HP Labs Technical Reports

Rational - Linear Interpolation of Texture Coordinates and Their Partial Derivatives

Wu, Kevin

HPL-98-113

Keyword(s): computer graphics; texture mapping; interpolation; texture coordinates; texture derivatives; anti- aliasing

Abstract: This paper describes an algorithm for calculating texture coordinates and their partial derivatives during scan conversion of planar polygons. These values are required in texture mapping for anti- aliasing algorithms, where a resampling filter combines texture elements (a.k.a. texels) in a weighted average. Perspective projection requires an image warp accomplished with rational-linear (a.k.a. hyperbolic) interpolation. A single division per pixel and a few addition and multiplication operations yields the texture coordinates and their partial derivatives.

13 Pages

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