From 0a296c5a5f8e292bda46630f0dbb415132d1cc31 Mon Sep 17 00:00:00 2001
From: Kawe Mazidjatari <48657826+Mauler125@users.noreply.github.com>
Date: Fri, 5 Jul 2024 22:24:54 +0200
Subject: [PATCH] Recast: fix group merging bug in static path building

Don't merge poly islands under the same group id if there's an off-mesh connection linking the 2. The off-mesh connection polygon also gets its own group id now.

The reason we don't want to merge them is because not all ai can take the off-mesh link under on the same navmesh, and if we merge them the ai would still try and reach a goal poly it couldn't, causing it to become hard stuck on the poly island's boundary.
---
 .../Detour/Source/DetourNavMeshBuilder.cpp    | 30 ++++++++++++-------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/src/thirdparty/recast/Detour/Source/DetourNavMeshBuilder.cpp b/src/thirdparty/recast/Detour/Source/DetourNavMeshBuilder.cpp
index a3880311..60a806aa 100644
--- a/src/thirdparty/recast/Detour/Source/DetourNavMeshBuilder.cpp
+++ b/src/thirdparty/recast/Detour/Source/DetourNavMeshBuilder.cpp
@@ -320,19 +320,27 @@ bool dtCreateStaticPathingData(dtNavMesh* nav)
 		{
 			dtPoly& poly = tile->polys[j];
 			unsigned int plink = poly.firstLink;
-			while (plink != DT_NULL_LINK)
+
+			// Off-mesh connections need their own ID's
+			if (poly.getType() != DT_POLYTYPE_OFFMESH_CONNECTION)
 			{
-				const dtLink l = tile->links[plink];
-				const dtMeshTile* t;
-				const dtPoly* p;
-				nav->getTileAndPolyByRefUnsafe(l.ref, &t, &p);
+				while (plink != DT_NULL_LINK)
+				{
+					const dtLink l = tile->links[plink];
+					const dtMeshTile* t;
+					const dtPoly* p;
+					nav->getTileAndPolyByRefUnsafe(l.ref, &t, &p);
 
-				if (p->groupId != (unsigned short)-1)
-					nlabels.insert(p->groupId);
+					if (p->groupId != (unsigned short)-1)
+						nlabels.insert(p->groupId);
 
-				plink = l.next;
+					plink = l.next;
+				}
 			}
-			if (nlabels.empty())
+
+			const bool noLabels = nlabels.empty();
+
+			if (noLabels)
 			{
 				// This poly isn't connected to anything, mark it so the game
 				// won't consider this poly in path generation.
@@ -349,7 +357,9 @@ bool dtCreateStaticPathingData(dtNavMesh* nav)
 				for (const int nl : nlabels)
 					data.setUnion(l, nl);
 			}
-			nlabels.clear();
+
+			if (!noLabels)
+				nlabels.clear();
 		}
 	}