103 lines
3.1 KiB
Plaintext
103 lines
3.1 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 nextconto
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.ds Xs 37451 5 nextcontour.gl
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.TH GLUNEXTCONTOUR 3G
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.SH NAME
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.B "gluNextContour
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\- mark the beginning of another contour
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.SH C SPECIFICATION
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void \f3gluNextContour\fP(
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GLUtesselator* \fItess\fP,
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.nf
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.ta \w'\f3void \fPgluNextContour( 'u
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GLenum \fItype\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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\f2type\fP
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Specifies the type of the contour being defined. Valid values are
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\%\f3GLU_EXTERIOR\fP,
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\%\f3GLU_INTERIOR\fP,
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\%\f3GLU_UNKNOWN\fP,
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\%\f3GLU_CCW\fP, and
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\%\f3GLU_CW\fP.
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.SH DESCRIPTION
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\%\f3gluNextContour\fP is used in describing polygons with multiple contours. After the first
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contour has been described through a series of \%\f3gluTessVertex\fP calls,
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a \%\f3gluNextContour\fP call indicates that the previous contour is complete and that the
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next contour is about to begin.
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Another series of \%\f3gluTessVertex\fP calls is then used to describe the new
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contour. This process can be repeated until all contours have been described.
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.P
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\f2type\fP defines what type of contour follows.
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The legal contour types are as follows:
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.TP 18
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\%\f3GLU_EXTERIOR\fP
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An exterior contour defines an exterior boundary of the polygon.
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.TP
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\%\f3GLU_INTERIOR\fP
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An interior contour defines an interior boundary of the polygon (such as
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a hole).
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.TP
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\%\f3GLU_UNKNOWN\fP
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An unknown contour is analyzed by the library to determine if it is interior
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or exterior.
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.TP
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\%\f3GLU_CCW\fP,
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.TP
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\%\f3GLU_CW\fP
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The first \%\f3GLU_CCW\fP or \%\f3GLU_CW\fP contour defined is considered to
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be exterior. All other contours are considered to be exterior if they
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are oriented in the same direction (clockwise or counterclockwise) as
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the first contour, and interior if they are not.
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.P
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If one contour is of type \%\f3GLU_CCW\fP or \%\f3GLU_CW\fP, then all
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contours must be of the same type (if they are not, then all \%\f3GLU_CCW\fP
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and \%\f3GLU_CW\fP contours will be changed to \%\f3GLU_UNKNOWN\fP).
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.P
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Note that there is no real difference between the \%\f3GLU_CCW\fP and
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\%\f3GLU_CW\fP contour types.
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.P
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Before the first contour is described, \%\f3gluNextContour\fP can be called to
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define the type of the first contour.
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If \%\f3gluNextContour\fP is not called before the first contour, then the first contour is
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marked \%\f3GLU_EXTERIOR\fP.
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.P
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This command is obsolete and is provided for backward compatibility
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only. Calls to \%\f3gluNextContour\fP are mapped to \%\f3gluTessEndContour\fP
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followed by
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\%\f3gluTessBeginContour\fP.
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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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gluBeginPolygon(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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gluNextContour(tobj, GLU_INTERIOR);
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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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gluEndPolygon(tobj);
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.Ee
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.SH SEE ALSO
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\%\f3gluBeginPolygon(3G)\fP, \%\f3gluNewTess(3G)\fP, \%\f3gluTessCallback(3G)\fP, \%\f3gluTessVertex(3G)\fP,
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\%\f3gluTessBeginContour(3G)\fP
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