Prioritise NavMesh jobs first to remove and last to add

When player move fast enough, tiles update for specific area square
couldn't catch player move. Tiles to be removed are left in the queue
with lower priority then tiles to be added which are nearest to player.
This can lead to overflow for amount of tiles. So we try to do remove
first. But we detect change type approximately using mixed change type,
because even if we do it precise, change type could change while job
is in queue.

components/detournavigator/asyncnavmeshupdater.cpp

@@ -9,16 +9,22 @@
 
 namespace
 {
+    using DetourNavigator::ChangeType;
     using DetourNavigator::TilePosition;
 
-    int getDistance(const TilePosition& lhs, const TilePosition& rhs)
+    int getManhattanDistance(const TilePosition& lhs, const TilePosition& rhs)
     {
         return std::abs(lhs.x() - rhs.x()) + std::abs(lhs.y() - rhs.y());
     }
 
-    std::pair<int, int> makePriority(const TilePosition& changedTile, const TilePosition& playerTile)
+    std::tuple<ChangeType, int, int> makePriority(const TilePosition& position, const ChangeType changeType,
+                                                    const TilePosition& playerTile)
     {
-        return std::make_pair(getDistance(changedTile, playerTile), getDistance(changedTile, TilePosition {0, 0}));
+        return std::make_tuple(
+            changeType,
+            getManhattanDistance(position, playerTile),
+            getManhattanDistance(position, TilePosition {0, 0})
+        );
     }
 }
 
@@ -60,7 +66,7 @@ namespace DetourNavigator
 
     void AsyncNavMeshUpdater::post(const osg::Vec3f& agentHalfExtents,
         const std::shared_ptr<NavMeshCacheItem>& navMeshCacheItem, const TilePosition& playerTile,
-        const std::set<TilePosition>& changedTiles)
+        const std::map<TilePosition, ChangeType>& changedTiles)
     {
         log("post jobs playerTile=", playerTile);
 
@@ -73,9 +79,9 @@ namespace DetourNavigator
 
         for (const auto& changedTile : changedTiles)
         {
-            if (mPushed[agentHalfExtents].insert(changedTile).second)
-                mJobs.push(Job {agentHalfExtents, navMeshCacheItem, changedTile,
-                                makePriority(changedTile, playerTile)});
+            if (mPushed[agentHalfExtents].insert(changedTile.first).second)
+                mJobs.push(Job {agentHalfExtents, navMeshCacheItem, changedTile.first,
+                                makePriority(changedTile.first, changedTile.second, playerTile)});
         }
 
         log("posted ", mJobs.size(), " jobs");

components/detournavigator/asyncnavmeshupdater.hpp

@@ -22,6 +22,13 @@ class dtNavMesh;
 
 namespace DetourNavigator
 {
+    enum class ChangeType
+    {
+        remove = 0,
+        mixed = 1,
+        add = 2,
+    };
+
     class AsyncNavMeshUpdater
     {
     public:
@@ -29,7 +36,7 @@ namespace DetourNavigator
         ~AsyncNavMeshUpdater();
 
         void post(const osg::Vec3f& agentHalfExtents, const std::shared_ptr<NavMeshCacheItem>& mNavMeshCacheItem,
-            const TilePosition& playerTile, const std::set<TilePosition>& changedTiles);
+            const TilePosition& playerTile, const std::map<TilePosition, ChangeType>& changedTiles);
 
         void wait();
 
@@ -39,7 +46,7 @@ namespace DetourNavigator
             osg::Vec3f mAgentHalfExtents;
             std::shared_ptr<NavMeshCacheItem> mNavMeshCacheItem;
             TilePosition mChangedTile;
-            std::pair<int, int> mPriority;
+            std::tuple<ChangeType, int, int> mPriority;
 
             friend inline bool operator <(const Job& lhs, const Job& rhs)
             {

components/detournavigator/navmeshmanager.cpp

@@ -13,6 +13,16 @@
 
 #include <iostream>
 
+namespace
+{
+    using DetourNavigator::ChangeType;
+
+    ChangeType addChangeType(const ChangeType current, const ChangeType add)
+    {
+        return current == add ? current : ChangeType::mixed;
+    }
+}
+
 namespace DetourNavigator
 {
     NavMeshManager::NavMeshManager(const Settings& settings)
@@ -26,7 +36,7 @@ namespace DetourNavigator
     {
         if (!mRecastMeshManager.addObject(id, shape, transform))
             return false;
-        addChangedTiles(shape, transform);
+        addChangedTiles(shape, transform, ChangeType::add);
         return true;
     }
 
