glReadBuffer — select a color buffer source for pixels
void glReadBuffer( | GLenum | mode); |
mode
Specifies a color buffer.
Accepted values are
GL_FRONT_LEFT,
GL_FRONT_RIGHT,
GL_BACK_LEFT,
GL_BACK_RIGHT,
GL_FRONT,
GL_BACK,
GL_LEFT,
GL_RIGHT, and
GL_AUXi,
where i is between 0 and the value of GL_AUX_BUFFERS minus 1.
glReadBuffer specifies a color buffer as the source for subsequent
glReadPixels, glCopyTexImage1D, glCopyTexImage2D,
glCopyTexSubImage1D, glCopyTexSubImage2D,
glCopyTexSubImage3D, and
glCopyPixels commands.
mode accepts one of twelve or more predefined values.
(GL_AUX0 through GL_AUX3 are always defined.)
In a fully configured system,
GL_FRONT,
GL_LEFT, and
GL_FRONT_LEFT all name the front left buffer,
GL_FRONT_RIGHT and
GL_RIGHT name the front right buffer, and
GL_BACK_LEFT and
GL_BACK name the back left buffer.
Nonstereo double-buffered configurations have only a front left and a
back left buffer.
Single-buffered configurations have a front left and a front right
buffer if stereo, and only a front left buffer if nonstereo.
It is an error to specify a nonexistent buffer to glReadBuffer.
mode is initially GL_FRONT in single-buffered configurations
and GL_BACK in double-buffered configurations.
GL_INVALID_ENUM is generated if mode is not one of the twelve
(or more) accepted values.
GL_INVALID_OPERATION is generated if mode specifies a buffer
that does not exist.
GL_INVALID_OPERATION is generated if glReadBuffer
is executed between the execution of glBegin
and the corresponding execution of glEnd.
glCopyPixels, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, glCopyTexSubImage3D, glDrawBuffer, glReadPixels
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/.