glClear(3G) OpenGL Reference glClear(3G)
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 GLCOLORBUFFERBIT, GLDEPTHBUFFERBIT,
GLACCUMBUFFERBIT, and GLSTENCILBUFFERBIT.
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 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:
GLCOLORBUFFERBIT Indicates the buffers currently enabled for
color writing.
GLDEPTHBUFFERBIT Indicates the depth buffer.
GLACCUMBUFFERBIT Indicates the accumulation buffer.
GLSTENCILBUFFERBIT 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
GLINVALIDVALUE is generated if any bit other than the four defined bits
is set in mask.
GLINVALIDOPERATION is generated if glClear is executed between the
execution of glBegin and the corresponding execution of glEnd.
Page 1
glClear(3G) OpenGL Reference glClear(3G)
ASSOCIATED GETS
glGet with argument GLACCUMCLEARVALUE
glGet with argument GLDEPTHCLEARVALUE
glGet with argument GLINDEXCLEARVALUE
glGet with argument GLCOLORCLEARVALUE
glGet with argument GLSTENCILCLEARVALUE
SEE ALSO
glClearAccum, glClearColor, glClearDepth, glClearIndex, glClearStencil,
glDrawBuffer, glScissor
Page 2