GLCLEAR() MachTen Programmer’s Manual GLCLEAR()

NAME
glClear - clear buffers to preset values

C SPECIFICATION
void glClear( GLbitfield mask )

PARAMETERS
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.

DESCRIPTION
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 func-
tion, blend function, logical operation, stenciling, tex-
ture 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.

NOTES
If a buffer is not present, then a glClear directed at
that buffer has no effect.

ERRORS
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.

ASSOCIATED GETS
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

SEE ALSO
glClearAccum, glClearColor, glClearDepth, glClearIndex,
glClearStencil, glDrawBuffer, glScissor

MachTen 2