How much of a difference between Voodoo and Blizzardvision?

[Karlos]

@CU

Voodoo has a faster fill rate than the Permedia2 and supports more blending modes. Both are attached by buses that are vastly slower than each chip can make use of.

The fill rate currently makes slighltly less difference than you might expect under warp3D (at least from the test results I had) for 680x0 code as both chips are held back by how quickly the vertex data is processed by the software and fed to the GPU.

Theoretically, for games that use several textures to render a scene (lightmapping in quake engines for instance), the voodoo should be considerably faster since it supports multitexturing but no existing drivers support this yet (AFAIK). That will no doubt change later.

The blendmode issue is actually more important if you want accurate visual quality. The permedia2 can only do alpha blending whereas the Voodoo supports the full spread of alpha and chromatic blending. This makes a difference in the visual quality of games such as quake2, heretic2 etc and blitzquark, all of which need chromatic blending to do the coloured light passing (itself a texturemap), whereas the p2 can only use monochromatic (quake1 sytle) lighting.

[Karlos]

IIRC the pixel64 used a basic Cirrus Logic chipset and shipped with either 2 or 4Mb of RAM (can't say exactly). In any event, it was 2D only.

[Karlos]

It will give you better 2D support, no doubt about it. Normal GUI stuff tends to rely on drawing ractangles and stuff that the gfx chip can do by itself using it's blitter.

-edit-

You can expect higher resolutions and more colourful displays than AGA. Even a basic 2Mb card should be able to deliver 1024x768 in 16-bits (which needs about 1.5Mb of framebuffer).

RTG games should benefit also, but that would ultimately depend on the bus speed and resolution used. For instance, some doom clones ran faster under AGA than they did on Z-II graphics cards since on these systems writing the chunky pixels was limitied by bus speed (even with AGA C2P) so AGA won out there.

Given the ateo bus is a modified ISA bus, I don't know how fast it is capable of.

The pixel64 offers no 3D acceleration of any kind so it won't accelerate 3D games directly, but the chunky pixels should help (unless the bus is slower than AGA, eg Z-II comparable).

[Karlos]

Actually I was referring to the Permedia2 and Voodoo, but the same would hold true for any Mediator/Prometheus/GRex attached gfx card.

Local operations on the card will naturally be very quick, and faster cards will always do better. However, when you have to send lots of information to the GPU, eventually you will hit the bus limit and that will level out most cards currently used.