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# docs.GL

GLSL 4
GLSL ES 3

# gl_FragDepth

## Name

gl_FragDepth — establishes a depth value for the current fragment

## Declaration

`out float gl_FragDepth ;`

## Description

Available only in the fragment language, `gl_FragDepth` is an output variable that is used to establish the depth value for the current fragment. If depth buffering is enabled and no shader writes to `gl_FragDepth`, then the fixed function value for depth will be used (this value is contained in the z component of gl_FragCoord) otherwise, the value written to `gl_FragDepth` is used. If a shader statically assigns to `gl_FragDepth`, then the value of the fragment's depth may be undefined for executions of the shader that don't take that path. That is, if the set of linked fragment shaders statically contain a write to `gl_FragDepth`, then it is responsible for always writing it.

## Version Support

| OpenGL Shading Language Version
--- | ---
Variable Name | 1.10 | 1.20 | 1.30 | 1.40 | 1.50 | 3.30 | 4.00 | 4.10 | 4.20 | 4.30 | 4.40 | 4.50
gl_FragDepth | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔

## See Also

gl_FragCoord

## Copyright

Copyright © 2011-2014 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. https://opencontent.org/openpub/.

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