C Specification

The VkPhysicalDeviceConservativeRasterizationPropertiesEXT structure is defined as:

typedef struct VkPhysicalDeviceConservativeRasterizationPropertiesEXT {
    VkStructureType    sType;
    void*              pNext;
    float              primitiveOverestimationSize;
    float              maxExtraPrimitiveOverestimationSize;
    float              extraPrimitiveOverestimationSizeGranularity;
    VkBool32           primitiveUnderestimation;
    VkBool32           conservativePointAndLineRasterization;
    VkBool32           degenerateTrianglesRasterized;
    VkBool32           degenerateLinesRasterized;
    VkBool32           fullyCoveredFragmentShaderInputVariable;
    VkBool32           conservativeRasterizationPostDepthCoverage;
} VkPhysicalDeviceConservativeRasterizationPropertiesEXT;

Members

The members of the VkPhysicalDeviceConservativeRasterizationPropertiesEXT structure describe the following implementation-dependent limits:

Description

  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • primitiveOverestimationSize is the size in pixels the generating primitive is increased at each of its edges during conservative rasterization overestimation mode. Even with a size of 0.0, conservative rasterization overestimation rules still apply and if any part of the pixel rectangle is covered by the generating primitive, fragments are generated for the entire pixel. However implementations may make the pixel coverage area even more conservative by increasing the size of the generating primitive.

  • maxExtraPrimitiveOverestimationSize is the maximum size in pixels of extra overestimation the implementation supports in the pipeline state. A value of 0.0 means the implementation does not support any additional overestimation of the generating primitive during conservative rasterization. A value above 0.0 allows the application to further increase the size of the generating primitive during conservative rasterization overestimation.

  • extraPrimitiveOverestimationSizeGranularity is the granularity of extra overestimation that can be specified in the pipeline state between 0.0 and maxExtraPrimitiveOverestimationSize inclusive. A value of 0.0 means the implementation can use the smallest representable non-zero value in the screen space pixel fixed-point grid.

  • primitiveUnderestimation is true if the implementation supports the VK_CONSERVATIVE_RASTERIZATION_MODE_UNDERESTIMATE_EXT conservative rasterization mode in addition to VK_CONSERVATIVE_RASTERIZATION_MODE_OVERESTIMATE_EXT. Otherwise the implementation only supports VK_CONSERVATIVE_RASTERIZATION_MODE_OVERESTIMATE_EXT.

  • conservativePointAndLineRasterization is true if the implementation supports conservative rasterization of point and line primitives as well as triangle primitives. Otherwise the implementation only supports triangle primitives.

  • degenerateTrianglesRasterized is false if the implementation culls primitives generated from triangles that become zero area after they are quantized to the fixed-point rasterization pixel grid. degenerateTrianglesRasterized is true if these primitives are not culled and the provoking vertex attributes and depth value are used for the fragments. The primitive area calculation is done on the primitive generated from the clipped triangle if applicable. Zero area primitives are backfacing and the application can enable backface culling if desired.

  • degenerateLinesRasterized is false if the implementation culls lines that become zero length after they are quantized to the fixed-point rasterization pixel grid. degenerateLinesRasterized is true if zero length lines are not culled and the provoking vertex attributes and depth value are used for the fragments.

  • fullyCoveredFragmentShaderInputVariable is true if the implementation supports the SPIR-V builtin fragment shader input variable FullyCoveredEXT which specifies that conservative rasterization is enabled and the fragment area is fully covered by the generating primitive.

  • conservativeRasterizationPostDepthCoverage is true if the implementation supports conservative rasterization with the PostDepthCoverage execution mode enabled. When supported the SampleMask built-in input variable will reflect the coverage after the early per-fragment depth and stencil tests are applied even when conservative rasterization is enabled. Otherwise PostDepthCoverage execution mode must not be used when conservative rasterization is enabled.

If the VkPhysicalDeviceConservativeRasterizationPropertiesEXT structure is included in the pNext chain of VkPhysicalDeviceProperties2, it is filled with the implementation-dependent limits and properties.

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_CONSERVATIVE_RASTERIZATION_PROPERTIES_EXT

See Also

VkBool32, VkStructureType

Document Notes

For more information, see the Vulkan Specification at URL

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

Copyright (c) 2014-2019 Khronos Group. This work is licensed under a Creative Commons Attribution 4.0 International License.