The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 24, 1998
Filed:
Dec. 30, 1996
Mark Alan Einkauf, Leander, TX (US);
Michael Kerry Larson, Austin, TX (US);
Cirrus Logic, Inc., Fremont, CA (US);
Abstract
A method for computing input parameters used in a non-homogeneous second order perspective texture mapping process using interpolation. The present invention receives a polygon primitive (e.g., triangle) including screen display coordinates and texture map coordinates for each vertex (vmin, vmid, and vmax). Based on vertex information including perspective weights, w, screen display coordinates and texture map coordinates are determined for midpoints (i and j) of the two triangle slopes opposite the triangle's major slope. Based on a determined quadratic equation of the triangle's major slope, screen coordinates and texture map coordinates are determined at several selected points (e.g., imain, jmain, and midmain) along the major slope that corresponds to the i, j, and vmid points. From these values, quadratic coefficients a1, a2, and du.sub.-- ortho.sub.-- add are computed and also quadratic coefficients b1, b2 and dv.sub.-- ortho.sub.-- add are computed. The above values, parameters u.sub.-- main, du.sub.-- main (change in u over change in y), d2u.sub.-- main (change in .DELTA.u over change in .DELTA.y), du.sub.-- ortho (change in u over change in x), d2u.sub.-- ortho (change in .DELTA.u over change in .DELTA.x), v.sub.-- main, dv.sub.-- main (change in v over change in y), d2v.sub.-- main (change in .DELTA.v over change in .DELTA.y), dv.sub.-- ortho (change in v over change in x), and d2v.sub.-- ortho (change in .DELTA.v over change in .DELTA.x) are computed and forwarded to a non-homogenous second order perspective texture mapping process using interpolation. The above texture mapping process is extremely efficient as it is free of division operations during the interpolation.