Shading circuit for shading a plurality of polygons which constitute a solid model, and method of shading the same

摘要

A shading circuit has a unit for calculating coor­dinates and intensities of points inside a polygon based on X, Y, and Z coordinates and intensities of vertexes of each of polygons constituting a solid model. This unit includes a preprocessing section (l5) for obtaining the depth change ΔZ/ΔX of Z coordinate for each unit change in X coordinate and the change ΔI/ΔX of intensity for each unit change in X coordinate, based on X, Y, and Z coordinates and intensities of three vertexes of each of triangular polygons constituting a solid model, and a digital differential analyzer unit (l6) for obtaining Z coordinates and intensities of points inside each poly­gon commonly using ΔZ/ΔX and ΔI/ΔX when the X and Y coordinates of the points are determined.