Anisotropic texture mapping using silhouette/footprint analysis in a computer image generation system

DETAILED DESCRIPTION In accordance with the invention, a method for anisotropically mapping texture information to each pixel required for display of each of plural polygons forming each scene on a CIG display in a computational efficient manner, uses the footprint of each transformed pixel, as mapped into the texture array, to determine an anisotropic texture space area having both a related length and a related width, in which complete texels and texels fractions are covered by that pixel footprint.
Use of a set of un-normalized line equations characterizing a particular pixel footprint is used to determine whether each texel in the vicinity of that pixel footprint is either enclosed or avoided by (i.
e.
inside or outside of) that projected pixel footprint.
By use of an isotropic 2D area, rather than a 1D line (which is only proper for very high aspect ratios {typically greater than 70.
degree.
}), this method allows for tallying of the included full texels or texel fractions, so as to determine the color and/or translucency of the pixel.
Since all values are determined incrementally, my methods initially require the computation of a few values, followed by a simple incrementing procedure to tally which texels are included in the footprint and which are not.
If the texels are subdivided into 2 or more subtexels, each subtexel can also be determined to be inside or outside of the pixel footprint, permitting more accurate texture mapping.
A pixel is mapped into a higher resolution texture map than its effective isotropic LOD would indicate.
The projected pixel overlaps a number of texels in all direction.
Accordingly, it is one object of the present invention to provide novel method and apparatus for the anisotropic texturing of image space pixels using an areal projection and silhouette analysis.
This and other objects of the present invention will become apparent to those skilled in the art, upon consideration of the appended drawings and reading of the associated detailed description of a presently preferred embodiment