[Scummvm-tracker] [ScummVM :: Bugs] #10270: SCI: LSL7: Ocean outside portholes jumps

[ScummVM :: Bugs]

#10270: SCI: LSL7: Ocean outside portholes jumps
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Reporter:  DanielSWolf  |       Owner:  (none)
    Type:  defect       |      Status:  new
Priority:  normal       |   Component:  Engine: SCI
 Version:               |  Resolution:
Keywords:  sci32        |        Game:  Leisure Suit Larry 7
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Comment (by sluicebox):

 There are two problems with the ocean motion:

 1. Two big jumps around the end of the ocean cycle. This is what the bug
 report is describing. This is due to our implementation of the modulo
 opcode (mod) being incorrect for this game. YIKES! Sierra rewrote it in
 assembly in SCI2.1 Late / SCI3 and changed it to treat the dividend as
 unsigned.

 2. Mild jitter at the top and bottoms of some of the waves. This is due to
 different results from ScummVM's implementation of the kSinMult and
 kMulDiv functions versus Sierra's, as csnover identified. I also
 experimented with an implementation of SSCI-accurate versions, and that
 fixes the jitter.

 I fixed the modulo bug so the big jumps are now fixed:
 https://github.com/scummvm/scummvm/commit/34664be3d35734a9e6f2ccaaf111af9c66a8bcb1

 We can do the trigonometry functions later; the big bug is fixed for now.
-- 
Ticket URL: <https://bugs.scummvm.org/ticket/10270#comment:5>
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