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glClear - clear buffers to preset values
void glClear(
GLbitfield mask )
- mask
- Bitwise OR of masks that indicate the buffers to be cleared.
The four masks are GL_COLOR_BUFFER_BIT, GL_DEPTH_BUFFER_BIT, GL_ACCUM_BUFFER_BIT,
and GL_STENCIL_BUFFER_BIT.
glClear sets the bitplane area of
the window to values previously selected by glClearColor, glClearIndex,
glClearDepth, glClearStencil, and glClearAccum. Multiple color buffers
can be cleared simultaneously by selecting more than one buffer at a time
using glDrawBuffer.
The pixel ownership test, the scissor test, dithering,
and the buffer writemasks affect the operation of glClear. The scissor box
bounds the cleared region. Alpha function, blend function, logical operation,
stenciling, texture mapping, and depth-buffering are ignored by glClear.
glClear 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_ACCUM_BUFFER_BIT
- Indicates the accumulation
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.
If a buffer is not present, then a glClear directed
at that buffer has no effect.
GL_INVALID_VALUE is generated if any
bit other than the four defined bits is set in mask.
GL_INVALID_OPERATION
is generated if glClear is executed between the execution of glBegin and
the corresponding execution of glEnd.
glGet with argument
GL_ACCUM_CLEAR_VALUE
glGet with argument GL_DEPTH_CLEAR_VALUE
glGet with argument GL_INDEX_CLEAR_VALUE
glGet with argument GL_COLOR_CLEAR_VALUE
glGet with argument GL_STENCIL_CLEAR_VALUE
glClearAccum(3G)
, glClearColor(3G)
,
glClearDepth(3G)
, glClearIndex(3G)
, glClearStencil(3G)
, glColorMask(3G)
,
glDepthMask(3G)
, glDrawBuffer(3G)
, glScissor(3G)
, glStencilMask(3G)
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