glDrawBuffer

GLDRAWBUFFER(3G)					     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	 con-
       texts  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(3G),	 glColorMask(3G),   glIndexMask(3G),   glLogicOp(3G),
       glReadBuffer(3G)



							     GLDRAWBUFFER(3G)