Patent ID: 6184887
Filing Date: 2001-02-06
Classification: G06T

Abstract:
In gradient computation hardware having a memory for storing a plurality of image variables, each image variable being assocaited with a predetermined number of bits capable of representing data within a dynamic range, a method of clamping, by the gradient computation hardware, gradients in a computer graphics image, the method comprising steps of:computing, by the gradient computation hardware, the area of a polygon comprising a plurality of vectors, the polygon being associated with the computer graphics image;selecting, by the gradient computation hardware, a vector of said plurality of vectors that has a largest first coordinate delta;determining, by the gradient computation hardware, a maximum second coordinate delta using said polygon area and said largest first coordinate delta, wherin the second coordinate delta comprises a distance from a selected vertex of the polygon to an opposing side of the polygon along a line parallel to a coordinate axis;comparing, by the gradient computation hardware, the second coordinate delta to a threshold number of pixels;resolving, by the gradient computation hardware, a second coordinate delta correction value, when the second coordinate delta is less than the threshold; and,when the second coordinate delta is less than the threshold:moving a vertex of the polygon, by the gradient computation hardware, so as to increase the second coordinate delta by the correction value to a corrected second coordinate delta value, wherein the corrected second coordinate delta value is at least equal to the threshold;computing, by the gradient computation hardware, the area of a new polygon using the vertex, the new polygon being associated with vertex data;storing, by the gradient computation hardware, the vertex data into at least a subset of the plurality of image variables, each vertex datum having a magnitude that is within the dynamic range of the at least a subset; and,outputting the vertex data to a display device.