Circuit for determining non-homogenous second order perspective texture mapping coordinates using linear interpolation

US6052127A · kind A · utility

Assignee

• CIRRUS LOGIC, INC. · US

Inventors

• Gautam P. Vaswani · Austin, US
• Michael K. Larson · Kirkland, US
• Tom A. Dye · Austin, US
• Daniel P. Wilde · Cedar Park, US

Key dates

• Filing date: Dec 30, 1996
• Grant date: Apr 18, 2000
• Expiry date: Dec 30, 2016

Classification

• Technology area (CPC G): Physics
• CPC primary: G06T15/04
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

A texture value determining (TVD) circuit approximates non-homogenous 2nd order perspective texture mapping to provide texture for a polygon using linear interpolation and input parameters. The TVD circuit of the present invention includes a vertical walk subcircuit and an orthogonal walk subcircuit. The vertical walk subcircuit determines texture coordinates, u(a.sub.0,n) and v(a.sub.0,n) that represent the pixels along a vertical main slop of a triangle polygon. The orthogonal walk subcircuit determines texture coordinates, u(a.sub.m,n) and v(a.sub.m,n), for orthogonally walked polygon coordinate positions for which m>0. The orthogonally walked coordinate positions represent individual scan lines. The vertical walk subcircuit of the TVD circuit includes adders, latches, and accumulators. Each element of the vertical walk subcircuit receives a vertical main slope clock (n-clock) signal. An output of the vertical walk subsystem is computed based on the relationship, EQU u(a.sub.0,n)=u(a.sub.0, n-1)+du.sub.main +(n-1)d.sup.2 u.sub.main for m=0, n>0 where du.sub.main and d.sup.2 u.sub.main are input parameters. The orthogonal walk subcircuit also includes adders, latches, and accumul…