FragCoord(3)

# FragCoord(3) Manual Page

## Name

FragCoord - Screen-space coordinate of the fragment center

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## Description

`FragCoord`

  Decorating a variable with the `FragCoord` built-in decoration will make that variable contain the framebuffer coordinate (x, y, z, w 1​) of the fragment being processed. The (x,y) coordinate (0,0) is the upper left corner of the upper left pixel in the framebuffer.

  When Sample Shading is enabled, the x and y components of `FragCoord` reflect the location of one of the samples corresponding to the shader invocation.

  Otherwise, the x and y components of `FragCoord` reflect the location of the center of the fragment.

  The z component of `FragCoord` is the interpolated depth value of the primitive.

  The w component is the interpolated w 1​.

  The `Centroid` interpolation decoration is ignored, but allowed, on `FragCoord`.

Valid Usage

- VUID-FragCoord-FragCoord-04210
  The `FragCoord` decoration must be used only within the `Fragment` `Execution` `Model`

- VUID-FragCoord-FragCoord-04211
  The variable decorated with `FragCoord` must be declared using the `Input` `Storage` `Class`

- VUID-FragCoord-FragCoord-04212
  The variable decorated with `FragCoord` must be declared as a four-component vector of 32-bit floating-point values

## 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 2014-2022 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0