Patent ID: 6175367
Filing Date: 2001-01-16
Classification: G06T

Abstract:
In a graphics system, a method for shading an image comprised of polygons, said method comprising the steps of:selecting a polygon of the image having vertices, each vertex having an x, y, and z coordinates, a normalized surface normal vector (N), a normalized half-angle vector (H), and a specular exponent (s);computing a set of first difference terms between N and H for each of the vertices, one first difference term for each vertex;computing a specular term according to a function: s*(.vertline.N-H.vertline.)/2;selecting a pixel in the polygon;calculating an index term corresponding to the pixel by interpolating a plurality of y terms;storing a Gaussian look-up table in a memory unit coupled to the graphics system;obtaining a specular term for the pixel by applying the index term to the Gaussian look-up table;determining a color for the pixel by incorporating the specular term according to a lighting equation.