70 lines
2.0 KiB
Plaintext
70 lines
2.0 KiB
Plaintext
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'\" e
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'\"! 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 scissor.g
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.ds Xs 30565 4 scissor.gl
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.TH GLSCISSOR 3G
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.SH NAME
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.B "glScissor
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\- define the scissor box
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.SH C SPECIFICATION
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void \f3glScissor\fP(
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GLint \fIx\fP,
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.nf
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.ta \w'\f3void \fPglScissor( 'u
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GLint \fIy\fP,
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GLsizei \fIwidth\fP,
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GLsizei \fIheight\fP )
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.fi
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.SH PARAMETERS
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.TP \w'\f2x\fP\ \f2y\fP\ \ 'u
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\f2x\fP, \f2y\fP
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Specify the lower left corner of the scissor box.
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Initially (0, 0).
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.TP
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\f2width\fP, \f2height\fP
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Specify the width and height of the scissor box.
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When a GL context is first attached to a window,
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\f2width\fP and \f2height\fP are set to the dimensions of that window.
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.SH DESCRIPTION
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\%\f3glScissor\fP defines a rectangle, called the scissor box,
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in window coordinates.
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The first two arguments,
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\f2x\fP and \f2y\fP,
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specify the lower left corner of the box.
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\f2width\fP and \f2height\fP specify the width and height of the box.
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.P
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To enable and disable the scissor test, call
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\%\f3glEnable\fP and \%\f3glDisable\fP with argument
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\%\f3GL_SCISSOR_TEST\fP. The test is initially disabled.
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While the test is enabled, only pixels that lie within the scissor box
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can be modified by drawing commands.
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Window coordinates have integer values at the shared corners of
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frame buffer pixels.
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\f7glScissor(0,0,1,1)\fP allows modification of only the lower left
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pixel in the window, and \f7glScissor(0,0,0,0)\fP doesn't allow
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modification of any pixels in the window.
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.P
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When the scissor test is disabled,
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it is as though the scissor box includes the entire window.
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.SH ERRORS
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\%\f3GL_INVALID_VALUE\fP is generated if either \f2width\fP or \f2height\fP is negative.
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.P
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\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glScissor\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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.bp
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.SH ASSOCIATED GETS
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\%\f3glGet\fP with argument \%\f3GL_SCISSOR_BOX\fP
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.br
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\%\f3glIsEnabled\fP with argument \%\f3GL_SCISSOR_TEST\fP
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.SH SEE ALSO
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\%\f3glEnable(3G)\fP,
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\%\f3glViewport(3G)\fP
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