/ comp / gb.opengl / gl / drawbuffer
Gl.DrawBuffer (gb.opengl)
Syntax

    STATIC SUB DrawBuffer ( Mode AS Integer )

### Specify which color buffers are to be drawn into

#### Parameters

- Mode specifies up to four color buffers to be drawn into. Symbolic constants Gl.GL_NONE, Gl.GL_FRONT_LEFT, Gl.GL_FRONT_RIGHT, Gl.GL_BACK_LEFT, Gl.GL_BACK_RIGHT, Gl.GL_FRONT, Gl.GL_BACK, Gl.GL_LEFT, Gl.GL_RIGHT, Gl.GL_FRONT_AND_BACK, and Gl.GL_AUXi, where i is between 0 and Gl.GL_AUX_BUFFERS - 1, are accepted. The default value is Gl.GL_FRONT for single buffered contexts, and Gl.GL_BACK for double-buffered contexts.

#### Description

When colors are written to the frame buffer, they are written into the color buffers specified by

- Gl.GL_NONE no color buffers are written.

- Gl.GL_FRONT_LEFT only the front left color buffer is written.

- Gl.GL_FRONT_RIGHT only the front right color buffer is written.

- Gl.GL_BACK_LEFT only the back left color buffer is written.

- Gl.GL_BACK_RIGHT only the back right color buffer is written.

- Gl.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.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.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.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.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.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.

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

#### Errors

Gl.GL_INVALID_ENUM is generated if mode is not an accepted value.
Gl.GL_INVALID_OPERATION is generated if none of the buffers indicated by mode exists.
Gl.GL_INVALID_OPERATION is generated if Gl.DrawBuffer is called between a call to Gl.Begin and the corresponding call to Gl.End.

#### Associated Gets

Gl.GetDrawBuffer
Gl.GetAuxBuffers

### See also

Gl.BlendFunc , Gl.ColorMask , Gl.IndexMask, Gl.LogicOp, Gl.ReadSource