Description

PrimitiveShadingRateKHR

Decorating a variable with the PrimitiveShadingRateKHR built-in decoration will make that variable contain the primitive fragment shading rate.

The value written to the variable decorated with PrimitiveShadingRateKHR by the last pre-rasterization shader stage in the pipeline is used as the primitive fragment shading rate. Outputs in previous shader stages are ignored.

If the last active pre-rasterization shader stage shader entry point’s interface does not include a variable decorated with PrimitiveShadingRateKHR, then it is as if the shader specified a fragment shading rate value of 0, indicating a horizontal and vertical rate of 1 pixel.

If a shader has PrimitiveShadingRateKHR in the output interface and there is an execution path through the shader that does not write to it, its value is undefined for executions of the shader that take that path.

Valid Usage

  • VUID-PrimitiveShadingRateKHR-PrimitiveShadingRateKHR-04484
    The PrimitiveShadingRateKHR decoration must be used only within the MeshEXT, MeshNV, Vertex, or Geometry Execution Model

  • VUID-PrimitiveShadingRateKHR-PrimitiveShadingRateKHR-04485
    The variable decorated with PrimitiveShadingRateKHR must be declared using the Output Storage Class

  • VUID-PrimitiveShadingRateKHR-PrimitiveShadingRateKHR-04486
    The variable decorated with PrimitiveShadingRateKHR must be declared as a scalar 32-bit integer value

  • VUID-PrimitiveShadingRateKHR-PrimitiveShadingRateKHR-04487
    The value written to PrimitiveShadingRateKHR must include no more than one of Vertical2Pixels and Vertical4Pixels

  • VUID-PrimitiveShadingRateKHR-PrimitiveShadingRateKHR-04488
    The value written to PrimitiveShadingRateKHR must include no more than one of Horizontal2Pixels and Horizontal4Pixels

  • VUID-PrimitiveShadingRateKHR-PrimitiveShadingRateKHR-04489
    The value written to PrimitiveShadingRateKHR must not have any bits set other than those defined by Fragment Shading Rate Flags enumerants in the SPIR-V specification

  • VUID-PrimitiveShadingRateKHR-PrimitiveShadingRateKHR-07059
    The variable decorated with PrimitiveShadingRateKHR within the MeshEXT Execution Model must also be decorated with the PerPrimitiveEXT decoration

See Also

No cross-references are available

Document Notes

For more information, see the Vulkan Specification

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

Copyright

Copyright 2014-2024 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0