From 8a94e053a871b6812965cd61f88ae58d897a167e Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Mon, 18 Dec 2023 21:45:27 +0100
Subject: [PATCH] Fix crash when resizing navmesh capacity with crowd created
 for that navmesh

---
 Source/Engine/Navigation/NavMeshRuntime.cpp   | 19 ++++-------
 .../recastnavigation/DetourNavMesh.cpp        | 32 ++++++++++++-------
 .../recastnavigation/DetourNavMesh.h          |  3 ++
 3 files changed, 30 insertions(+), 24 deletions(-)

diff --git a/Source/Engine/Navigation/NavMeshRuntime.cpp b/Source/Engine/Navigation/NavMeshRuntime.cpp
index 989b1697f..4fcf0e038 100644
--- a/Source/Engine/Navigation/NavMeshRuntime.cpp
+++ b/Source/Engine/Navigation/NavMeshRuntime.cpp
@@ -36,7 +36,7 @@ NavMeshRuntime::NavMeshRuntime(const NavMeshProperties& properties)
 
 NavMeshRuntime::~NavMeshRuntime()
 {
-    dtFreeNavMesh(_navMesh);
+    Dispose();
     dtFreeNavMeshQuery(_navMeshQuery);
 }
 
@@ -336,9 +336,7 @@ void NavMeshRuntime::SetTileSize(float tileSize)
     // Dispose the existing mesh (its invalid)
     if (_navMesh)
     {
-        dtFreeNavMesh(_navMesh);
-        _navMesh = nullptr;
-        _tiles.Clear();
+        Dispose();
     }
 
     _tileSize = tileSize;
@@ -363,14 +361,9 @@ void NavMeshRuntime::EnsureCapacity(int32 tilesToAddCount)
     // Ensure to have size assigned
     ASSERT(_tileSize != 0);
 
-    // Fre previous data (if any)
-    if (_navMesh)
-    {
-        dtFreeNavMesh(_navMesh);
-    }
-
-    // Allocate new navmesh
-    _navMesh = dtAllocNavMesh();
+    // Allocate navmesh and initialize the default query
+    if (!_navMesh)
+        _navMesh = dtAllocNavMesh();
     if (dtStatusFailed(_navMeshQuery->init(_navMesh, MAX_NODES)))
     {
         LOG(Error, "Failed to initialize navmesh {0}.", Properties.Name);
@@ -517,7 +510,7 @@ void NavMeshRuntime::RemoveTile(int32 x, int32 y, int32 layer)
     }
 }
 
-void NavMeshRuntime::RemoveTiles(bool (* prediction)(const NavMeshRuntime* navMesh, const NavMeshTile& tile, void* customData), void* userData)
+void NavMeshRuntime::RemoveTiles(bool (*prediction)(const NavMeshRuntime* navMesh, const NavMeshTile& tile, void* customData), void* userData)
 {
     ScopeLock lock(Locker);
     ASSERT(prediction);
diff --git a/Source/ThirdParty/recastnavigation/DetourNavMesh.cpp b/Source/ThirdParty/recastnavigation/DetourNavMesh.cpp
index 2240526eb..eba1b4dc3 100644
--- a/Source/ThirdParty/recastnavigation/DetourNavMesh.cpp
+++ b/Source/ThirdParty/recastnavigation/DetourNavMesh.cpp
@@ -208,21 +208,13 @@ dtNavMesh::dtNavMesh() :
 
 dtNavMesh::~dtNavMesh()
 {
-	for (int i = 0; i < m_maxTiles; ++i)
-	{
-		if (m_tiles[i].flags & DT_TILE_FREE_DATA)
-		{
-			dtFree(m_tiles[i].data);
-			m_tiles[i].data = 0;
-			m_tiles[i].dataSize = 0;
-		}
-	}
-	dtFree(m_posLookup);
-	dtFree(m_tiles);
+	purge();
 }
 		
 dtStatus dtNavMesh::init(const dtNavMeshParams* params)
 {
+    if (m_tiles)
+        purge();
 	memcpy(&m_params, params, sizeof(dtNavMeshParams));
 	dtVcopy(m_orig, params->orig);
 	m_tileWidth = params->tileWidth;
@@ -1178,6 +1170,24 @@ int dtNavMesh::getMaxTiles() const
 	return m_maxTiles;
 }
 
+void dtNavMesh::purge()
+{
+	for (int i = 0; i < m_maxTiles; ++i)
+	{
+		if (m_tiles[i].flags & DT_TILE_FREE_DATA)
+		{
+			dtFree(m_tiles[i].data);
+			m_tiles[i].data = 0;
+			m_tiles[i].dataSize = 0;
+		}
+	}
+    m_maxTiles = 0;
+	dtFree(m_posLookup);
+    m_posLookup = 0;
+	dtFree(m_tiles);
+    m_tiles = 0;
+}
+
 dtMeshTile* dtNavMesh::getTile(int i)
 {
 	return &m_tiles[i];
diff --git a/Source/ThirdParty/recastnavigation/DetourNavMesh.h b/Source/ThirdParty/recastnavigation/DetourNavMesh.h
index 4c1277d78..8837d576d 100644
--- a/Source/ThirdParty/recastnavigation/DetourNavMesh.h
+++ b/Source/ThirdParty/recastnavigation/DetourNavMesh.h
@@ -613,6 +613,9 @@ private:
 	dtNavMesh(const dtNavMesh&);
 	dtNavMesh& operator=(const dtNavMesh&);
 
+    /// Clears all tiles from memory. Can be called before init to rebuild navigation mesh with different parameters.
+    void purge();
+
 	/// Returns pointer to tile in the tile array.
 	dtMeshTile* getTile(int i);