GLUNEXTCONTOUR(3G)GLUNEXTCONTOUR(3G)NAMEgluNextContour - 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.
DESCRIPTIONgluNextContour 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.
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This command is obsolete and is provided for backward compatibility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
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 ALSOgluBeginPolygon(3G), gluNewTess(3G), gluTessCallback(3G),
gluTessVertex(3G), gluTessBeginContour(3G)
March 1, 2011
