GLDRAWBUFFER(3G)

NAME
glDrawBuffer - specify which color buffers are to be drawn into

C SPECIFICATION

void glDrawBuffer(GLenum mode);

PARAMETERS

mode
    Specifies up to four color buffers to be drawn into. Symbolic constants GL_NONE, GL_FRONT_LEFT, GL_FRONT_RIGHT, GL_BACK_LEFT, GL_BACK_RIGHT, GL_FRONT, GL_BACK, GL_LEFT, GL_RIGHT, GL_FRONT_AND_BACK, and GL_AUXi, where i is between 0 and the value of GL_AUX_BUFFERS minus 1, are accepted. (GL_AUX_BUFFERS is not the upper limit; use glGet() to query the number of available aux buffers.) The initial value is GL_FRONT for single-buffered contexts, and GL_BACK for double-buffered contexts.

DESCRIPTION

When colors are written to the frame buffer, they are written into the color buffers specified by glDrawBuffer. The specifications are as follows:

GL_NONE
    No color buffers are written.

GL_FRONT_LEFT
    Only the front left color buffer is written.

GL_FRONT_RIGHT
    Only the front right color buffer is written.

GL_BACK_LEFT
    Only the back left color buffer is written.

GL_BACK_RIGHT
    Only the back right color buffer is written.

GL_FRONT
    Only the front left and front right color buffers are written. If there is no front right color buffer, only the front left color buffer is written.

GL_BACK
    Only the back left and back right color buffers are written. If there is no back right color buffer, only the back left color buffer is written.

GL_LEFT
    Only the front left and back left color buffers are written. If there is no back left color buffer, only the front left color buffer is written.

GL_RIGHT
    Only the front right and back right color buffers are written. If there is no back right color buffer, only the front right color buffer is written.

GL_FRONT_AND_BACK
    All the front and back color buffers (front left, front right, back left, back right) are written. If there are no back color buffers, only the front left and front right color buffers are written. If there are no right color buffers, only the front left and back left color buffers are written. If there are no right or back color buffers, only the front left color buffer is written.

GL_AUXi
    Only auxiliary color buffer i is written.

If more than one color buffer is selected for drawing, then blending or logical operations are computed and applied independently for each color buffer and can produce different results in each buffer.

Monoscopic contexts include only left buffers, and stereoscopic contexts include both left and right buffers. Likewise, single-buffered contexts include only front buffers, and double-buffered contexts include both front and back buffers. The context is selected at GL initialization.

NOTES

It is always the case that GL_AUX i = GL_AUX0 + i.

ERRORS

GL_INVALID_ENUM is generated if mode is not an accepted value.

GL_INVALID_OPERATION is generated if none of the buffers indicated by mode exists.

GL_INVALID_OPERATION is generated if glDrawBuffer is executed between the execution of glBegin() and the corresponding execution of glEnd().

ASSOCIATED GETS

glGet() with argument GL_DRAW_BUFFER

glGet() with argument GL_AUX_BUFFERS

SEE ALSO

glBlendFunc(), glColorMask(), glIndexMask(), glLogicOp(), glReadBuffer()

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/.