[Scummvm-tracker] [ScummVM :: Bugs] #13966: SCI: Way too fast color cycling in LONGBOW

[ScummVM :: Bugs]

#13966: SCI: Way too fast color cycling in LONGBOW
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Reporter:  GermanTribun  |       Owner:  sluicebox
    Type:  defect        |      Status:  closed
Priority:  normal        |   Component:  Engine: SCI
 Version:                |  Resolution:  fixed
Keywords:                |        Game:  Conquests of the Longbow
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Changes (by sluicebox):

 * owner:  (none) => sluicebox
 * status:  new => closed
 * resolution:   => fixed

Comment:

 Map rooms fixed in:
 https://github.com/scummvm/scummvm/commit/e46767b8f8acd7ddcb6a11e4d794d7889c243ca6

 Speed throttling is no longer broken on the maps, and I've patched out
 Sierra's incompatible map throttling script. Without that second part they
 would go way too slow. It's now the speed I get with DOSBox at 3,000 clock
 cycles per second.

 Yes, timing is "tricky" in SCI, and I don't think it's such a battle for
 the SCUMM folks. Thanks again for reporting, this has revealed that the 12
 year old heuristic code that detects Sierra's speed tests does indeed make
 mistakes that cause problems. It's mostly obsolete due to improvements
 from this year, but it wasn't clear if it could be safely removed. Now we
 can work on figuring that out.

 Only the map rooms were broken, the other game rooms that palette cycle
 are scripted to change once per game cycle with no throttling, and that's
 what they're doing. There is no original speed for these unthrottled
 games, they do as many game cycles as the hardware will allow. And
 Sierra's invisible speed test tweaks individual behaviors based on the
 result. That particular youtube video is running DOSBox (DOS?) painfully
 slow, hence the slower animation and long load times when switching rooms.
 It's hard to reason about this stuff without looking at the scripts
 because different scenes are programmed differently. (I'm being polite:
 inconsistently.) They could have used clock time for consistent palette
 animation speed like in QFG1VGA, but instead they used game cycles for
 everything. Oops.

 Some fun numbers: ScummVM limits SCI games to ~33 game cycles per second.
 My ~1995 DOS machine gets 176 at the hideout, and so the palette animation
 screams. The map animates just as fast as ScummVM does now. Unthrottled,
 ScummVM would do 2,7000 at the hideout on my mediocre laptop. (I modded
 the game to show speed) Adjusting DOSBox speed affects game cycles
 accordingly, along with animations tied to game cycles.
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Ticket URL: <https://bugs.scummvm.org/ticket/13966#comment:5>
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