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.