glDrawBuffer

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:

  Constant	Description
  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 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.

Remarks

When colors are written to the framebuffer, 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:

glGet 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.

Requirements

**  Windows NT/2000:** Requires Windows NT 3.5 or later.
**  Windows 95/98:** Requires Windows 95 or later. Available as a redistributable for Windows 95.
**  Header:** Declared in Gl.h.
**  Library:** Use Opengl32.lib.

See Also

glBegin, glBlendFunc, glColorMask, glEnd, glGet, glIndexMask, glLogicOp, glReadBuffer