gluTessCallback(i->tesselator, GLU_TESS_VERTEX, (callbackfunction_t)vertexCallback);
gluTessCallback(i->tesselator, GLU_TESS_BEGIN, (callbackfunction_t)beginCallback);
gluTessCallback(i->tesselator, GLU_TESS_END, (callbackfunction_t)endCallback);
gluTessCallback(i->tesselator, GLU_TESS_VERTEX, (callbackfunction_t)vertexCallback);
gluTessCallback(i->tesselator, GLU_TESS_BEGIN, (callbackfunction_t)beginCallback);
gluTessCallback(i->tesselator, GLU_TESS_END, (callbackfunction_t)endCallback);