74 lines
2.4 KiB
Plaintext
74 lines
2.4 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 6 March 1997
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.ds Re Release 1.2.0
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.ds Dp May 02 11:53
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.ds Dm 37 tessbegin
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.ds Xs 55678 4 tessbeginpolygon.gl
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.TH GLUTESSBEGINPOLYGON 3G
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.SH NAME
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.B "gluTessBeginPolygon
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\- delimit a polygon description
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.SH C SPECIFICATION
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void \f3gluTessBeginPolygon\fP(
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GLUtesselator* \fItess\fP,
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.nf
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.ta \w'\f3void \fPgluTessBeginPolygon( 'u
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GLvoid* \fIdata\fP )
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.fi
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.EQ
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delim $$
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.EN
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.SH PARAMETERS
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.TP \w'\f2tess\fP\ \ 'u
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\f2tess\fP
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Specifies the tessellation object (created with \%\f3gluNewTess\fP).
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.TP
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\f2data\fP
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Specifies a pointer to user polygon data.
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.SH DESCRIPTION
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\%\f3gluTessBeginPolygon\fP and \%\f3gluTessEndPolygon\fP delimit the definition of a
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convex, concave or self-intersecting polygon. Within each \%\f3gluTessBeginPolygon\fP/\%\f3gluTessEndPolygon\fP
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pair, there must be one or more calls to \%\f3gluTessBeginContour\fP/\%\f3gluTessEndContour\fP.
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Within each contour, there are zero or more calls to \%\f3gluTessVertex\fP. The vertices
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specify a closed contour (the last vertex of each contour is automatically linked
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to the first). See the \%\f3gluTessVertex\fP, \%\f3gluTessBeginContour\fP, and
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\%\f3gluTessEndContour\fP reference pages for more details.
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.P
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\f2data\fP is a pointer to a user-defined data structure. If the appropriate callback(s)
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are specified (see \%\f3gluTessCallback\fP), then this pointer is returned to the
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callback function(s). Thus, it is a convenient way to store per-polygon information.
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.P
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Once \%\f3gluTessEndPolygon\fP is called, the polygon is tessellated, and the
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resulting triangles are described through callbacks.
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See \%\f3gluTessCallback\fP for descriptions of the callback functions.
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.SH EXAMPLE
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A quadrilateral with a triangular hole in it can be described as follows:
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.sp
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.Ex
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gluTessBeginPolygon(tobj, NULL);
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gluTessBeginContour(tobj);
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gluTessVertex(tobj, v1, v1);
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gluTessVertex(tobj, v2, v2);
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gluTessVertex(tobj, v3, v3);
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gluTessVertex(tobj, v4, v4);
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gluTessEndContour(tobj);
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.bp
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gluTessBeginContour(tobj);
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gluTessVertex(tobj, v5, v5);
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gluTessVertex(tobj, v6, v6);
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gluTessVertex(tobj, v7, v7);
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gluTessEndContour(tobj);
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gluTessEndPolygon(tobj);
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.Ee
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.sp
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.SH SEE ALSO
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\%\f3gluNewTess(3G)\fP, \%\f3gluTessBeginContour(3G)\fP, \%\f3gluTessVertex(3G)\fP,
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\%\f3gluTessCallback(3G)\fP,
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\%\f3gluTessProperty(3G)\fP, \%\f3gluTessNormal(3G)\fP,
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\%\f3gluTessEndPolygon(3G)\fP
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