gluNextContour(3)

NAME

       gluNextContour - mark the beginning of another contour

C SPECIFICATION

       void gluNextContour( GLUtesselator* tess,
                            GLenum type )

       delim $$

PARAMETERS

       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

       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  con-
                         sidered  to  be exterior. All other contours are con-
                         sidered 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.

       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       This command is obsolete and is  provided  for  backward  compatibility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

       A quadrilateral with a triangular hole in it can be described  as  fol-
       lows:

       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

       gluBeginPolygon(3G),        gluNewTess(3G),        gluTessCallback(3G),
       gluTessVertex(3G), gluTessBeginContour(3G)

                                                            GLUNEXTCONTOUR(3G)