| Zink |
| ==== |
| |
| Overview |
| -------- |
| |
| The Zink driver is a Gallium driver that emits Vulkan API calls instead |
| of targeting a specific GPU architecture. This can be used to get full |
| desktop OpenGL support on devices that only support Vulkan. |
| |
| Features |
| -------- |
| |
| The feature-level of Zink depends on two things; what's implemented in Zink, |
| as well as the features of the Vulkan driver. |
| |
| OpenGL 2.1 |
| ^^^^^^^^^^ |
| |
| OpenGL 2.1 is the minimum version Zink can support, and will always be |
| exposed, given Vulkan support. There's a few features that are required |
| for correct behavior, but not all of these are validated; instead you'll |
| see rendering-issues and likely validation error, or even crashes. |
| |
| Here's a list of those requirements: |
| |
| * Vulkan 1.0 |
| * ``VkPhysicalDeviceFeatures``: |
| |
| * ``logicOp`` |
| * ``fillModeNonSolid`` |
| * ``wideLines`` |
| * ``largePoints`` |
| * ``alphaToOne`` |
| * ``shaderClipDistance`` |
| |
| * Device extensions: |
| |
| * `VK_KHR_maintenance1`_ |
| * `VK_EXT_custom_border_color`_ |
| * `VK_EXT_provoking_vertex`_ |
| * `VK_EXT_line_rasterization`_, with the following ``VkPhysicalDeviceLineRasterizationFeaturesEXT``: |
| |
| * ``rectangularLines`` |
| * ``bresenhamLines`` |
| * ``smoothLines`` |
| * ``stippledRectangularLines`` |
| * ``stippledBresenhamLines`` |
| * ``stippledSmoothLines`` |
| |
| In addition to this, `VK_KHR_external_memory`_ is required to support the |
| DRI code-path. |
| |
| We also require either the `VK_EXT_scalar_block_layout`_ extension or |
| Vulkan 1.2, with the ``scalarBlockLayout`` feature. |
| |
| OpenGL 3.0 |
| ^^^^^^^^^^ |
| |
| |
| For OpenGL 3.0 support, the following additional requirements needs to be |
| supported: |
| |
| * ``VkPhysicalDeviceFeatures``: |
| |
| * ``independentBlend`` |
| |
| * Device extensions: |
| |
| * `VK_EXT_transform_feedback`_ |
| * `VK_EXT_conditional_rendering`_ |
| |
| |
| OpenGL 3.1 |
| ^^^^^^^^^^ |
| |
| For OpenGL 3.1 support, the following additional ``VkPhysicalDeviceLimits`` |
| are required: |
| |
| * ``maxPerStageDescriptorSamplers`` ≥ 16 |
| |
| OpenGL 3.2 |
| ^^^^^^^^^^ |
| |
| For OpenGL 3.2 support, the following additional ``VkPhysicalDeviceFeatures`` |
| are required to be supported, although some of these might not actually get |
| verified: |
| |
| * ``depthClamp`` |
| * ``geometryShader`` |
| * ``shaderTessellationAndGeometryPointSize`` |
| |
| OpenGL 3.3 |
| ^^^^^^^^^^ |
| |
| For OpenGL 3.3 support, the following additional requirements needs to be |
| supported, although some of these might not actually get verified: |
| |
| * ``VkPhysicalDeviceFeatures``: |
| |
| * ``occlusionQueryPrecise`` |
| |
| * Device extensions: |
| |
| * `VK_EXT_vertex_attribute_divisor`_ |
| |
| OpenGL 4.0 |
| ^^^^^^^^^^ |
| |
| For OpenGL 4.0 support, the following additional requirements needs to be |
| supported: |
| |
| * ``VkPhysicalDeviceFeatures``: |
| |
| * ``sampleRateShading`` |
| * ``tessellationShader`` |
| * ``imageCubeArray`` |
| |
| * Device extensions: |
| |
| * `VK_KHR_maintenance2`_ |
| |
| * Formats requiring ``VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT``: |
| |
| * ``VK_FORMAT_R32G32B32_SFLOAT`` |
| * ``VK_FORMAT_R32G32B32_SINT`` |
| * ``VK_FORMAT_R32G32B32_UINT`` |
| |
| OpenGL 4.1 |
| ^^^^^^^^^^ |
| |
| For OpenGL 4.1 support, the following additional ``VkPhysicalDeviceLimits`` |
| are required: |
| |
| * ``maxImageDimension2D`` ≥ 16384 |
| * ``maxViewports`` ≥ 16 |
| |
| OpenGL 4.2 |
| ^^^^^^^^^^ |
| |
| For OpenGL 4.2 support, the following additional requirements needs to be |
| supported: |
| |
| * ``VkPhysicalDeviceLimits``: |
| |
| * ``shaderStorageImageExtendedFormats`` |
| * ``shaderStorageImageWriteWithoutFormat`` |
| |
| * For Vulkan 1.2 and above: |
| |
| * ``VkPhysicalDeviceVulkan11Features``: |
| |
| * ``shaderDrawParameters`` |
| * ``vertexPipelineStoresAndAtomics`` |
| * ``fragmentStoresAndAtomics`` |
| * ``textureCompressionBC`` |
| |
| * For Vulkan 1.1 and below: |
| |
| * Device extensions: |
| |
| * `VK_KHR_shader_draw_parameters`_ |
| |
| * Formats requiring ``VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT``: |
| |
| * ``VK_FORMAT_BC7_UNORM_BLOCK`` |
| * ``VK_FORMAT_BC7_SRGB_BLOCK`` |
| * ``VK_FORMAT_BC6H_SFLOAT_BLOCK`` |
