glDrawBuffer(3G)

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 initial 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 executed between the
     execution of glBegin and the corresponding execution of glEnd.

ASSOCIATED GETS
     glGet with argument GL_DRAW_BUFFER
     glGet with argument GL_AUX_BUFFERS


SEE ALSO
     glBlendFunc, glColorMask, glIndexMask, glLogicOp, glReadBuffer