| After some testing I can say that :
OpenGL 3D acceleration is working nice again in latest versions of Xorg 7.2 and Mesa, as long as you provide a Glide3x library ([url=http://www.3dfxzone.it/enboard/topic.asp?TOPIC_ID=3262]as discussed elsewhere[/url]).
Also a couple of extensions are supported like GLX_EXT_texture_from_pixmap (necessary for compositing = drawing windows not onto screen, but into buffers and then using those buffers as texture inside compiz).
But ! This is not sufficient !
- Currently 3DFx drivers only supports power-of-two texture sizes (256, 1024 or 2048 pixel wide texture, for exemple, but nothing in between). This is a problem for compiz, because it uses the windows' buffers as texture for compositing and those windows could be any size, not only powers of two. Also, I currently don't remember if it's a hardware limitation (VSA-100 can only do power-of-two textures), Glide limitation (Glide is partially used as a backend for Mesa3D on Voodoo) or if the openGL driver is only too old (quite possible that everything is ready for arbitrarily-sized textures but wasn't implemented yet).
Also other non-critical obstacles :
- VSA-100 can't do AGP texturing, i.e.: It can't autonomously pull textures from main memory. Thus buffers with windows content have to be manually loaded into GPU memory.
- typical (unmodified) Voodoo have low memory. But for 3D-hardware assisted compositing you must allocation enough memory for double buffering + enough memory to hold the buffer with the content of every window (as I said, no AGP-texturing). So even if the texture-size problem is corrected, you'll be still limited to lower resolution where everything can fit inside the 32Mo per VSA-100 (64 with modified Voodoo 4s)