Reject empty quad tree nodes at the cell level without land data

apps/openmw/mwrender/terrainstorage.cpp

@@ -22,6 +22,15 @@ namespace MWRender
         mResourceSystem->removeResourceManager(mLandManager.get());
     }
 
+    bool TerrainStorage::hasData(int cellX, int cellY)
+    {
+        const MWWorld::ESMStore &esmStore =
+             MWBase::Environment::get().getWorld()->getStore();
+
+        const ESM::Land* land = esmStore.get<ESM::Land>().search(cellX, cellY);
+        return land != nullptr;
+    }
+
     void TerrainStorage::getBounds(float& minX, float& maxX, float& minY, float& maxY)
     {
         minX = 0, minY = 0, maxX = 0, maxY = 0;

apps/openmw/mwrender/terrainstorage.hpp

@@ -23,6 +23,8 @@ namespace MWRender
         virtual osg::ref_ptr<const ESMTerrain::LandObject> getLand (int cellX, int cellY);
         virtual const ESM::LandTexture* getLandTexture(int index, short plugin);
 
+        virtual bool hasData(int cellX, int cellY) override;
+
         /// Get bounds of the whole terrain in cell units
         virtual void getBounds(float& minX, float& maxX, float& minY, float& maxY);
 

components/terrain/quadtreeworld.cpp

@@ -184,6 +184,11 @@ public:
             return node;
         }
 
+        // Do not add child nodes for default cells without data.
+        // size = 1 means that the single shape covers the whole cell.
+        if (node->getSize() == 1 && !mStorage->hasData(center.x()-0.5, center.y()-0.5))
+            return node;
+
         if (node->getSize() <= mMinSize)
         {
             // We arrived at a leaf

components/terrain/storage.hpp

@@ -28,6 +28,14 @@ namespace Terrain
         /// Get bounds of the whole terrain in cell units
         virtual void getBounds(float& minX, float& maxX, float& minY, float& maxY) = 0;
 
+        /// Return true if there is land data for this cell
+        /// May be overriden for a faster implementation
+        virtual bool hasData(int cellX, int cellY)
+        {
+            float dummy;
+            return getMinMaxHeights(1, osg::Vec2f(cellX+0.5, cellY+0.5), dummy, dummy);
+        }
+
         /// Get the minimum and maximum heights of a terrain region.
         /// @note Will only be called for chunks with size = minBatchSize, i.e. leafs of the quad tree.
         ///        Larger chunks can simply merge AABB of children.