Documentation de Gambas - /comp/gb.opengl.glsl/gl/drawbuffer

/comp/gb.opengl.glsl/gl/drawbuffer

# Gl.DrawBuffer (gb.opengl)

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.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 Gl.DrawBuffer. 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.

### Associated Gets

Gl.Get with argument Gl.DRAW_BUFFER

### See also

- Gl.BlendFunc,

- Gl.ColorMask,

Gl.DrawBuffers, Gl.LogicOp, Gl.ReadBuffer

See original documentation on OpenGL website