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, 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.
Furthermore, 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
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