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SCI32: QFG4 Fix null scaler, climbing by monolith

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Fixes an exception casting Trigger after using grapnel, bug #10837
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Vhati 2018-12-16 22:05:45 -05:00 • committed by Filippos Karapetis
parent 4f761d6002
commit f731760292
1 changed files with 44 additions and 0 deletions
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44
engines/sci/engine/script_patches.cpp
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@ -8995,6 +8995,49 @@ static const uint16 qfg4RestartPatch[] = {
PATCH_END
};
// At the squid monolith (room 800), using the grapnel on the eastern ledge
// disposes hero's scaler to freeze hero's size. A scaler dynamically shrinks
// hero into the horizon as y-pos increases. It makes sense that hero should
// maintain their size while climbing a vertical rope.
//
// Problem: After climbing the rope, both standing on the ledge and back on the
// ground, hero's scaler will remain null. An exception will occur if a script
// calls Prop::setScaler(hero) while hero's scaler is null. Casting Trigger on
// the monolith, from either location, does it. As will climbing down, then
// casting Levitate. Both spells have auras intended to fit hero's size. They
// expect hero to have a scaler, not null.
//
// Ideally the climb script would've swapped in a dummy scaler, then swapped
// the original scaler back upon return to ground level. Implementing that with
// patches would be messy. There's no room to patch setScaler() itself to
// broadly tolerate nulls. That'd avoid exceptions but wouldn't restore normal
// scaling after a climb.
//
// As last resort, we simply leave the original scaler on hero, erasing the
// setScale() call that would freeze hero's size. hero shrinks/grows a little
// while climbing as a side effect.
//
// Applies to at least: English CD, English floppy, German floppy
// Responsible method: sUseTheGrapnel::changeState(5) in script 800
// Fixes bug: #10837
static const uint16 qfg4RopeScalerSignature[] = {
SIG_MAGICDWORD,
0x38, SIG_SELECTOR16(setScale), // pushi setScale
0x76, // push0 (no args, disposes scaler & freezes size)
SIG_ADDTOOFFSET(+14), // ...
0x81, 0x00, // lag global[0] (hero)
0x4a, SIG_UINT16(0x0026), // send 38d
SIG_END
};
static const uint16 qfg4RopeScalerPatch[] = {
0x35, 0x01, // ldi 0 (erase 2 bytes)
0x35, 0x01, // ldi 0 (erase 2 bytes)
PATCH_ADDTOOFFSET(+14+2), // ...
0x4a, PATCH_UINT16(0x0022), // send 34d
PATCH_END
};
// script, description, signature patch
static const SciScriptPatcherEntry qfg4Signatures[] = {
{ true, 0, "prevent autosave from deleting save games", 1, qg4AutosaveSignature, qg4AutosavePatch },
@ -9030,6 +9073,7 @@ static const SciScriptPatcherEntry qfg4Signatures[] = {
{ false, 663, "Floppy: fix crest bookshelf", 1, qfg4CrestBookshelfFloppySignature, qfg4CrestBookshelfFloppyPatch },
{ true, 663, "CD/Floppy: fix crest bookshelf motion", 1, qfg4CrestBookshelfMotionSignature, qfg4CrestBookshelfMotionPatch },
{ true, 800, "fix setScaler calls", 1, qfg4SetScalerSignature, qfg4SetScalerPatch },
{ true, 800, "fix grapnel removing hero's scaler", 1, qfg4RopeScalerSignature, qfg4RopeScalerPatch },
{ true, 803, "fix sliding down slope", 1, qfg4SlidingDownSlopeSignature, qfg4SlidingDownSlopePatch },
{ true, 810, "fix conditional void calls", 1, qfg4ConditionalVoidSignature, qfg4ConditionalVoidPatch },
{ true, 830, "fix conditional void calls", 2, qfg4ConditionalVoidSignature, qfg4ConditionalVoidPatch },