glDrawBuffer(3G)	       OpenGL Reference		      glDrawBuffer(3G)

NAME    [Toc]    [Back]

     glDrawBuffer - specify which color	buffers	are to be drawn	into

C SPECIFICATION    [Toc]    [Back]

     void glDrawBuffer(	GLenum mode )

PARAMETERS    [Toc]    [Back]

     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    [Toc]    [Back]

     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.



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glDrawBuffer(3G)	       OpenGL Reference		      glDrawBuffer(3G)



     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    [Toc]    [Back]

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

ERRORS    [Toc]    [Back]

     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    [Toc]    [Back]

     glGet with	argument GL_DRAW_BUFFER
     glGet with	argument GL_AUX_BUFFERS

SEE ALSO    [Toc]    [Back]

     glBlendFunc, glColorMask, glIndexMask, glLogicOp, glReadBuffer


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