GlDrawBuffer
_glDrawBuffer: specify which color buffers are to be drawn into
Contents
Syntax
- SUB _glDrawBuffer (BYVAL mode AS _UNSIGNED LONG)
- void _glDrawBuffer(GLenum mode);
- 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, and _GL_FRONT_AND_BACK are accepted. 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.
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.
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.
Use With:
_glGet with argument _GL_DRAW_BUFFER
See also
SUB _GL _glBindFramebuffer, _glBlendFunc, _glColorMask, _glDrawBuffers, _glLogicOp
