Sega Saturn Development > General discussion about the Sega Saturn

Idea of UV mapping on the Saturn

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20EnderDude20:
Well, how do other systems like the Jaguar pull this off at a better framerate? Is it because it has a higher bandwidth, or...? This is more of asking if we can remake Supercross 3d on the Sega Saturn.

Jorhlok:

--- Quote from: ponut64 on August 11, 2018, 10:49:05 pm ---More to the point, it's pre-processed; the image on the sphere is pretty much just a screenshot. You'll notice the heavy lag time before the ball comes into play after the game stops.

--- End quote ---

Oh yeah, the background wouldn't be in the VDP1 framebuffer so it would necessarily need to be touched up to include what the VDP2 would normally produce.

ponut64:

--- Quote from: 20EnderDude20 on August 12, 2018, 12:23:21 am ---Well, how do other systems like the Jaguar pull this off at a better framerate? Is it because it has a higher bandwidth, or...? This is more of asking if we can remake Supercross 3d on the Sega Saturn.

--- End quote ---

The Jaguar might do it because it has less data to handle in a more compressed format in a more unified memory access structure.
Heavily segmented memory [on the Saturn] has its advantages but speed definitely is not one of them.

Now, we wonder: How, on the Saturn, would we do this?
I imagine it would involve use of one of VDP2's rotating background layers and a lot of memory copies, possibly even compression, or culling of certain assets from the memory copy to a TGA / bitmap format that VDP2 understands.

In other words:
Stream frame-buffer of VDP1 to a work area where it can be processed to a bitmap format and re-pasted to VDP2 RBG0 area, line-by-line (line being a chunk of the stream).
You can then move, scale, and rotate this effective re-projection wherever you like in 3D space.
Problems:
1. Extraordinarily busy on DMAs, cannot happen in concurrence with music streams, file system access, or SCU DSP access.
2. Quite slow, I don't foresee it working beyond 10 FPS.
3. Effectively limits the scene complexity to what can fit into RBG0 data area [130KB?].

20EnderDude20:
Maybe you can make it go at 1-2 fps, just make it a billboard, or demonstrate what is the best trade-off with using compression.

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