329 lines
9.8 KiB
ReStructuredText
329 lines
9.8 KiB
ReStructuredText
Zink
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====
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Overview
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--------
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The Zink driver is a Gallium driver that emits Vulkan API calls instead
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of targeting a specific GPU architecture. This can be used to get full
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desktop OpenGL support on devices that only support Vulkan.
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Features
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--------
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The feature-level of Zink depends on two things; what's implemented in Zink,
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as well as the features of the Vulkan driver.
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OpenGL 2.1
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^^^^^^^^^^
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OpenGL 2.1 is the minimum version Zink can support, and will always be
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exposed, given Vulkan support. There's a few features that are required
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for correct behavior, but not all of these are validated; instead you'll
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see rendering-issues and likely validation error, or even crashes.
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Here's a list of those requirements:
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* Vulkan 1.0
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* ``VkPhysicalDeviceFeatures``:
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* ``logicOp``
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* ``fillModeNonSolid``
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* ``alphaToOne``
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* ``shaderClipDistance``
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* Device extensions:
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* `VK_KHR_maintenance1`_
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* `VK_KHR_create_renderpass2`_
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* `VK_KHR_imageless_framebuffer`_
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* `VK_KHR_timeline_semaphore`_
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* `VK_EXT_custom_border_color`_ with ``customBorderColorWithoutFormat``
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* `VK_EXT_provoking_vertex`_
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* `VK_EXT_line_rasterization`_, with the following ``VkPhysicalDeviceLineRasterizationFeaturesEXT``:
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* ``rectangularLines``
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* ``bresenhamLines``
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* ``smoothLines``
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* ``stippledRectangularLines``
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* ``stippledBresenhamLines``
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* ``stippledSmoothLines``
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* `VK_KHR_swapchain_mutable_format`_
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* `VK_EXT_border_color_swizzle`_
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In addition to this, `VK_KHR_external_memory`_ is required to support the
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DRI code-path.
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We also require either the `VK_EXT_scalar_block_layout`_ extension or
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Vulkan 1.2, with the ``scalarBlockLayout`` feature.
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OpenGL 3.0
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^^^^^^^^^^
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For OpenGL 3.0 support, the following additional requirements must be
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supported:
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* ``VkPhysicalDeviceFeatures``:
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* ``independentBlend``
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* Device extensions:
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* `VK_EXT_transform_feedback`_
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* `VK_EXT_conditional_rendering`_
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OpenGL 3.1
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^^^^^^^^^^
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For OpenGL 3.1 support, the following additional ``VkPhysicalDeviceLimits``
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are required:
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* ``maxPerStageDescriptorSamplers`` ≥ 16
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OpenGL 3.2
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^^^^^^^^^^
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For OpenGL 3.2 support, the following additional requirements must be
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supported, although some of these might not actually get verified:
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* ``VkPhysicalDeviceFeatures``:
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* ``depthClamp``
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* ``geometryShader``
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* ``shaderTessellationAndGeometryPointSize``
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* Device extensions:
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* `VK_EXT_depth_clip_enable`_
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OpenGL 3.3
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^^^^^^^^^^
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For OpenGL 3.3 support, the following additional requirements must be
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supported, although some of these might not actually get verified:
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* ``VkPhysicalDeviceFeatures``:
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* ``occlusionQueryPrecise``
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* Device extensions:
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* `VK_EXT_vertex_attribute_divisor`_
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OpenGL 4.0
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^^^^^^^^^^
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For OpenGL 4.0 support, the following additional requirements must be
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supported:
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* ``VkPhysicalDeviceFeatures``:
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* ``sampleRateShading``
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* ``tessellationShader``
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* ``imageCubeArray``
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* Device extensions:
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* `VK_KHR_maintenance2`_
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* Formats requiring ``VK_FORMAT_FEATURE_UNIFORM_TEXEL_BUFFER_BIT``:
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* ``VK_FORMAT_R32G32B32_SFLOAT``
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* ``VK_FORMAT_R32G32B32_SINT``
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* ``VK_FORMAT_R32G32B32_UINT``
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OpenGL 4.1
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^^^^^^^^^^
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For OpenGL 4.1 support, the following additional requirements must be
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supported:
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* ``VkPhysicalDeviceFeatures``:
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* ``multiViewport``
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* ``VkPhysicalDeviceLimits``
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* ``maxImageDimension2D`` ≥ 16384
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* ``maxViewports`` ≥ 16
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OpenGL 4.2
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^^^^^^^^^^
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For OpenGL 4.2 support, the following additional requirements must be
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supported:
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* Device extensions:
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* `VK_EXT_image_2d_view_of_3d`_
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* ``VkPhysicalDeviceLimits``:
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* ``shaderStorageImageExtendedFormats``
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* ``shaderStorageImageWriteWithoutFormat``
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* For Vulkan 1.2 and above:
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* ``VkPhysicalDeviceVulkan11Features``:
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* ``shaderDrawParameters``
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* ``vertexPipelineStoresAndAtomics``
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* ``fragmentStoresAndAtomics``
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* ``textureCompressionBC``
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* For Vulkan 1.1 and below:
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* Device extensions:
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* `VK_KHR_shader_draw_parameters`_
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* Formats requiring ``VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT``:
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* ``VK_FORMAT_BC7_UNORM_BLOCK``
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* ``VK_FORMAT_BC7_SRGB_BLOCK``
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* ``VK_FORMAT_BC6H_SFLOAT_BLOCK``
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* ``VK_FORMAT_BC6H_UFLOAT_BLOCK``
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OpenGL 4.3
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^^^^^^^^^^
