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