Recast: fix bugs causing mesh links to leak when removing and readding tiles

Rework the way traverse links are tracked and how the traverse table gets recreated when a tile gets removed/added. We would rebuild the entire traverse network and thus leak links since we also cleared the map that tracks the connections.

src/naveditor/Editor.cpp

@@ -783,6 +783,8 @@ void Editor::connectTileTraverseLinks(dtMeshTile* const baseTile, const bool lin
 		return;
 
 	const dtMeshHeader* baseHeader = baseTile->header;
+	const dtPolyRef basePolyRefBase = m_navMesh->getPolyRefBase(baseTile);
+
 	bool firstBaseTileLinkUsed = false;
 
 	for (int i = 0; i < baseHeader->polyCount; ++i)
@@ -847,6 +849,8 @@ void Editor::connectTileTraverseLinks(dtMeshTile* const baseTile, const bool lin
 					continue;
 
 				const dtMeshHeader* landHeader = landTile->header;
+				const dtPolyRef landPolyRefBase = m_navMesh->getPolyRefBase(landTile);
+
 				bool firstLandTileLinkUsed = false;
 
 				for (int l = 0; l < landHeader->polyCount; ++l)
@@ -942,7 +946,10 @@ void Editor::connectTileTraverseLinks(dtMeshTile* const baseTile, const bool lin
 								continue;
 						}
 
-						const TraverseLinkPolyPair linkedPolyPair(basePoly, landPoly);
+						const dtPolyRef basePolyRef = basePolyRefBase | i;
+						const dtPolyRef landPolyRef = landPolyRefBase | l;
+
+						const TraverseLinkPolyPair linkedPolyPair(basePolyRef, landPolyRef);
 						auto linkedIt = m_traverseLinkPolyMap.find(linkedPolyPair);
 
 						bool traverseLinkFound = false;
@@ -992,7 +999,7 @@ void Editor::connectTileTraverseLinks(dtMeshTile* const baseTile, const bool lin
 
 						dtLink* const forwardLink = &baseTile->links[forwardIdx];
 
-						forwardLink->ref = m_navMesh->getPolyRefBase(landTile) | (dtPolyRef)l;
+						forwardLink->ref = landPolyRef;
 						forwardLink->edge = (unsigned char)j;
 						forwardLink->side = landSide;
 						forwardLink->bmin = 0;
@@ -1005,7 +1012,7 @@ void Editor::connectTileTraverseLinks(dtMeshTile* const baseTile, const bool lin
 
 						dtLink* const reverseLink = &landTile->links[reverseIdx];
 
-						reverseLink->ref = m_navMesh->getPolyRefBase(baseTile) | (dtPolyRef)i;
+						reverseLink->ref = basePolyRef;
 						reverseLink->edge = (unsigned char)m;
 						reverseLink->side = baseSide;
 						reverseLink->bmin = 0;
@@ -1030,6 +1037,8 @@ void Editor::connectTileTraverseLinks(dtMeshTile* const baseTile, const bool lin
 bool Editor::createTraverseLinks()
 {
 	rdAssert(m_navMesh);
+	m_traverseLinkPolyMap.clear();
+
 	const int maxTiles = m_navMesh->getMaxTiles();
 
 	// First pass to connect edges between external tiles together.
@@ -1052,7 +1061,6 @@ bool Editor::createTraverseLinks()
 		connectTileTraverseLinks(baseTile, false);
 	}
 
-	m_traverseLinkPolyMap.clear();
 	return true;
 }
 

src/naveditor/Editor_TileMesh.cpp

@@ -243,8 +243,6 @@ public:
 					m_editor->removeTile(m_hitPos);
 				else
 					m_editor->buildTile(m_hitPos);
-
-				m_editor->buildStaticPathingData();
 			}
 			else if (m_cursorMode == TT_CURSOR_MODE_DEBUG)
 			{
@@ -727,6 +725,18 @@ void Editor_TileMesh::buildTile(const float* pos)
 						m_navMesh->connectExtOffMeshLinks(targetRef);
 				}
 			}
+
+			dtMeshTile* tile = (dtMeshTile*)m_navMesh->getTileByRef(tileRef);
+
+			// Reconnect the traverse links.
+			connectTileTraverseLinks(tile, true);
+			connectTileTraverseLinks(tile, false);
+
+			dtTraverseTableCreateParams params;
+			createTraverseTableParams(&params);
+
+			dtCreateDisjointPolyGroups(&params);
+			updateStaticPathingData(&params);
 		}
 	}
 	
