Shading By Fast Bi-Quadratic Normal Vector Interpolation

The use of Bezier curves and Bezier triangles has been extensively explored in the field of computer graphics. The purpose of this paper is to show that Bezier triangles and curves can be used for reducing the cost of Biquadratic Phong shading. A shading algorithm has been proposed which uses quadratic Bezier triangle’s blending functions for performing quadratic interpolation of normal vector along the edges of a polygon and quadratic Bezier curve for interpolation of normal vector along the scan line. The visual results of this algorithm are exactly the same as that of Bi-quadratic Phong shading. By virtue of fast calculation of area coordinates at the edge points, this shading algorithm becomes faster than all the known fast Bi-quadratic normal vector interpolation methods, which attain the same visual quality as that of Biquadratic Phong shading. This paper summarizes and compares the proposed method with the other existing faster methods. Flexibility of the proposed method has been utilized to further reduce the cost of Bi-quadratic Phong shading by incorporating another fast angular interpolation method along the scan line.