CONVEXITY THEOREM OF PARAMETRIC TRIANGULAR BEZIER SURFACES

The author introduces twist vectors of control nets of parametric triangular Bezier surfaces, With twist vectors and other geomtric magnitudes a sufficient condition for parametric triangular Bezier surfaces to be convex is offered. Incidently a necessary and sufficient condition for triangular Bezier surfaces of parametric form to degenerate to that of functional form is given. A less stringent sufficient condition is proposed for quadratic.Bezier surfaces to be convex.