Crazy idea to improve speed on games for AGA machines

[sonninnos]

Oh man, if only Stunt Car Racer could be as smooth as the C64 SuperCPU version, instead of just faster..

[DanyPPC]

Well done jotd !

I played SuperCars 2 AGA 0.89 on A1200/BlizzIV and A1200/ACA1233 and the framerate/speed is better than previous 0.88 version.

On WinUAE this improvement isn't visible.

[turrican3]

You know exactly what i will propose : shadow warriors.

[jotd]

Originally Posted by Toni Wilen

It should be relatively easy if game does not use horizontal scrolling.

Horizontal scrolling can make it very complex task. Bitplane pointers must be 8 bytes divisible, different BPLCON1 range (0-15 -> 0-63). Horizontal scrolling also requires smaller DDFSTRT (than OCS/ECS) = lost sprites.

horizontal scrollers (not using the blitter) are not an easy task...

ECS: bitplanes aligned on 2 bytes, BPLCON1 scroller shift 0-15 bits
AGA FMODE=3: bitplanes aligned on 8 bytes, BPLCON1 scroller shift upgraded to 0-63 bits.

Means that a lot of reverse engineering must be done to adapt those games.

[vulture]

@jotd

I tried Chase HQ II on WinUAE and saw no real difference compared to the real thing, so, I guess the ICE racers will remain crappy as they currently are.

@turrican3

Great idea, I just hope it's one of those that can be improved as I recall it also plays the same way under WinUAE as on the real system.

[Aardvark]

Top Gear 2 (OCS) Road updates every 1/3 frames in cycle-exact mode (68020), 1/2 frames in non-cycle-exact.

Top Gear 2 (AGA) 1/5 frames in cycle-exact, 1/2 in non-cycle-exact

Power Drift: Framerate fluctuates between 1/5 and 1/10 in cycle-exact, 1/3 to 1/5 in non-cycle-exact.

FIFA International Soccer: 1/2 to 1/3 frames scrolling in cycle-exact, 1/1 in non-cycle-exact.

[jotd]

Originally Posted by DanyPPC

Well done jotd !

I played SuperCars 2 AGA 0.89 on A1200/BlizzIV and A1200/ACA1233 and the framerate/speed is better than previous 0.88 version.

On WinUAE this improvement isn't visible.

Coincidence? I just sold more than 10 copies of the game today!

As Toni reminded, for a lot of games it will be simply too difficult because of horizontal scrolling. Supercars 2 doesn't really scroll, everything is blitted on screen each time. Why it runs so fast, maybe it's because the background is not made of tiles, so there are "only" 7 calls to the blitter. Redrawing the same surface but with small tiles takes more time, and most tiled games use hardware scrolling. Blitting the whole background each time is costly, but avoids to erase the objects prior to redrawing. Good tradeoff, very well executed by Shaun Southern, an inspiring programmer.

Not using hardware scrolling allowed Supercars 2 to have a 2 player mode with vertical split screen. Not sure it's possible using hardware scrolling.

So once again this is happening with a bit of luck for Supercars 2:

- source code available and which can be easily rebuilt (not sure anyone can rebuild Jim Power or Turrican 3)
- 256 color pics available to replace old 64 color EHB ones
- FMODE possible thanks to blitter scrolling
- more color for cars: easy way to enhance the visuals without redrawing all graphics
- module player that can play modules & sounds at the same time (and reusing Lotus tunes, and getting original J.M.D/saimon69 original tunes too)
- programmer (me) who loves that game

[dlfrsilver]

Originally Posted by jotd

Coincidence? I just sold more than 10 copies of the game today!

As Toni reminded, for a lot of games it will be simply too difficult because of horizontal scrolling. Supercars 2 doesn't really scroll, everything is blitted on screen each time. Why it runs so fast, maybe it's because the background is not made of tiles, so there are "only" 7 calls to the blitter. Redrawing the same surface but with small tiles takes more time, and most tiled games use hardware scrolling. Blitting the whole background each time is costly, but avoids to erase the objects prior to redrawing. Good tradeoff, very well executed by Shaun Southern, an inspiring programmer.

Not using hardware scrolling allowed Supercars 2 to have a 2 player mode with vertical split screen. Not sure it's possible using hardware scrolling.

So once again this is happening with a bit of luck for Supercars 2:

- source code available and which can be easily rebuilt (not sure anyone can rebuild Jim Power or Turrican 3)
- 256 color pics available to replace old 64 color EHB ones
- FMODE possible thanks to blitter scrolling
- more color for cars: easy way to enhance the visuals without redrawing all graphics
- module player that can play modules & sounds at the same time (and reusing Lotus tunes, and getting original J.M.D/saimon69 original tunes too)
- programmer (me) who loves that game

Turrican 3 can be. You need to prepare an extended ADF and activate Winuae Longtrack option in the config file you use.

Then you use the script and you write the master disk.