Recast: initial working implementation of traverse link generation algorithm

Traversing now works in-game, but there's still work needed to polish the algorithm and creating a proper lookup for jump types as currently only 1 jump type is supported.

src/naveditor/Editor.cpp

@@ -353,6 +353,12 @@ void Editor::handleUpdate(const float dt)
 	updateToolStates(dt);
 }
 
+void Editor::buildTraverseLinks()
+{
+	if (!m_navMesh) return;
+	dtCreateTraverseLinks(m_navMesh);
+}
+
 void Editor::buildStaticPathingData()
 {
 	if (!m_navMesh) return;

src/naveditor/Editor_TileMesh.cpp

@@ -145,6 +145,7 @@ public:
 			else
 				m_editor->buildTile(m_hitPos);
 
+			m_editor->buildTraverseLinks();
 			m_editor->buildStaticPathingData();
 		}
 	}
@@ -597,6 +598,7 @@ void Editor_TileMesh::buildAllTiles()
 		}
 	}
 
+	buildTraverseLinks();
 	buildStaticPathingData();
 	
 	// Start the build process.	

src/naveditor/include/Editor.h

@@ -239,6 +239,7 @@ public:
 	void resetCommonSettings();
 	void handleCommonSettings();
 
+	void buildTraverseLinks();
 	void buildStaticPathingData();
 
 private:

src/thirdparty/recast/Detour/Include/DetourNavMesh.h

@@ -415,6 +415,10 @@ struct dtMeshHeader
 /// @ingroup detour
 struct dtMeshTile
 {
+public:
+	unsigned int allocLink();
+	void freeLink(unsigned int link);
+
 	unsigned int salt;					///Counter describing modifications to the tile.
 
 	unsigned int linksFreeList;			///Index to the next free link.

src/thirdparty/recast/Detour/Include/DetourNavMeshBuilder.h

@@ -182,6 +182,12 @@ private:
 /// @return True if the disjoint set data was successfully created.
 bool dtCreateDisjointPolyGroups(dtNavMesh* nav, dtDisjointSet& disjoint);
 
+/// Builds navigation mesh traverse links from the provided navmesh.
+/// @ingroup detour
+///  @param[in]		nav			The navigation mesh to use.
+/// @return True if the traverse links were successfully created.
+bool dtCreateTraverseLinks(dtNavMesh* nav);
+
 /// Builds navigation mesh static traversal table from the provided navmesh.
 /// @ingroup detour
 ///  @param[in]		nav			The navigation mesh to use.

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

@@ -115,19 +115,19 @@ inline int computeTileHash(int x, int y, const int mask)
 	return (int)(n & mask);
 }
 
-inline unsigned int allocLink(dtMeshTile* tile)
+unsigned int dtMeshTile::allocLink()
 {
-	if (tile->linksFreeList == DT_NULL_LINK)
+	if (linksFreeList == DT_NULL_LINK)
 		return DT_NULL_LINK;
-	unsigned int link = tile->linksFreeList;
-	tile->linksFreeList = tile->links[link].next;
+	unsigned int link = linksFreeList;
+	linksFreeList = links[link].next;
 	return link;
 }
 
-inline void freeLink(dtMeshTile* tile, unsigned int link)
+void dtMeshTile::freeLink(unsigned int link)
 {
-	tile->links[link].next = tile->linksFreeList;
-	tile->linksFreeList = link;
+	links[link].next = linksFreeList;
+	linksFreeList = link;
 }
 
 int dtCalcTraversalTableCellIndex(const int numPolyGroups,
@@ -409,7 +409,7 @@ void dtNavMesh::unconnectLinks(dtMeshTile* tile, dtMeshTile* target)
 					poly->firstLink = nj;
 				else
 					tile->links[pj].next = nj;
-				freeLink(tile, j);
+				tile->freeLink(j);
 				j = nj;
 			}
 			else
@@ -453,7 +453,7 @@ void dtNavMesh::connectExtLinks(dtMeshTile* tile, dtMeshTile* target, int side)
 			int nnei = findConnectingPolys(va,vb, target, rdOppositeTile(dir), nei,neia,4);
 			for (int k = 0; k < nnei; ++k)
 			{
-				unsigned int idx = allocLink(tile);
+				unsigned int idx = tile->allocLink();
 				if (idx != DT_NULL_LINK)
 				{
 					dtLink* link = &tile->links[idx];
@@ -528,7 +528,7 @@ void dtNavMesh::connectExtOffMeshLinks(dtMeshTile* tile, dtMeshTile* target, int
 		rdVcopy(v, nearestPt);
 
