glDrawBuffer 4YR2_QM

[New - Windows 95, OEM Service Release 2]

The glDrawBuffer function specifies which color buffers are to be drawn into.

void glDrawBuffer(

GLenum mode
);

Parameters

mode

Specifies up to four color buffers to be drawn into with the following acceptable symbolic constants:

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 the auxiliary color buffer i is written; i is between 0 and GL_AUX_BUFFERS -1. (GL_AUX_BUFFERS is not the upper limit; use glGet8KNKTW 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.

Remarks

When colors are written to the frame buffer, they are written into the color buffers specified by glDrawBuffer.

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 OpenGL initialization.

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

The following functions retrieve information related to the glDrawBuffer function:

glGet8KNKTW with argument GL_DRAW_BUFFER

glGet with argument GL_AUX_BUFFERS

Error Codes

The following are the error codes generated and their conditions.

Error Code	Condition
GL_INVALID_ENUM	mode was not an accepted value.
GL_INVALID_OPERATION	None of the buffers indicated by mode existed.
GL_INVALID_OPERATION	glDrawBuffer was called between a call to glBegin and the corresponding call to glEnd.