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<STRONG>NAME</STRONG>
<STRONG>glDrawBuffer</STRONG> - specify which color buffers are to be drawn
into
<STRONG>C</STRONG> <STRONG>SPECIFICATION</STRONG>
void <STRONG>glDrawBuffer</STRONG>( GLenum <EM>mode</EM> )
<STRONG>PARAMETERS</STRONG>
<EM>mode</EM> Specifies up to four color buffers to be drawn into.
Symbolic constants <STRONG>GL_NONE</STRONG>, <STRONG>GL_FRONT_LEFT</STRONG>,
<STRONG>GL_FRONT_RIGHT</STRONG>, <STRONG>GL_BACK_LEFT</STRONG>, <STRONG>GL_BACK_RIGHT</STRONG>, <STRONG>GL_FRONT</STRONG>,
<STRONG>GL_BACK</STRONG>, <STRONG>GL_LEFT</STRONG>, <STRONG>GL_RIGHT</STRONG>, <STRONG>GL_FRONT_AND_BACK</STRONG>, and
<STRONG>GL_AUX</STRONG><EM>i</EM>, where <EM>i</EM> is between 0 and ``<STRONG>GL_AUX_BUFFERS</STRONG>''
-1, are accepted (<STRONG>GL_AUX_BUFFERS</STRONG> is not the upper
limit; use <STRONG>glGet</STRONG> to query the number of available aux
buffers.) The initial value is <STRONG>GL_FRONT</STRONG> for single-
buffered contexts, and <STRONG>GL_BACK</STRONG> for double-buffered
contexts.
<STRONG>DESCRIPTION</STRONG>
When colors are written to the frame buffer, they are
written into the color buffers specified by <STRONG>glDrawBuffer</STRONG>.
The specifications are as follows:
<STRONG>GL_NONE</STRONG> No color buffers are written.
<STRONG>GL_FRONT_LEFT</STRONG> Only the front left color buffer is
written.
<STRONG>GL_FRONT_RIGHT</STRONG> Only the front right color buffer
is written.
<STRONG>GL_BACK_LEFT</STRONG> Only the back left color buffer is
written.
<STRONG>GL_BACK_RIGHT</STRONG> Only the back right color buffer is
written.
<STRONG>GL_FRONT</STRONG> 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.
<STRONG>GL_BACK</STRONG> 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.
<STRONG>GL_LEFT</STRONG> 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.
<STRONG>GL_RIGHT</STRONG> 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.
<STRONG>GL_FRONT_AND_BACK</STRONG> 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.
<STRONG>GL_AUX</STRONG><EM>i</EM> Only auxiliary color buffer <EM>i</EM> 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 <EM>left</EM> buffers, and
stereoscopic contexts include both <EM>left</EM> and <EM>right</EM> buffers.
Likewise, single-buffered contexts include only <EM>front</EM>
buffers, and double-buffered contexts include both <EM>front</EM> and
<EM>back</EM> buffers. The context is selected at GL initialization.
<STRONG>NOTES</STRONG>
It is always the case that <STRONG>GL_AUX</STRONG>i = <STRONG>GL_AUX0</STRONG> + i.
<STRONG>ERRORS</STRONG>
<STRONG>GL_INVALID_ENUM</STRONG> is generated if <EM>mode</EM> is not an accepted
value.
<STRONG>GL_INVALID_OPERATION</STRONG> is generated if none of the buffers
indicated by <EM>mode</EM> exists.
<STRONG>GL_INVALID_OPERATION</STRONG> is generated if <STRONG>glDrawBuffer</STRONG> is
executed between the execution of <STRONG>glBegin</STRONG> and the
corresponding execution of <STRONG>glEnd</STRONG>.
<STRONG>ASSOCIATED</STRONG> <STRONG>GETS</STRONG>
<STRONG>glGet</STRONG> with argument <STRONG>GL_DRAW_BUFFER</STRONG>
<STRONG>glGet</STRONG> with argument <STRONG>GL_AUX_BUFFERS</STRONG>
<STRONG>SEE</STRONG> <STRONG>ALSO</STRONG>
<STRONG>glBlendFunc</STRONG>, <STRONG>glColorMask</STRONG>, <STRONG>glIndexMask</STRONG>, <STRONG>glLogicOp</STRONG>,
<STRONG>glReadBuffer</STRONG>
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