OpenGL man pages
gluTessVertex.3gl (GLU versions 1.0 and 1.1)
gluTessVertex - specify a vertex on a polygon
void gluTessVertex( GLUtriangulatorObj *tobj,
void *data )
tobj Specifies the tessellation object (created with gluNewTess).
v Specifies the location of the vertex.
data Specifies an opaque pointer passed back to the user with the vertex
callback (as specified by gluTessCallback).
gluTessVertex describes a vertex on a polygon that the user is defining.
Successive gluTessVertex calls describe a closed contour. For example, if
the user wants to describe a quadrilateral, then gluTessVertex should be
called four times. gluTessVertex can only be called between
gluBeginPolygon and gluEndPolygon.
data normally points to a structure containing the vertex location, as well
as other per-vertex attributes such as color and normal. This pointer is
passed back to the user through the GLU_VERTEX callback after tessellation
(see the gluTessCallback reference page).
A quadrilateral with a triangular hole in it can be described as follows:
gluTessVertex(tobj, v1, v1);
gluTessVertex(tobj, v2, v2);
gluTessVertex(tobj, v3, v3);
gluTessVertex(tobj, v4, v4);
gluTessVertex(tobj, v5, v5);
gluTessVertex(tobj, v6, v6);
gluTessVertex(tobj, v7, v7);
gluBeginPolygon, gluNewTess, gluNextContour, gluTessCallback