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'\" te
'\"! tbl|eqn | mmdoc
'\"macro stdmacro
.ds Vn Version 1.2
.ds Dt 24 September 1999
.ds Re Release 1.2.1
.ds Dp Jan 14 18:30
.ds Dm 01 clear.gl
.ds Xs 16977 5 clear.gl
.TH GLCLEAR 3G
.SH NAME
.B "glClear
\- clear buffers to preset values
.SH C SPECIFICATION
void \f3glClear\fP(
GLbitfield \fImask\fP )
.nf
.fi
.SH PARAMETERS
.TP \w'\f2mask\fP\ \ 'u
\f2mask\fP
Bitwise OR of masks that indicate the buffers to be cleared.
The four masks are
\%\f3GL_COLOR_BUFFER_BIT\fP,
\%\f3GL_DEPTH_BUFFER_BIT\fP,
\%\f3GL_ACCUM_BUFFER_BIT\fP, and
\%\f3GL_STENCIL_BUFFER_BIT\fP.
.SH DESCRIPTION
\%\f3glClear\fP sets the bitplane area of the window to values previously selected
by \%\f3glClearColor\fP, \%\f3glClearIndex\fP, \%\f3glClearDepth\fP,
\%\f3glClearStencil\fP, and \%\f3glClearAccum\fP.
Multiple color buffers can be cleared simultaneously by selecting
more than one buffer at a time using \%\f3glDrawBuffer\fP.
.P
The pixel ownership test,
the scissor test,
dithering, and the buffer writemasks affect the operation of \%\f3glClear\fP.
The scissor box bounds the cleared region.
Alpha function,
blend function,
logical operation,
stenciling,
texture mapping,
and depth-buffering are ignored by \%\f3glClear\fP.
.P
\%\f3glClear\fP takes a single argument that is the bitwise OR of several
values indicating which buffer is to be cleared.
.P
The values are as follows:
.TP 28
\%\f3GL_COLOR_BUFFER_BIT\fP
Indicates the buffers currently enabled for color
writing.
.TP
\%\f3GL_DEPTH_BUFFER_BIT\fP
Indicates the depth buffer.
.TP
\%\f3GL_ACCUM_BUFFER_BIT\fP
Indicates the accumulation buffer.
.TP
\%\f3GL_STENCIL_BUFFER_BIT\fP
Indicates the stencil buffer.
.P
The value to which each buffer is cleared depends on the setting of the
clear value for that buffer.
.SH NOTES
If a buffer is not present,
then a \%\f3glClear\fP directed at that buffer has no effect.
.SH ERRORS
\%\f3GL_INVALID_VALUE\fP is generated if any bit other than the four defined
bits is set in \f2mask\fP.
.P
\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glClear\fP
is executed between the execution of \%\f3glBegin\fP
and the corresponding execution of \%\f3glEnd\fP.
.SH ASSOCIATED GETS
\%\f3glGet\fP with argument \%\f3GL_ACCUM_CLEAR_VALUE\fP
.br
\%\f3glGet\fP with argument \%\f3GL_DEPTH_CLEAR_VALUE\fP
.br
\%\f3glGet\fP with argument \%\f3GL_INDEX_CLEAR_VALUE\fP
.br
\%\f3glGet\fP with argument \%\f3GL_COLOR_CLEAR_VALUE\fP
.br
\%\f3glGet\fP with argument \%\f3GL_STENCIL_CLEAR_VALUE\fP
.SH SEE ALSO
\%\f3glClearAccum(3G)\fP,
\%\f3glClearColor(3G)\fP,
\%\f3glClearDepth(3G)\fP,
\%\f3glClearIndex(3G)\fP,
\%\f3glClearStencil(3G)\fP,
\%\f3glColorMask(3G)\fP,
\%\f3glDepthMask(3G)\fP,
\%\f3glDrawBuffer(3G)\fP,
\%\f3glScissor(3G)\fP,
\%\f3glStencilMask(3G)\fP
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