// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "lib/escher/impl/model_lighting_pass.h"

#include "lib/escher/impl/model_data.h"

namespace escher {
namespace impl {

static const char kVertexShaderMainSourceCode[] = R"GLSL(
layout(location = 0) out vec2 fragUV;

void main() {
  vec4 pos = ComputeVertexPosition();
  gl_Position = vp_matrix * model_transform  * pos;
  fragUV = inUV;
}
)GLSL";

static const char kFragmentShaderSourceCode[] = R"GLSL(
#version 450
#extension GL_ARB_separate_shader_objects : enable

layout(location = 0) in vec2 inUV;

layout(set = 0, binding = 0) uniform PerModel {
  vec2 frag_coord_to_uv_multiplier;
  float time;
  vec3 ambient_light_intensity;
  vec3 direct_light_intensity;
  vec2 shadow_map_uv_multiplier;
};

layout(set = 0, binding = 1) uniform sampler2D light_tex;

layout(set = 1, binding = 0) uniform PerObject {
  mat4 model_transform;
  mat4 light_transform;
  vec4 color;
};

layout(set = 1, binding = 1) uniform sampler2D material_tex;

layout(location = 0) out vec4 outColor;

void main() {
  float light = texture(light_tex, gl_FragCoord.xy * frag_coord_to_uv_multiplier).r;
  // Hacked in ambient (maybe the ambient_light_intensity above works, maybe it
  // doesn't, who knows?)
  const float ambient = 0.7;
  light = ambient + (1 - ambient) * light;
  outColor = light * color * texture(material_tex, inUV);
}
)GLSL";

ModelLightingPass::ModelLightingPass(ResourceRecycler* recycler,
                                     ModelDataPtr model_data,
                                     vk::Format color_format,
                                     vk::Format depth_format,
                                     uint32_t sample_count)
    : ModelRenderPass(recycler, color_format, depth_format, sample_count) {
  vk::AttachmentDescription* color_attachment =
      attachment(kColorAttachmentIndex);
  vk::AttachmentDescription* depth_attachment =
      attachment(kDepthAttachmentIndex);

  color_attachment->loadOp = vk::AttachmentLoadOp::eClear;
  // TODO: necessary to store if we resolve as part of the render-pass?
  color_attachment->storeOp = vk::AttachmentStoreOp::eStore;
  color_attachment->initialLayout = vk::ImageLayout::eColorAttachmentOptimal;
  color_attachment->finalLayout = vk::ImageLayout::eColorAttachmentOptimal;
  depth_attachment->loadOp = vk::AttachmentLoadOp::eClear;
  depth_attachment->storeOp = vk::AttachmentStoreOp::eDontCare;
  depth_attachment->initialLayout = vk::ImageLayout::eUndefined;
  depth_attachment->finalLayout =
      vk::ImageLayout::eDepthStencilAttachmentOptimal;

  // We have finished specifying the render-pass.  Now create it.
  CreateRenderPassAndPipelineCache(std::move(model_data));
}

std::string ModelLightingPass::GetFragmentShaderSourceCode(
    const ModelPipelineSpec& spec) {
  return kFragmentShaderSourceCode;
}

std::string ModelLightingPass::GetVertexShaderMainSourceCode() {
  return kVertexShaderMainSourceCode;
}

}  // namespace impl
}  // namespace escher