SCI32: Fix QFG4 forest pathfinding

Adds workarounds for odd detours during entry, bugs #10857, #10858

2 files changed, 46 insertions, 9 deletions

diff --git a/engines/sci/engine/kpathing.cpp b/engines/sci/engine/kpathing.cpp
index 3d5ef4752b..fb1183e8d7 100644
--- a/engines/sci/engine/kpathing.cpp
+++ b/engines/sci/engine/kpathing.cpp
@@ -1407,15 +1407,22 @@ static void AStar(PathfindingState *s) {
 			// This difference might lead to problems, but none are
 			// known at the time of writing.
 
-			// WORKAROUND: This check fails in QFG1VGA, room 81 (bug report #3568452).
-			// However, it is needed in other SCI1.1 games, such as LB2. Therefore, we
-			// add this workaround for that scene in QFG1VGA, until our algorithm matches
-			// better what SSCI is doing. With this workaround, QFG1VGA no longer freezes
-			// in that scene.
-			bool qfg1VgaWorkaround = (g_sci->getGameId() == GID_QFG1VGA &&
-									  g_sci->getEngineState()->currentRoomNumber() == 81);
-
-			if (s->pointOnScreenBorder(vertex->v) && !qfg1VgaWorkaround)
+			// WORKAROUND: This check is needed in SCI1.1 games, such as LB2. Until our
+			// algorithm matches better what SSCI is doing, we exempt certain rooms where
+			// the check fails.
+			bool penaltyWorkaround =
+				// QFG1VGA room 81 - Hero gets stuck when walking to the SE corner (bug #6140).
+				(g_sci->getGameId() == GID_QFG1VGA && g_sci->getEngineState()->currentRoomNumber() == 81) ||
+#ifdef ENABLE_SCI32
+				// QFG4 room 563 - Hero zig-zags into the room (bug #10858).
+				// Entering from the south (564) off-screen behind an obstacle, hero
+				// fails to turn at a point on the screen edge, passes the poly's corner,
+				// then approaches the destination from deeper in the room.
+				(g_sci->getGameId() == GID_QFG4 && g_sci->getEngineState()->currentRoomNumber() == 563) ||
+#endif
+				false;
+
+			if (s->pointOnScreenBorder(vertex->v) && !penaltyWorkaround)
 				new_dist += 10000;
 
 			if (new_dist < vertex->costG) {
diff --git a/engines/sci/engine/script_patches.cpp b/engines/sci/engine/script_patches.cpp
index 250aefb556..8f0b795d2e 100644
--- a/engines/sci/engine/script_patches.cpp
+++ b/engines/sci/engine/script_patches.cpp
@@ -9473,6 +9473,35 @@ static const uint16 qfg4PitRopeMagePatch2[] = {
 	PATCH_END
 };
 
+// WORKAROUND: Script needed, because of differences in our pathfinding
+// algorithm.
+// When entering forest room 557 from the east (563), hero is supposed to move
+// only a short distance into the room. ScummVM's pathfinding sends hero off
+// course, to the middle of the room and back.
+//
+// There's an unwalkable stream in the SE corner, and hero's coords were within
+// its polygon. We lower the top two points to keep hero on the outside.
+//
+// Applies to at least: English CD, English floppy, German floppy
+// Responsible method: rm557::init() in script 557
+// Fixes bug: #10857
+static const uint16 qfg4Forest557PathfindingSignature[] = {
+	SIG_MAGICDWORD,
+	0x38, SIG_UINT16(0x0119),           // pushi 281d (point 3)
+	0x38, SIG_UINT16(0x0087),           // pushi 135d
+	0x38, SIG_UINT16(0x013f),           // pushi 319d (point 4)
+	0x38, SIG_UINT16(0x0087),           // pushi 135d
+	SIG_END
+};
+
+static const uint16 qfg4Forest557PathfindingPatch[] = {
+	PATCH_ADDTOOFFSET(+3),
+	0x38, PATCH_UINT16(0x0089),         // pushi 137d
+	PATCH_ADDTOOFFSET(+3),
+	0x38, PATCH_UINT16(0x0089),         // pushi 137d
+	PATCH_END
+};
+
 //          script, description,                                     signature                      patch
 static const SciScriptPatcherEntry qfg4Signatures[] = {
 	{  true,     0, "prevent autosave from deleting save games",   1, qfg4AutosaveSignature,         qfg4AutosavePatch },
@@ -9501,6 +9530,7 @@ static const SciScriptPatcherEntry qfg4Signatures[] = {
 	{  true,   542, "fix setLooper calls (1/2)",                   5, qfg4SetLooperSignature1,       qfg4SetLooperPatch1 },
 	{  true,   543, "fix setLooper calls (1/2)",                   5, qfg4SetLooperSignature1,       qfg4SetLooperPatch1 },
 	{  true,   545, "fix setLooper calls (1/2)",                   5, qfg4SetLooperSignature1,       qfg4SetLooperPatch1 },
+	{  true,   557, "fix forest 557 entry from east",              1, qfg4Forest557PathfindingSignature, qfg4Forest557PathfindingPatch },
 	{  true,   630, "fix great hall entry from barrel room",       1, qfg4GreatHallEntrySignature,   qfg4GreatHallEntryPatch },
 	{  true,   633, "fix stairway pathfinding",                    1, qfg4StairwayPathfindingSignature, qfg4StairwayPathfindingPatch },
 	{  true,   643, "fix iron safe's east door sending hero west", 1, qfg4SafeDoorEastSignature,     qfg4SafeDoorEastPatch },