1GLUNEXTCONTOUR(3G)               OpenGL Manual              GLUNEXTCONTOUR(3G)
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NAME

6       gluNextContour - mark the beginning of another contour
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C SPECIFICATION

9       void gluNextContour(GLUtesselator* tess, GLenum type);
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PARAMETERS

12       tess
13           Specifies the tessellation object (created with gluNewTess()).
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15       type
16           Specifies the type of the contour being defined. Valid values are
17           GLU_EXTERIOR, GLU_INTERIOR, GLU_UNKNOWN, GLU_CCW, and GLU_CW.
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DESCRIPTION

20       gluNextContour is used in describing polygons with multiple contours.
21       After the first contour has been described through a series of
22       gluTessVertex() calls, a gluNextContour call indicates that the
23       previous contour is complete and that the next contour is about to
24       begin. Another series of gluTessVertex() calls is then used to describe
25       the new contour. This process can be repeated until all contours have
26       been described.
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28       type defines what type of contour follows. The legal contour types are
29       as follows:
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31       GLU_EXTERIOR
32           An exterior contour defines an exterior boundary of the polygon.
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34       GLU_INTERIOR
35           An interior contour defines an interior boundary of the polygon
36           (such as a hole).
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38       GLU_UNKNOWN
39           An unknown contour is analyzed by the library to determine if it is
40           interior or exterior.
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42       GLU_CCW,
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44       GLU_CW
45           The first GLU_CCW or GLU_CW contour defined is considered to be
46           exterior. All other contours are considered to be exterior if they
47           are oriented in the same direction (clockwise or counterclockwise)
48           as the first contour, and interior if they are not.
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50       If one contour is of type GLU_CCW or GLU_CW, then all contours must be
51       of the same type (if they are not, then all GLU_CCW and GLU_CW contours
52       will be changed to GLU_UNKNOWN).
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54       Note that there is no real difference between the GLU_CCW and GLU_CW
55       contour types.
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57       Before the first contour is described, gluNextContour can be called to
58       define the type of the first contour. If gluNextContour is not called
59       before the first contour, then the first contour is marked
60       GLU_EXTERIOR.
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62       This command is obsolete and is provided for backward compatibility
63       only. Calls to gluNextContour are mapped to gluTessEndContour()
64       followed by gluTessBeginContour().
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EXAMPLE

67       A quadrilateral with a triangular hole in it can be described as
68       follows:
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70           gluBeginPolygon(tobj);
71              gluTessVertex(tobj, v1, v1);
72              gluTessVertex(tobj, v2, v2);
73              gluTessVertex(tobj, v3, v3);
74              gluTessVertex(tobj, v4, v4);
75           gluNextContour(tobj, GLU_INTERIOR);
76              gluTessVertex(tobj, v5, v5);
77              gluTessVertex(tobj, v6, v6);
78              gluTessVertex(tobj, v7, v7);
79           gluEndPolygon(tobj);
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SEE ALSO

84       gluBeginPolygon(), gluNewTess(), gluTessBeginContour(),
85       gluTessCallback(), gluTessVertex()
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88       Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed
89       under the SGI Free Software B License. For details, see
90       http://oss.sgi.com/projects/FreeB/.
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AUTHORS

93       opengl.org
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97opengl.org                        06/10/2014                GLUNEXTCONTOUR(3G)
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