gluTessVertex

NAME

gluTessVertex -- specify a vertex on a polygon

C SPECIFICATION

void gluTessVertex(GLUtriangulatorObj *tobj,

GLdouble v[3],

void *data)

PARAMETERS

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).

DESCRIPTION

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 gluTessCallback).

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);