- specify which color buffers are to be drawn into



C SPECIFICATION


PARAMETERS

       _param1  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  con-
                texts.


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
                                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  pro-
       duce different results in each buffer.

       Monoscopic contexts include only left buffers, and stereo-
       scopic 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 initial-
       ization.


NOTES

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


ERRORS

       GL_INVALID_ENUM is generated if _param1 is not an accepted
       value.

       GL_INVALID_OPERATION  is  generated if none of the buffers
       indicated by _param1 exists.

       GL_INVALID_OPERATION is generated if glDrawBuffer is  exe-
       cuted between the execution of glBegin and the correspond-
       ing execution of glEnd.


ASSOCIATED GETS

       glGet with argument GL_DRAW_BUFFER
       glGet with argument GL_AUX_BUFFERS


SEE ALSO

       glBlendFunc,    glColorMask,    glIndexMask,    glLogicOp,
       glReadBuffer



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