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For OpenGL 4.3 support, the following additional requirements must be
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supported:
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* ``VkPhysicalDeviceFeatures``:
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* ``robustBufferAccess``
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* Formats requiring ``VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT``:
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* ``VK_FORMAT_R8G8B8A8_UNORM``
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* ``VK_FORMAT_R8G8B8A8_SRGB``
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* ``VK_FORMAT_R16_UNORM``
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* ``VK_FORMAT_R16G16_UNORM``
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* ``VK_FORMAT_R16_SNORM``
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* ``VK_FORMAT_R16G16_SNORM``
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* ``VK_FORMAT_D32_SFLOAT_S8_UINT``
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OpenGL 4.4
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^^^^^^^^^^
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For OpenGL 4.4 support, the following additional requirements must be
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supported:
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* Formats requiring ``VK_FORMAT_FEATURE_VERTEX_BUFFER_BIT``:
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* ``VK_FORMAT_B10G11R11_UFLOAT_PACK32``
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* Device extensions:
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* `VK_KHR_sampler_mirror_clamp_to_edge`_
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OpenGL 4.5
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^^^^^^^^^^
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For OpenGL 4.5 support, the following additional ``VkPhysicalDeviceFeatures``
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are required to be supported
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* ``shaderCullDistance``
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OpenGL 4.6
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^^^^^^^^^^
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For OpenGL 4.6 support, the following additional ``VkPhysicalDeviceFeatures``
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are required to be supported
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* ``VkPhysicalDeviceFeatures``:
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* ``samplerAnisotropy``
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* ``pipelineStatisticsQuery``
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* ``depthBiasClamp``
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* Device extensions:
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* `VK_KHR_draw_indirect_count`_
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Performance
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-----------
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If you notice poor performance and high CPU usage while running an application,
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changing the descriptor manager may improve performance:
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.. envvar:: ZINK_DESCRIPTORS <mode> ("auto")
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``auto``
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Automatically detect best mode. This is the default.
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``lazy``
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Disable caching and attempt to use the least amount of CPU.
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``cached``
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Use caching to reuse descriptor sets.
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``notemplates``
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The same as `auto`, but disables the use of `VK_KHR_descriptor_templates`.
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Debugging
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---------
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There's a few tools that are useful for debugging Zink, like this environment
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variable:
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.. envvar:: ZINK_DEBUG <flags> ("")
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``nir``
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Print the NIR form of all shaders to stderr.
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``spirv``
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Write the binary SPIR-V form of all compiled shaders to a file in the
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current directory, and print a message with the filename to stderr.
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``tgsi``
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Print the TGSI form of TGSI shaders to stderr.
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``validation``
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Dump Validation layer output.
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``sync``
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Emit full synchronization barriers before every draw and dispatch.
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``compact``
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Use a maximum of 4 descriptor sets
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``noreorder``
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Do not reorder or optimize GL command streams
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Vulkan Validation Layers
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^^^^^^^^^^^^^^^^^^^^^^^^
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Another useful tool for debugging is the `Vulkan Validation Layers
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<https://github.com/KhronosGroup/Vulkan-ValidationLayers/blob/master/README.md>`_.
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The validation layers effectively insert extra checking between Zink and the
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Vulkan driver, pointing out incorrect usage of the Vulkan API. The layers can
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be enabled by setting the environment variable :envvar:`VK_INSTANCE_LAYERS` to
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"VK_LAYER_KHRONOS_validation". You can read more about the Validation Layers
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in the link above.
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IRC
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---
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In order to make things a bit easier to follow, we have decided to create our
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own IRC channel. If you're interested in contributing, or have any technical
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questions, don't hesitate to visit `#zink on OFTC
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<irc://irc.oftc.net/zink>`__ and say hi!
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.. _VK_KHR_maintenance1: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_maintenance1.html
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.. _VK_KHR_create_renderpass2: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_create_renderpass2.html
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.. _VK_KHR_imageless_framebuffer: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_imageless_framebuffer.html
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.. _VK_KHR_timeline_semaphore: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_timeline_semaphore.html
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.. _VK_KHR_external_memory: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_external_memory.html
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.. _VK_EXT_scalar_block_layout: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_scalar_block_layout.html
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.. _VK_EXT_transform_feedback: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_transform_feedback.html
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.. _VK_EXT_conditional_rendering: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_conditional_rendering.html
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.. _VK_EXT_vertex_attribute_divisor: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_vertex_attribute_divisor.html
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.. _VK_EXT_image_2d_view_of_3d: https://www.khronos.org/registry/vulkan/specs/1.3-extensions/man/html/VK_EXT_image_2d_view_of_3d.html
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.. _VK_KHR_maintenance2: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_maintenance2.html
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.. _VK_KHR_shader_draw_parameters: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_shader_draw_parameters.html
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.. _VK_KHR_draw_indirect_count: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_draw_indirect_count.html
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.. _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
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.. _VK_EXT_custom_border_color: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_custom_border_color.html
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.. _VK_EXT_provoking_vertex: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_provoking_vertex.html
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.. _VK_EXT_line_rasterization: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_line_rasterization.html
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.. _VK_KHR_swapchain_mutable_format: https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VK_KHR_swapchain_mutable_format.html
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.. _VK_EXT_border_color_swizzle: https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VK_EXT_border_color_swizzle.html
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.. _VK_EXT_depth_clip_enable: https://www.khronos.org/registry/vulkan/specs/1.3-extensions/man/html/VK_EXT_depth_clip_enable.html
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