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 the constants
GL_COLOR_ATTACHMENTi
.
glReadBuffer
specifies a color buffer as the source for subsequent
glReadPixels, glCopyTexImage1D, glCopyTexImage2D,
glCopyTexSubImage1D, glCopyTexSubImage2D, and
glCopyTexSubImage3D commands.
mode
accepts one of twelve or more predefined values.
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.
Further more, the constants GL_COLOR_ATTACHMENTi
may be used to indicate the
ith color attachment where i ranges from zero to the
value of GL_MAX_COLOR_ATTACHMENTS
minus one.
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.
glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, glCopyTexSubImage3D, glDrawBuffer, glReadPixels
Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2011 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.