Gl.Clear (gb.opengl)
Static Sub Clear ( Mask As Integer )
Clear buffers to preset values.
Parameters
- mask
-
Bitwise OR of masks that indicate the buffers to be cleared.
The three masks are
Gl.COLOR_BUFFER_BIT,
Gl.DEPTH_BUFFER_BIT, and
Gl.STENCIL_BUFFER_BIT.
Description
Gl.Clear sets the bitplane area of the window to values previously selected
by
Gl.ClearColor,
Gl.ClearDepth, and
Gl.ClearStencil.
Multiple color buffers can be cleared simultaneously by selecting
more than one buffer at a time using
Gl.DrawBuffer.
The pixel ownership test,
the scissor test,
dithering, and the buffer writemasks affect the operation of
Gl.Clear.
The scissor box bounds the cleared region.
Alpha function,
blend function,
logical operation,
stenciling,
texture mapping,
and depth-buffering are ignored by
Gl.Clear.
Gl.Clear takes a single argument that is the bitwise
OR of several
values indicating which buffer is to be cleared.
The values are as follows:
- Gl.COLOR_BUFFER_BIT
-
Indicates the buffers currently enabled for color
writing.
- Gl.DEPTH_BUFFER_BIT
-
Indicates the depth buffer.
- Gl.STENCIL_BUFFER_BIT
-
Indicates the stencil buffer.
The value to which each buffer is cleared depends on the setting of the
clear value for that buffer.
Notes
If a buffer is not present,
then a
Gl.Clear directed at that buffer has no effect.
Errors
Gl.INVALID_VALUE is generated if any bit other than the three defined
bits is set in
mask.
Associated Gets
Gl.Get with argument Gl.DEPTH_CLEAR_VALUE
Gl.Get with argument Gl.COLOR_CLEAR_VALUE
Gl.Get with argument Gl.STENCIL_CLEAR_VALUE
See Also
Gl.ClearColor,
Gl.ClearDepth,
Gl.ClearStencil,
Gl.ColorMask,
Gl.DepthMask,
Gl.DrawBuffer,
Gl.Scissor,
Gl.StencilMask
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB.
➡ See original documentation