# PrimitiveShadingRateKHR(3) Manual Page

## Name

PrimitiveShadingRateKHR - Primitive contribution to fragment shading rate

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## 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.

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 for all supported execution models except `MeshEXT`

- 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

- VUID-PrimitiveShadingRateKHR-PrimitiveShadingRateKHR-10598
  `PrimitiveShadingRateKHR` within the `MeshEXT` `Execution` `Model` must decorate a scalar 32-bit integer member of a structure decorated as `Block`, or decorate a variable of type `OpTypeArray` of 32-bit integer values

- VUID-PrimitiveShadingRateKHR-PrimitiveShadingRateKHR-10599
  If `PrimitiveShadingRateKHR` is declared as an array of 32-bit integer values, within the `MeshEXT` `Execution` `Model`, size of the array must match the value specified by `OutputPrimitivesEXT`

- VUID-PrimitiveShadingRateKHR-PrimitiveShadingRateKHR-10600
  If `PrimitiveShadingRateKHR` decorates a member of a structure, the variable declaration of the containing `Block` type must have an array size that matches the value specified by `OutputPrimitivesEXT`

- VUID-PrimitiveShadingRateKHR-PrimitiveShadingRateKHR-12275
  If `PrimitiveShadingRateKHR` is declared in the `MeshEXT` `Execution` `Model`, the primitiveFragmentShadingRateMeshShader feature must be enabled

## 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 2014-2026 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0