 		// Link off-mesh connection to target poly.
-		unsigned int idx = allocLink(target);
+		unsigned int idx = target->allocLink();
 		dtLink* link = nullptr;
 		if (idx != DT_NULL_LINK)
 		{
@@ -550,7 +550,7 @@ void dtNavMesh::connectExtOffMeshLinks(dtMeshTile* tile, dtMeshTile* target, int
 		dtLink* tlink = nullptr;
 		if (targetCon->flags & DT_OFFMESH_CON_BIDIR)
 		{
-			tidx = allocLink(tile);
+			tidx = tile->allocLink();
 			if (tidx != DT_NULL_LINK)
 			{
 				const unsigned short landPolyIdx = (unsigned short)decodePolyIdPoly(ref);
@@ -611,7 +611,7 @@ void dtNavMesh::connectIntLinks(dtMeshTile* tile)
 			// Skip hard and non-internal edges.
 			if (poly->neis[j] == 0 || (poly->neis[j] & DT_EXT_LINK)) continue;
 
-			unsigned int idx = allocLink(tile);
+			unsigned int idx = tile->allocLink();
 			if (idx != DT_NULL_LINK)
 			{
 				dtLink* link = &tile->links[idx];
@@ -657,7 +657,7 @@ void dtNavMesh::baseOffMeshLinks(dtMeshTile* tile)
 		rdVcopy(v, nearestPt);
 
 		// Link off-mesh connection to target poly.
-		unsigned int idx = allocLink(tile);
+		unsigned int idx = tile->allocLink();
 		if (idx != DT_NULL_LINK)
 		{
 			dtLink* link = &tile->links[idx];
@@ -674,7 +674,7 @@ void dtNavMesh::baseOffMeshLinks(dtMeshTile* tile)
 		}
 
 		// Start end-point is always connect back to off-mesh connection. 
-		unsigned int tidx = allocLink(tile);
+		unsigned int tidx = tile->allocLink();
 		if (tidx != DT_NULL_LINK)
 		{
 			const unsigned short landPolyIdx = (unsigned short)decodePolyIdPoly(ref);

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

@@ -461,6 +461,103 @@ bool dtCreateDisjointPolyGroups(dtNavMesh* nav, dtDisjointSet& disjoint)
 	return true;
 }
 