@@ -768,7 +778,34 @@ void Editor_TileMesh::removeTile(const float* pos)
 	getTileExtents(tx, ty, m_lastBuiltTileBmin, m_lastBuiltTileBmax);
 	
 	m_tileCol = duRGBA(255,0,0,180);
-	m_navMesh->removeTile(m_navMesh->getTileRefAt(tx,ty,0),0,0);
+	const dtTileRef tileRef = m_navMesh->getTileRefAt(tx,ty, 0);
+
+	if (dtStatusSucceed(m_navMesh->removeTile(tileRef, 0, 0)))
+	{
+		// Update traverse link map so the next time we rebuild this
+		// tile, the polygon pairs will be marked as available.
+		const unsigned int tileId = m_navMesh->decodePolyIdTile(tileRef);
+
+		for (auto it = m_traverseLinkPolyMap.cbegin(); it != m_traverseLinkPolyMap.cend();)
+		{
+			const TraverseLinkPolyPair& pair = it->first;
+
+			if (m_navMesh->decodePolyIdTile(pair.poly1) == tileId || 
+				m_navMesh->decodePolyIdTile(pair.poly2) == tileId)
+			{
+				it = m_traverseLinkPolyMap.erase(it);
+				continue;
+			}
+
+			++it;
+		}
+
+		dtTraverseTableCreateParams params;
+		createTraverseTableParams(&params);
+
+		dtCreateDisjointPolyGroups(&params);
+		updateStaticPathingData(&params);
+	}
 }
 
 void Editor_TileMesh::buildAllTiles()
@@ -837,6 +874,8 @@ void Editor_TileMesh::removeAllTiles()
 	for (int y = 0; y < th; ++y)
 		for (int x = 0; x < tw; ++x)
 			m_navMesh->removeTile(m_navMesh->getTileRefAt(x,y,0),0,0);
+
+	m_traverseLinkPolyMap.clear();
 }
 
 void Editor_TileMesh::buildAllHulls()

src/naveditor/include/Editor.h

@@ -194,7 +194,7 @@ enum EditorPolyFlags
 
 struct TraverseLinkPolyPair
 {
-	TraverseLinkPolyPair(const dtPoly* p1, const dtPoly* p2)
+	TraverseLinkPolyPair(dtPolyRef p1, dtPolyRef p2)
 	{
 		if (p1 > p2)
 			rdSwap(p1, p2);
@@ -213,8 +213,8 @@ struct TraverseLinkPolyPair
 		return poly2 < other.poly2;
 	}
 
-	const dtPoly* poly1;
-	const dtPoly* poly2;
+	dtPolyRef poly1;
+	dtPolyRef poly2;
 };
 
 class EditorDebugDraw : public DebugDrawGL

src/thirdparty/recast/Detour/Source/DetourNavMeshBuilder.cpp

@@ -316,6 +316,15 @@ bool dtCreateDisjointPolyGroups(const dtTraverseTableCreateParams* params)
 				while (plink != DT_NULL_LINK)
 				{
 					const dtLink l = tile->links[plink];
+
+					// Polygons linked with traverse links are not necessarily on
+					// the same group, these should be skipped.
+					if (l.traverseType != DT_NULL_TRAVERSE_TYPE)
+					{
+						plink = l.next;
+						continue;
+					}
+
 					const dtMeshTile* t;
 					const dtPoly* p;
 					nav->getTileAndPolyByRefUnsafe(l.ref, &t, &p);