glDrawBuffer

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 GL_AUX_BUFFERS -1, are accepted (GL_AUX_BUFFERS is not the upper limit; use glGet to query the number of available aux buffers.) The default 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_AUXi = 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 called between a call to glBegin and the corresponding call to glEnd.

ASSOCIATED GETS

glGet with argument GL_DRAW_BUFFER

glGet with argument GL_AUX_BUFFERS