From 1024f50c0c81a9f2d0f546d80050a5a96e4d2786 Mon Sep 17 00:00:00 2001
From: Kawe Mazidjatari <48657826+Mauler125@users.noreply.github.com>
Date: Tue, 20 Aug 2024 22:22:43 +0200
Subject: [PATCH] Recast: only link 2 polygons with the same traverse type once

Major improvement to generated navmesh, avoids duplicated links.
---
 src/naveditor/Editor.cpp       | 21 +++++++++++++++++----
 src/naveditor/include/Editor.h | 26 ++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/src/naveditor/Editor.cpp b/src/naveditor/Editor.cpp
index 22a43b48..42a9884e 100644
--- a/src/naveditor/Editor.cpp
+++ b/src/naveditor/Editor.cpp
@@ -762,10 +762,6 @@ static bool traverseLinkInLOS(const InputGeom* geom, const float* lowPos, const
 	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.
 void Editor::connectTileTraverseLinks(dtMeshTile* const baseTile, const bool linkToNeighbor)
 {
 	// If we link to the same tile, we need at least 2 links.
@@ -919,6 +915,17 @@ void Editor::connectTileTraverseLinks(dtMeshTile* const baseTile, const bool lin
 								continue;
 						}
 
+						const TraverseLinkPolyPair linkedPolyPair(basePoly, landPoly);
+						auto linkedIt = m_traverseLinkPolyMap.find(linkedPolyPair);
+
+						bool traverseLinkFound = false;
+
+						if (linkedIt != m_traverseLinkPolyMap.end())
+							traverseLinkFound = true;
+
+						// These 2 polygons are already linked with the same traverse type.
+						if (traverseLinkFound && (rdBitCellBit(traverseType) & linkedIt->second))
+							continue;
 
 						const bool basePolyHigher = basePolyEdgeMid[2] > landPolyEdgeMid[2];
 						float* const lowerEdgeMid = basePolyHigher ? landPolyEdgeMid : basePolyEdgeMid;
@@ -981,6 +988,11 @@ void Editor::connectTileTraverseLinks(dtMeshTile* const baseTile, const bool lin
 						reverseLink->traverseType = (unsigned char)traverseType;
 						reverseLink->traverseDist = quantDist;
 						reverseLink->reverseLink = (unsigned short)forwardIdx;
+
+						if (traverseLinkFound)
+							linkedIt->second |= 1 << traverseType;
+						else
+							m_traverseLinkPolyMap.emplace(linkedPolyPair, 1 << traverseType);
 					}
 				}
 			}
@@ -1013,6 +1025,7 @@ bool Editor::createTraverseLinks()
 		connectTileTraverseLinks(baseTile, false);
 	}
 
+	m_traverseLinkPolyMap.clear();
 	return true;
 }
 
diff --git a/src/naveditor/include/Editor.h b/src/naveditor/include/Editor.h
index 91d3ee67..b05c0793 100644
--- a/src/naveditor/include/Editor.h
+++ b/src/naveditor/include/Editor.h
@@ -192,6 +192,31 @@ enum EditorPolyFlags
 	EDITOR_POLYFLAGS_ALL				= 0xffff	// All abilities.
 };
 
+struct TraverseLinkPolyPair
+{
+	TraverseLinkPolyPair(const dtPoly* p1, const dtPoly* p2)
+	{
+		if (p1 > p2)
+			rdSwap(p1, p2);
+
+		poly1 = p1;
+		poly2 = p2;
+	}
+
+	bool operator<(const TraverseLinkPolyPair& other) const
+	{
+		if (poly1 < other.poly1)
+			return true;
+		if (poly1 > other.poly1)
+			return false;
+
+		return poly2 < other.poly2;
+	}
+
+	const dtPoly* poly1;
+	const dtPoly* poly2;
+};
+
 class EditorDebugDraw : public DebugDrawGL
 {
 public:
@@ -274,6 +299,7 @@ protected:
 	
 	BuildContext* m_ctx;
 	dtDisjointSet m_djs[DT_MAX_TRAVERSE_TABLES];
+	std::map<TraverseLinkPolyPair, unsigned int> m_traverseLinkPolyMap;
 
 	EditorDebugDraw m_dd;
 	unsigned int m_navMeshDrawFlags;