gl_PatchVerticesIn - OpenGL 4 Reference Pages

## Name

gl_PatchVerticesIn — contains the number of vertices in the current patch

## Declaration

`in int gl_PatchVerticesIn ;`

## Description

Available only in the tessellation control and evaluation languages, `gl_PatchVerticesIn` contains the number of vertices in the input being processed by the shader. A single tessellation control or evaluation shader can read patches of differing sizes, and so th value of `gl_PatchVertexIn` may differ between patches.

## 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_PatchVerticesIn | - | - | - | - | - | - | ✔ | ✔ | ✔ | ✔ | ✔ | ✔

## See Also

gl_TessLevelOuter, gl_TessLevelInner, gl_TessCoord

## 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. http://opencontent.org/openpub/.