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_BITIndicates the buffers currently enabled for color writing.
GL_DEPTH_BUFFER_BITIndicates the depth buffer.
GL_ACCUM_BUFFER_BITIndicates the accumulation buffer.
GL_STENCIL_BUFFER_BITIndicates the stencil buffer.
The value to which each buffer is cleared depends on the setting of the clear value for that buffer.
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,
glClearColor,
glClearDepth,
glClearIndex,
glClearStencil,
glColorMask,
glDepthMask,
glDrawBuffer,
glScissor,
glStencilMask
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