=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Date: 03 June 2001 11:34:13 From: "Rob Santa" To: Subj: sPatch Splines -------------------------------------------------------------------------------- Hi. I was looking at your VRML splines page. I noticed that you had an explanation of "sPatch splines". I don't know how much accurate info you have on sPatch type patches, but I think I can add to the pool. To put it simply, both sPatch and hamaPatch are clones of Hash Animation Master. Animation Master 2000 uses what's called a Hash Patch. In fact Hash Patches are an algorithmically controlled version of Coons Patches and not traditional bicubic bezier surfaces at all. There's now twist vector or basis matrix. Unlike standard 16 point bicubics, Hash Patches (and sPatches) are 12 point patches. The interior 4 points are missing. Read the document carefully and notice that these are not Gregory patches either. I found some of this out at the Animation Master FAQ. I also found a paper written by Martin Hash himself, AM2K creator. It outlines in detail the process. It's a lot simpler than you'd suppose. I've included the paper and the addendums in a ZIP file. These documents should clear everything up.