gluNextContour(3G)	       OpenGL Reference		    gluNextContour(3G)

NAME    [Toc]    [Back]

     gluNextContour - mark the beginning of another contour

C SPECIFICATION    [Toc]    [Back]

     void gluNextContour( GLUtesselator* tess,
			  GLenum type )

PARAMETERS    [Toc]    [Back]

     tess  Specifies the tessellation object (created with gluNewTess).

     type  Specifies the type of the contour being defined. Valid values are
	   GLU_EXTERIOR, GLU_INTERIOR, GLU_UNKNOWN, GLU_CCW, and GLU_CW.

DESCRIPTION    [Toc]    [Back]

     gluNextContour is used in describing polygons with	multiple contours.
     After the first contour has been described	through	a series of
     gluTessVertex calls, a gluNextContour call	indicates that the previous
     contour is	complete and that the next contour is about to begin.  Another
     series of gluTessVertex calls is then used	to describe the	new contour.
     This process can be repeated until	all contours have been described.

     type defines what type of contour follows.	 The legal contour types are
     as	follows:

     GLU_EXTERIOR      An exterior contour defines an exterior boundary	of the
		       polygon.

     GLU_INTERIOR      An interior contour defines an interior boundary	of the
		       polygon (such as	a hole).

     GLU_UNKNOWN       An unknown contour is analyzed by the library to
		       determine if it is interior or exterior.

     GLU_CCW,

     GLU_CW	       The first GLU_CCW or GLU_CW contour defined is
		       considered to be	exterior. All other contours are
		       considered to be	exterior if they are oriented in the
		       same direction (clockwise or counterclockwise) as the
		       first contour, and interior if they are not.

     If	one contour is of type GLU_CCW or GLU_CW, then all contours must be of
     the same type (if they are	not, then all GLU_CCW and GLU_CW contours will
     be	changed	to GLU_UNKNOWN).

     Note that there is	no real	difference between the GLU_CCW and GLU_CW
     contour types.






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gluNextContour(3G)	       OpenGL Reference		    gluNextContour(3G)



     Before the	first contour is described, gluNextContour can be called to
     define the	type of	the first contour.  If gluNextContour is not called
     before the	first contour, then the	first contour is marked	GLU_EXTERIOR.

     This command is obsolete and is provided for backward compatibility only.
     Calls to gluNextContour are mapped	to gluTessEndContour followed by
     gluTessBeginContour.

EXAMPLE    [Toc]    [Back]

     A quadrilateral with a triangular hole in it can be described as follows:


	  gluBeginPolygon(tobj);
	     gluTessVertex(tobj, v1, v1);
	     gluTessVertex(tobj, v2, v2);
	     gluTessVertex(tobj, v3, v3);
	     gluTessVertex(tobj, v4, v4);
	  gluNextContour(tobj, GLU_INTERIOR);
	     gluTessVertex(tobj, v5, v5);
	     gluTessVertex(tobj, v6, v6);
	     gluTessVertex(tobj, v7, v7);
	  gluEndPolygon(tobj);

SEE ALSO    [Toc]    [Back]

     gluBeginPolygon, gluNewTess, gluTessCallback, gluTessVertex,
     gluTessBeginContour


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