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# docs.GL

OpenGL 3
OpenGL 2

# glIndexMask

## Name

glIndexMask — control the writing of individual bits in the color index buffers

## C Specification

`void glIndexMask(` | GLuint | mask`)`;

## Parameters

`mask`

  Specifies a bit mask to enable and disable the writing of individual bits in the color index buffers. Initially, the mask is all 1's.

## Description

`glIndexMask` controls the writing of individual bits in the color index buffers. The least significant n bits of `mask`, where n is the number of bits in a color index buffer, specify a mask. Where a 1 (one) appears in the mask, it's possible to write to the corresponding bit in the color index buffer (or buffers). Where a 0 (zero) appears, the corresponding bit is write-protected.

This mask is used only in color index mode, and it affects only the buffers currently selected for writing (see glDrawBuffer). Initially, all bits are enabled for writing.

## Errors

`GL_INVALID_OPERATION` is generated if `glIndexMask` is executed between the execution of glBegin and the corresponding execution of glEnd.

## Associated Gets

glGet with argument `GL_INDEX_WRITEMASK`

## See Also

glColorMask, glDepthMask, glDrawBuffer, glIndex, glIndexPointer, glStencilMask

## Copyright

Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see https://web.archive.org/web/20171022161616/http://oss.sgi.com/projects/FreeB/.

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