glClear
[New
- Windows 95, OEM Service Release 2]
The glClear
function clears buffers within the viewport.
void glClear(
|
GLbitfield mask |
|
|
); |
|
Parameters
mask
Bitwise OR of
masks that indicate the buffers to be cleared. The four masks are as follows.
|
Mask |
Buffer
to be Cleared |
|
GL_COLOR_BUFFER_BIT |
The buffers
currently enabled for color writing. |
|
GL_DEPTH_BUFFER_BIT |
The depth
buffer. |
|
GL_ACCUM_BUFFER_BIT |
The
accumulation buffer. |
|
GL_STENCIL_BUFFER_BIT |
The stencil
buffer. |
Remarks
The glClear
function sets the bitplane area of the window to values previously selected by glClearColor, glClearIndex, glClearDepth, glClearStencil, and glClearAccum. You can clear multiple
color buffers 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.
The alpha function, blend function, logical operation, stenciling, texture
mapping, and z-buffering are ignored by glClear.
The glClear
function takes a single argument (mask) that is the bitwise OR of
several values indicating which buffer is to be cleared.
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, a glClear call directed at that buffer has no effect.
The following
functions retrieve information related to glClear:
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
Error Codes
The following
are the error codes generated and their conditions.
|
Error
Code |
Condition |
|
GL_INVALID_VALUE
|
Any bit
other than the four defined bits was set in mask. |
|
GL_INVALID_OPERATION
|
glClear was called between a call to glBegin and the
corresponding call to glEnd. |
See Also