Patent ID: 6741247
Filing Date: 2004-05-25
Classification: G06T

Abstract:
A method for shading a 3-dimensional computer generated image that comprises a set of pixels, said method including the steps of:representing each object in the image as a set of flat polygons, each polygon being a surface defined by a set of vertices and being in a defined orientation relative to an image plane; for each polygon, supplying vertex data that define the location of the vertices of the polygon in the image and that define the orientation of the surface of the polygon relative to the image plane; for each polygon, generating edge surface-defining data based on the vertex data that define a plurality of edge surfaces for the polygon, each edge surface separating the image into a region potentially inside the polygon surface and a region that is outside of the polygon surface, each edge surface being a flat surface that extends perpendicularly to the image plane; for each pixel over which the polygon surface may extend, deriving a depth value for the polygon surface at the pixel based on the data defining the orientation of the polygon surface; for each pixel over which the polygon surface may extend, determining if the pixel is inside the image regions in which the polygon surface is potentially present as defined by the edge surfaces of the polygon based on the edge surface-defining data for the polygon; and, if, as a result of said determining step, it is determined that the pixel is inside the image regions defined by each of the edge surfaces of the polygon in which the polygon surface is potentially present, storing the depth value of the polygon surface at the pixel for subsequent processing.