@@ -34,7 +44,7 @@ namespace DetourNavigator
     {
         if (!mRecastMeshManager.updateObject(id, transform))
             return false;
-        addChangedTiles(shape, transform);
+        addChangedTiles(shape, transform, ChangeType::mixed);
         return true;
     }
 
@@ -43,7 +53,7 @@ namespace DetourNavigator
         const auto object = mRecastMeshManager.removeObject(id);
         if (!object)
             return false;
-        addChangedTiles(object->mShape, object->mTransform);
+        addChangedTiles(object->mShape, object->mTransform, ChangeType::remove);
         return true;
     }
 
@@ -72,7 +82,7 @@ namespace DetourNavigator
             return;
         mLastRecastMeshManagerRevision = mRecastMeshManager.getRevision();
         mPlayerTile = playerTile;
-        std::set<TilePosition> tilesToPost;
+        std::map<TilePosition, ChangeType> tilesToPost;
         const auto& cached = getCached(agentHalfExtents);
         const auto changedTiles = mChangedTiles.find(agentHalfExtents);
         {
@@ -80,10 +90,16 @@ namespace DetourNavigator
             if (changedTiles != mChangedTiles.end())
             {
                 for (const auto& tile : changedTiles->second)
-                    if (locked->getTileAt(tile.x(), tile.y(), 0))
-                        tilesToPost.insert(tile);
+                    if (locked->getTileAt(tile.first.x(), tile.first.y(), 0))
+                    {
+                        auto tileToPost = tilesToPost.find(tile.first);
+                        if (tileToPost == tilesToPost.end())
+                            tilesToPost.insert(tile);
+                        else
+                            tileToPost->second = addChangeType(tileToPost->second, tile.second);
+                    }
                 for (const auto& tile : tilesToPost)
-                    changedTiles->second.erase(tile);
+                    changedTiles->second.erase(tile.first);
                 if (changedTiles->second.empty())
                     mChangedTiles.erase(changedTiles);
             }
@@ -94,8 +110,10 @@ namespace DetourNavigator
                     return;
                 const auto shouldAdd = shouldAddTile(tile, playerTile, maxTiles);
                 const auto presentInNavMesh = bool(locked->getTileAt(tile.x(), tile.y(), 0));
-                if ((shouldAdd && !presentInNavMesh) || (!shouldAdd && presentInNavMesh))
-                    tilesToPost.insert(tile);
+                if (shouldAdd && !presentInNavMesh)
+                    tilesToPost.insert(std::make_pair(tile, ChangeType::add));
+                else if (!shouldAdd && presentInNavMesh)
+                    tilesToPost.insert(std::make_pair(tile, ChangeType::mixed));
             });
         }
         mAsyncNavMeshUpdater.post(agentHalfExtents, cached, playerTile, tilesToPost);
@@ -120,12 +138,20 @@ namespace DetourNavigator
         return mCache;
     }
 
-    void NavMeshManager::addChangedTiles(const btCollisionShape& shape, const btTransform& transform)
+    void NavMeshManager::addChangedTiles(const btCollisionShape& shape, const btTransform& transform,
+                                         const ChangeType changeType)
     {
         getTilesPositions(shape, transform, mSettings, [&] (const TilePosition& v) {
             for (const auto& cached : mCache)
                 if (cached.second)
-                    mChangedTiles[cached.first].insert(v);
+                {
+                    auto& tiles = mChangedTiles[cached.first];
+                    auto tile = tiles.find(v);
+                    if (tile == tiles.end())
+                        tiles.insert(std::make_pair(v, changeType));
+                    else
+                        tile->second = addChangeType(tile->second, changeType);
+                }
         });
     }
 

components/detournavigator/navmeshmanager.hpp

@@ -45,13 +45,13 @@ namespace DetourNavigator
         const Settings& mSettings;
         TileCachedRecastMeshManager mRecastMeshManager;
         std::map<osg::Vec3f, std::shared_ptr<NavMeshCacheItem>> mCache;
-        std::map<osg::Vec3f, std::set<TilePosition>> mChangedTiles;
+        std::map<osg::Vec3f, std::map<TilePosition, ChangeType>> mChangedTiles;
         AsyncNavMeshUpdater mAsyncNavMeshUpdater;
         std::size_t mGenerationCounter = 0;
         boost::optional<TilePosition> mPlayerTile;
         std::size_t mLastRecastMeshManagerRevision = 0;
 
-        void addChangedTiles(const btCollisionShape& shape, const btTransform& transform);
+        void addChangedTiles(const btCollisionShape& shape, const btTransform& transform, const ChangeType changeType);
 
         const std::shared_ptr<NavMeshCacheItem>& getCached(const osg::Vec3f& agentHalfExtents) const;
     };