msg.wParam = 0;

    // Use the CommandLine functions to get the command line arguments.
    // Unfortunately, Microsoft outputs
    // this information as wide characters for Unicode, and we simply want the
    // Ascii version to be compatible
    // with the non-Windows side.  So, we have to convert the information to
    // Ascii character strings.
    LPWSTR *commandLineArgs = CommandLineToArgvW(GetCommandLineW(), &argc);
    if (nullptr == commandLineArgs) {
        argc = 0;
    }

    if (argc > 0) {
        argv = (char **)malloc(sizeof(char *) * argc);
        if (argv == nullptr) {
            argc = 0;
        } else {
            for (int iii = 0; iii < argc; iii++) {
                size_t wideCharLen = wcslen(commandLineArgs[iii]);
                size_t numConverted = 0;

                argv[iii] = (char *)malloc(sizeof(char) * (wideCharLen + 1));
                if (argv[iii] != nullptr) {
                    wcstombs_s(&numConverted, argv[iii], wideCharLen + 1, commandLineArgs[iii], wideCharLen + 1);
                }
            }
        }
    } else {
        argv = nullptr;
    }

    demo.init(argc, argv);

    // Free up the items we had to allocate for the command line arguments.
    if (argc > 0 && argv != nullptr) {
        for (int iii = 0; iii < argc; iii++) {
            if (argv[iii] != nullptr) {
                free(argv[iii]);
            }
        }
        free(argv);
    }

    demo.connection = hInstance;
    strncpy(demo.name, "cube", APP_NAME_STR_LEN);
    demo.create_window();
    demo.init_vk_swapchain();

    demo.prepare();

    done = false;  // initialize loop condition variable

    // main message loop
    while (!done) {
        PeekMessage(&msg, nullptr, 0, 0, PM_REMOVE);
        if (msg.message == WM_QUIT)  // check for a quit message
        {
            done = true;  // if found, quit app
        } else {
            /* Translate and dispatch to event queue*/
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
        RedrawWindow(demo.window, nullptr, nullptr, RDW_INTERNALPAINT);
    }

    demo.cleanup();

    return (int)msg.wParam;
}

#elif __linux__

int main(int argc, char **argv) {
    Demo demo;

    demo.init(argc, argv);

#if defined(VK_USE_PLATFORM_XCB_KHR)
    demo.create_xcb_window();
#elif defined(VK_USE_PLATFORM_XLIB_KHR)
    demo.use_xlib = true;
    demo.create_xlib_window();
#elif defined(VK_USE_PLATFORM_WAYLAND_KHR)
    demo.create_window();
#elif defined(VK_USE_PLATFORM_MIR_KHR)
#endif

    demo.init_vk_swapchain();

    demo.prepare();

#if defined(VK_USE_PLATFORM_XCB_KHR)
    demo.run_xcb();
#elif defined(VK_USE_PLATFORM_XLIB_KHR)
    demo.run_xlib();
#elif defined(VK_USE_PLATFORM_WAYLAND_KHR)
    demo.run();
#elif defined(VK_USE_PLATFORM_MIR_KHR)
#elif defined(VK_USE_PLATFORM_DISPLAY_KHR)
    demo.run_display();
#endif

    demo.cleanup();

    return validation_error;
}

#else
#error "Platform not supported"
#endif