3dfx's patent :
http://www.patents.ibm.com/details?patent_number=5740343
Their patent essentially claims they own the idea of having a device
(apparatus) that combines textured pixel's (refered to as a signal) with
any blend algorithm, as well as the method it uses to do it. It also
mentions that one of the features is to be able to use it serialially, so
that you can do triple, quadruple, etc. multitexturing.
It sounds like a very lame (weak) patent. A texture-map is an image, and
image blending has been around much longer then their filed claims. They
laid claim to something merely because it has a diffrent name. If we
refered to textures as images, they would not have a valid patent, how many
apparatus's have been invented for blending (compositing) images. Keep in
mind an apparatus can exist in software in the form of a function or
algorithm as well as hardware.
CitiZen X