+// TODO: create lookup table and look for distance + slope to determine the
+// correct jumpType.
+// TODO: make sure we don't generate duplicate pairs of jump types between
+// 2 polygons.
+static void connectTileTraverseLinks(dtNavMesh* const nav, dtMeshTile* const tile)
+{
+	for (int i = 0; i < tile->header->polyCount; ++i)
+	{
+		dtPoly* const startPoly = &tile->polys[i];
+
+		for (int j = 0; j < startPoly->vertCount; ++j)
+		{
+			// Hard edges only!
+			if (startPoly->neis[j] != 0)
+				continue;
+
+			// Polygon 1 edge
+			const float* const startPolySpos = &tile->verts[startPoly->verts[j] * 3];
+			const float* const startPolyEpos = &tile->verts[startPoly->verts[(j + 1) % startPoly->vertCount] * 3];
+
+			for (int k = 0; k < tile->header->polyCount; ++k)
+			{
+				if (i == k) continue; // Skip self
+
+				dtPoly* const endPoly = &tile->polys[k];
+
+				for (int m = 0; m < endPoly->vertCount; ++m)
+				{
+					// Hard edges only!
+					if (endPoly->neis[m] != 0)
+						continue;
+
+					// Polygon 2 edge
+					const float* const endPolySpos = &tile->verts[endPoly->verts[m] * 3];
+					const float* const endPolyEpos = &tile->verts[endPoly->verts[(m + 1) % endPoly->vertCount] * 3];
+
+					// TODO: calculate edge midpoint first !!!
+					const unsigned char dist1 = dtCalcLinkDistance(startPolySpos, endPolyEpos);
+					const unsigned char dist2 = dtCalcLinkDistance(startPolyEpos, endPolySpos);
+
+					// TODO: needs lookup table for distance !!!
+					if ((dist1 >= 10 && dist1 <= 30) && (dist2 >= 10 && dist2 <= 30))
+					{
+						const unsigned int idx = tile->allocLink();
+
+						if (idx == DT_NULL_LINK) // TODO: should move on to next tile.
+							continue;
+
+						dtLink* const forwardLink = &tile->links[idx];
+
+						forwardLink->ref = nav->getPolyRefBase(tile) | (unsigned int)k;
+						forwardLink->edge = (unsigned char)j;
+						forwardLink->side = 0xFF;
+						forwardLink->next = startPoly->firstLink;
+						startPoly->firstLink = idx;
+						forwardLink->traverseType = 1;
+						forwardLink->traverseDist = dist1;
+
+						const unsigned int tidx = tile->allocLink();
+
+						if (tidx == DT_NULL_LINK) // TODO: should move on to next tile.
+							continue;
+
+						dtLink* const reverseLink = &tile->links[tidx];
+
+						reverseLink->ref = nav->getPolyRefBase(tile) | (unsigned int)i;
+						reverseLink->edge = (unsigned char)m;
+						reverseLink->side = 0xFF;
+						reverseLink->next = endPoly->firstLink;
+						endPoly->firstLink = tidx;
+						reverseLink->traverseType = 1;
+						reverseLink->traverseDist = dist2;
+
+						forwardLink->reverseLink = (unsigned short)tidx;
+						reverseLink->reverseLink = (unsigned short)idx;
+					}
+				}
+			}
+		}
+	}
+}
+
+bool dtCreateTraverseLinks(dtNavMesh* nav)
+{
+	rdAssert(nav);
+
+	for (int i = 0; i < nav->getMaxTiles(); i++)
+	{
+		dtMeshTile* tile = nav->getTile(i);
+		if (!tile->header) continue;
+
+		connectTileTraverseLinks(nav, tile);
+	}
+
+	return true;
+}
+
 // todo(amos): remove param 'tableCount' and make struct 'dtTraversalTableCreateParams'
 bool dtCreateTraversalTableData(dtNavMesh* nav, const dtDisjointSet& disjoint, const int tableCount)
 {
@@ -877,18 +974,6 @@ bool dtCreateNavMeshData(dtNavMeshCreateParams* params, unsigned char** outData,
 		}
 	}
 	
-#if DT_NAVMESH_SET_VERSION >= 8
-	// Polygon cells.
-	for (int i = 0; i < (int)cellItems.size(); i++)
-	{
-		const CellItem& cellItem = cellItems[i];
-		dtCell& cell = navCells[i];
-
-		rdVcopy(cell.pos, cellItem.pos);
-		cell.polyIndex = cellItem.polyIndex;
-	}
-#endif
-	
 	// Store polygons
 	// Mesh polys
 	const unsigned short* src = params->polys;
@@ -1041,6 +1126,18 @@ bool dtCreateNavMeshData(dtNavMeshCreateParams* params, unsigned char** outData,
 		}
 	}
 
+#if DT_NAVMESH_SET_VERSION >= 8
+	// Polygon cells.
+	for (int i = 0; i < (int)cellItems.size(); i++)
+	{
+		const CellItem& cellItem = cellItems[i];
+		dtCell& cell = navCells[i];
+
+		rdVcopy(cell.pos, cellItem.pos);
+		cell.polyIndex = cellItem.polyIndex;
+	}
+#endif
+
 	rdFree(offMeshConClass);
 
 	*outData = data;