Add settings option to set max number of polygons per navmesh tile

apps/openmw/mwworld/worldimp.cpp

@@ -211,6 +211,7 @@ namespace MWWorld
         navigatorSettings.mSwimHeightScale = mSwimHeightScale;
         navigatorSettings.mMaxEdgeLen = Settings::Manager::getInt("max edge len", "Navigator");
         navigatorSettings.mMaxNavMeshQueryNodes = Settings::Manager::getInt("max nav mesh query nodes", "Navigator");
+        navigatorSettings.mMaxPolys = Settings::Manager::getInt("max polygons per tile", "Navigator");
         navigatorSettings.mMaxVertsPerPoly = Settings::Manager::getInt("max verts per poly", "Navigator");
         navigatorSettings.mRegionMergeSize = Settings::Manager::getInt("region merge size", "Navigator");
         navigatorSettings.mRegionMinSize = Settings::Manager::getInt("region min size", "Navigator");

apps/openmw_test_suite/detournavigator/navigator.cpp

@@ -60,6 +60,7 @@ namespace
             mSettings.mMaxPolygonPathSize = 1024;
             mSettings.mMaxSmoothPathSize = 1024;
             mSettings.mTrianglesPerChunk = 256;
+            mSettings.mMaxPolys = 4096;
             mNavigator.reset(new Navigator(mSettings));
         }
     };

components/detournavigator/makenavmesh.cpp

@@ -456,6 +456,15 @@ namespace
         else
             return UpdateNavMeshStatus::ignore;
     }
+
+    template <class T>
+    unsigned long getMinValuableBitsNumber(const T value)
+    {
+        unsigned long power = 0;
+        while (power < sizeof(T) * 8 && (static_cast<T>(1) << power) < value)
+            ++power;
+        return power;
+    }
 }
 
 namespace DetourNavigator
@@ -464,17 +473,20 @@ namespace DetourNavigator
     {
         // Max tiles and max polys affect how the tile IDs are caculated.
         // There are 22 bits available for identifying a tile and a polygon.
-        const auto tileBits = 10;
-        const auto polyBits = 22 - tileBits;
-        const auto maxTiles = 1 << tileBits;
-        const auto maxPolysPerTile = 1 << polyBits;
+        const int polysAndTilesBits = 22;
+        const auto polysBits = getMinValuableBitsNumber(settings.mMaxPolys);
+
+        if (polysBits >= polysAndTilesBits)
+            throw InvalidArgument("Too many polygons per tile");
+
+        const auto tilesBits = polysAndTilesBits - polysBits;
 
         dtNavMeshParams params;
         std::fill_n(params.orig, 3, 0.0f);
         params.tileWidth = settings.mTileSize * settings.mCellSize;
         params.tileHeight = settings.mTileSize * settings.mCellSize;
-        params.maxTiles = maxTiles;
-        params.maxPolys = maxPolysPerTile;
+        params.maxTiles = 1 << tilesBits;
+        params.maxPolys = 1 << polysBits;
 
         NavMeshPtr navMesh(dtAllocNavMesh(), &dtFreeNavMesh);
         const auto status = navMesh->init(&params);

components/detournavigator/settings.hpp

@@ -23,6 +23,7 @@ namespace DetourNavigator
         int mBorderSize;
         int mMaxEdgeLen;
         int mMaxNavMeshQueryNodes;
+        int mMaxPolys;
         int mMaxVertsPerPoly;
         int mRegionMergeSize;
         int mRegionMinSize;

files/settings-default.cfg

@@ -576,6 +576,11 @@ max edge len = 12
 # Maximum number of search nodes. (0 < value <= 65535)
 max nav mesh query nodes = 2048
 
+# Maximum number of polygons per navmesh tile (value = 2^n, 0 < n < 22). Maximum number of navmesh tiles depends on
+# this value. 22 bits is a limit to store both tile identifier and polygon identifier (tiles = 2^(22 - log2(polygons))).
+# See recastnavigation for more details.
+max polygons per tile = 4096
+
 # The maximum number of vertices allowed for polygons generated during the contour to polygon conversion process. (value >= 3)
 max verts per poly = 6