Patent ID: 7190374

Claim:
A method of shading a polygon having different shadings that correspond to regions of a model having the different shadings, the polygon defining a border between the regions, the method comprising: identifying points on edges of the polygon using shading values for vertices of the polygon, one of the vertices belonging to one of the regions and another of the vertices belonging to a different one of the regions, the points corresponding to boundaries between the regions having the different shadings; connecting the points to each other across the polygon to form at least two areas within the polygon, the areas corresponding to the regions having different shadings; at least one area of the at least two area having a number of edges that is different from a number of edges in the polygon; tessellating the at least one area to produce sub-polygons having a same number of edges as the number of edges in the polygon; and shading the at least two areas differently so that each of the at least two areas has a same shading as its corresponding region.