| * ``VK_FORMAT_BC6H_UFLOAT_BLOCK`` |
| |
| OpenGL 4.3 |
| ^^^^^^^^^^ |
| |
| For OpenGL 4.3 support, the following additional requirements needs to be |
| supported: |
| |
| * ``VkPhysicalDeviceFeatures``: |
| |
| * ``robustBufferAccess`` |
| * ``multiViewport`` |
| |
| * Formats requiring ``VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT``: |
| |
| * ``VK_FORMAT_R8G8B8A8_UNORM`` |
| * ``VK_FORMAT_R8G8B8A8_SRGB`` |
| * ``VK_FORMAT_R16_UNORM`` |
| * ``VK_FORMAT_R16G16_UNORM`` |
| * ``VK_FORMAT_R16_SNORM`` |
| * ``VK_FORMAT_R16G16_SNORM`` |
| * ``VK_FORMAT_D32_SFLOAT_S8_UINT`` |
| |
| OpenGL 4.4 |
| ^^^^^^^^^^ |
| |
| For OpenGL 4.4 support, the following additional requirements needs to be |
| supported: |
| |
| * Formats requiring ``VK_FORMAT_FEATURE_VERTEX_BUFFER_BIT``: |
| |
| * ``VK_FORMAT_B10G11R11_UFLOAT_PACK32`` |
| |
| * Device extensions: |
| |
| * `VK_KHR_sampler_mirror_clamp_to_edge`_ |
| |
| OpenGL 4.5 |
| ^^^^^^^^^^ |
| |
| For OpenGL 4.5 support, the following additional ``VkPhysicalDeviceFeatures`` |
| are required to be supported |
| |
| * ``shaderCullDistance`` |
| |
| OpenGL 4.6 |
| ^^^^^^^^^^ |
| |
| For OpenGL 4.6 support, the following additional ``VkPhysicalDeviceFeatures`` |
| are required to be supported |
| |
| * ``VkPhysicalDeviceFeatures``: |
| |
| * ``samplerAnisotropy`` |
| * ``pipelineStatisticsQuery`` |
| * ``depthBiasClamp`` |
| |
| * Device extensions: |
| |
| * `VK_KHR_draw_indirect_count`_ |
| |
| Debugging |
| --------- |
| |
| There's a few tools that are useful for debugging Zink, like this environment |
| variable: |
| |
| .. envvar:: ZINK_DEBUG <flags> ("") |
| |
| ``nir`` |
| Print the NIR form of all shaders to stderr. |
| ``spirv`` |
| Write the binary SPIR-V form of all compiled shaders to a file in the |
| current directory, and print a message with the filename to stderr. |
| ``tgsi`` |
| Print the TGSI form of TGSI shaders to stderr. |
| ``validation`` |
| Dump Validation layer output. |
| |
| Vulkan Validation Layers |
| ^^^^^^^^^^^^^^^^^^^^^^^^ |
| |
| Another useful tool for debugging is the `Vulkan Validation Layers |
| <https://github.com/KhronosGroup/Vulkan-ValidationLayers/blob/master/README.md>`_. |
| |
| The validation layers effectively insert extra checking between Zink and the |
| Vulkan driver, pointing out incorrect usage of the Vulkan API. The layers can |
| be enabled by setting the environment variable :envvar:`VK_INSTANCE_LAYERS` to |
| "VK_LAYER_KHRONOS_validation". You can read more about the Validation Layers |
| in the link above. |
| |
| IRC |
| --- |
| |
| In order to make things a bit easier to follow, we have decided to create our |
| own IRC channel. If you're interested in contributing, or have any technical |
| questions, don't hesitate to visit `#zink on OFTC |
| <irc://irc.oftc.net/zink>`__ and say hi! |
| |
| |
| .. _VK_KHR_maintenance1: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_maintenance1.html |
| .. _VK_KHR_external_memory: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_external_memory.html |
| .. _VK_EXT_scalar_block_layout: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_scalar_block_layout.html |
| .. _VK_EXT_transform_feedback: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_transform_feedback.html |
| .. _VK_EXT_conditional_rendering: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_conditional_rendering.html |
| .. _VK_EXT_vertex_attribute_divisor: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_vertex_attribute_divisor.html |
| .. _VK_KHR_maintenance2: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_maintenance2.html |
| .. _VK_KHR_shader_draw_parameters: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_shader_draw_parameters.html |
| .. _VK_KHR_draw_indirect_count: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_draw_indirect_count.html |
| .. _VK_KHR_sampler_mirror_clamp_to_edge: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_sampler_mirror_clamp_to_edge.html |
| .. _VK_EXT_custom_border_color: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_custom_border_color.html |
| .. _VK_EXT_provoking_vertex: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_provoking_vertex.html |
| .. _VK_EXT_line_rasterization: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_line_rasterization.html |