1991-2006
Silicon Graphics, Inc.
glClear
3G

# glClear

clear buffers to preset values

## C Specification

                    void glClear
                    GLbitfield mask

## Parameters

`mask`

  Bitwise OR of masks that indicate the buffers to be cleared. The four masks are `GL_COLOR_BUFFER_BIT`, `GL_DEPTH_BUFFER_BIT`, `GL_ACCUM_BUFFER_BIT`, and `GL_STENCIL_BUFFER_BIT`.

## Description

`glClear` sets the bitplane area of the window to values previously selected by `glClearColor`, `glClearIndex`, `glClearDepth`, `glClearStencil`, and `glClearAccum`. Multiple color buffers can be cleared simultaneously by selecting more than one buffer at a time using glDrawBuffer.

The pixel ownership test, the scissor test, dithering, and the buffer writemasks affect the operation of `glClear`. The scissor box bounds the cleared region. Alpha function, blend function, logical operation, stenciling, texture mapping, and depth-buffering are ignored by `glClear`.

`glClear` takes a single argument that is the bitwise OR of several values indicating which buffer is to be cleared.

The values are as follows:

`GL_COLOR_BUFFER_BIT`

  Indicates the buffers currently enabled for color writing.

`GL_DEPTH_BUFFER_BIT`

  Indicates the depth buffer.

`GL_ACCUM_BUFFER_BIT`

  Indicates the accumulation buffer.

`GL_STENCIL_BUFFER_BIT`

  Indicates the stencil buffer.

The value to which each buffer is cleared depends on the setting of the clear value for that buffer.

## Notes

If a buffer is not present, then a `glClear` directed at that buffer has no effect.

## Errors

`GL_INVALID_VALUE` is generated if any bit other than the four defined bits is set in `mask`.

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

## Associated Gets

glGet with argument `GL_ACCUM_CLEAR_VALUE`

glGet with argument `GL_DEPTH_CLEAR_VALUE`

glGet with argument `GL_INDEX_CLEAR_VALUE`

glGet with argument `GL_COLOR_CLEAR_VALUE`

glGet with argument `GL_STENCIL_CLEAR_VALUE`

## See Also

`glClearAccum`, `glClearColor`, `glClearDepth`, `glClearIndex`, `glClearStencil`, glColorMask, glDepthMask, glDrawBuffer, glScissor, glStencilMask

## Copyright

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