Patent ID: 6518974
Filing Date: 2003-02-11
Classification: G06F,G09G

Abstract:
A method for determining the rate of change of texture address variables U and V as a function of address variables x and y of a pixel, wherein,U is the texture coordinate of the pixel in the S direction V is the texture coordinate of the pixel in the T direction W is the homogenous w value of the pixel (typically the depth value) Inv_W is the inverse of W C0n is the value of attribute n at some reference point. (xâ€²=0, yâ€²=0) CXn is the change of attribute n for one pixel in the raster x direction CYn is the change of attribute n for one pixel in the raster y direction n includes S=U/W and T=V/W x is the screen coordinate of the pixel in the x raster direction y is the screen coordinate of the pixel in the y raster direction the method comprising the steps of: calculate the start value and rate of change in raster x,y direction for the attribute T resulting in C0s, CXs, Cys; calculate the start value and rate of change in the raster x,y direction for the attribute T, resulting in C0t, CXt, Cyt; calculate the start value and rate of change in the raster x,y direction for the attribute 1/W, resulting in C0inv_W, CXinv_W, CYinv_W; calculate the perspective correct values of U and V resulting in U=C0s+CXs*X+CYs*YC0inv_w+CXinv_w*X+CYinv_w*YV=C0t+CXt*X+CYt*YC0inv_w+CXinv_w*X+CYinv_w*Yâ€ƒCalculate the rate of change of texture address variables U and V as a function of address variables x and y, resulting in &dd;u&dd;x=W*[CXs-U*CXinv_w]&dd;u&dd;y=W*[CYs-U*CYinv_w]&dd;v&dd;y=W*[CYt-V*CYinv_w]&it;â€ƒ.