Add LOD stitches

components/terrain/chunkmanager.cpp

@@ -31,10 +31,10 @@ ChunkManager::ChunkManager(Storage *storage, Resource::SceneManager *sceneMgr, T
 
 }
 
-osg::ref_ptr<osg::Node> ChunkManager::getChunk(float size, const osg::Vec2f &center, int lod)
+osg::ref_ptr<osg::Node> ChunkManager::getChunk(float size, const osg::Vec2f &center, int lod, unsigned int lodFlags)
 {
     std::ostringstream stream;
-    stream << size << " " << center.x() << " " << center.y();
+    stream << size << " " << center.x() << " " << center.y() << " " << lod << " " << lodFlags;
     std::string id = stream.str();
 
     osg::ref_ptr<osg::Object> obj = mCache->getRefFromObjectCache(id);
@@ -42,7 +42,7 @@ osg::ref_ptr<osg::Node> ChunkManager::getChunk(float size, const osg::Vec2f &cen
         return obj->asNode();
     else
     {
-        osg::ref_ptr<osg::Node> node = createChunk(size, center, lod);
+        osg::ref_ptr<osg::Node> node = createChunk(size, center, lod, lodFlags);
         mCache->addEntryToObjectCache(id, node.get());
         return node;
     }
@@ -156,7 +156,7 @@ std::vector<osg::ref_ptr<osg::StateSet> > ChunkManager::createPasses(float chunk
                                      mSceneManager->getClampLighting(), &mSceneManager->getShaderManager(), layers, blendmapTextures, blendmapScale, blendmapScale);
 }
 
-osg::ref_ptr<osg::Node> ChunkManager::createChunk(float chunkSize, const osg::Vec2f &chunkCenter, int lod)
+osg::ref_ptr<osg::Node> ChunkManager::createChunk(float chunkSize, const osg::Vec2f &chunkCenter, int lod, unsigned int lodFlags)
 {
     osg::Vec2f worldCenter = chunkCenter*mStorage->getCellWorldSize();
     osg::ref_ptr<SceneUtil::PositionAttitudeTransform> transform (new SceneUtil::PositionAttitudeTransform);
@@ -182,7 +182,7 @@ osg::ref_ptr<osg::Node> ChunkManager::createChunk(float chunkSize, const osg::Ve
 
     unsigned int numVerts = (mStorage->getCellVertices()-1) * chunkSize / (1 << lod) + 1;
 
-    geometry->addPrimitiveSet(mBufferCache.getIndexBuffer(numVerts, 0));
+    geometry->addPrimitiveSet(mBufferCache.getIndexBuffer(numVerts, lodFlags));
 
     geometry->getBound();
 

components/terrain/chunkmanager.hpp

@@ -34,12 +34,12 @@ namespace Terrain
     public:
         ChunkManager(Storage* storage, Resource::SceneManager* sceneMgr, TextureManager* textureManager, CompositeMapRenderer* renderer);
 
-        osg::ref_ptr<osg::Node> getChunk(float size, const osg::Vec2f& center, int lod);
+        osg::ref_ptr<osg::Node> getChunk(float size, const osg::Vec2f& center, int lod, unsigned int lodFlags);
 
         virtual void reportStats(unsigned int frameNumber, osg::Stats* stats) const;
 
     private:
-        osg::ref_ptr<osg::Node> createChunk(float size, const osg::Vec2f& center, int lod);
+        osg::ref_ptr<osg::Node> createChunk(float size, const osg::Vec2f& center, int lod, unsigned int lodFlags);
 
         osg::ref_ptr<osg::Group> createCompositeMapRTT(osg::ref_ptr<osg::Texture2D>& texture);
 

components/terrain/quadtreenode.cpp

@@ -80,6 +80,11 @@ QuadTreeNode *QuadTreeNode::getChild(unsigned int i)
     return static_cast<QuadTreeNode*>(Group::getChild(i));
 }
 
+QuadTreeNode *QuadTreeNode::getNeighbour(Direction dir)
+{
+    return mNeighbours[dir];
+}
+
 void QuadTreeNode::initNeighbours()
 {
     for (int i=0; i<4; ++i)

components/terrain/quadtreeworld.cpp

@@ -255,6 +255,34 @@ void traverse(QuadTreeNode* node, ViewData* vd, osgUtil::CullVisitor* cv, bool v
     }
 }
 
+unsigned int getLodFlags(QuadTreeNode* node, int ourLod, ViewData* vd)
+{
+    unsigned int lodFlags = 0;
+    for (unsigned int i=0; i<4; ++i)
+    {
+        QuadTreeNode* neighbour = node->getNeighbour(static_cast<Direction>(i));
+
+        // If the neighbour isn't currently rendering itself,
+        // go up until we find one. NOTE: We don't need to go down,
+        // because in that case neighbour's detail would be higher than
+        // our detail and the neighbour would handle stitching by itself.
+        while (neighbour && !vd->contains(neighbour))
+            neighbour = neighbour->getParent();
+        int lod = 0;
+        if (neighbour)
+            lod = Log2(int(neighbour->getSize()));
+
+        if (lod <= ourLod) // We only need to worry about neighbours less detailed than we are -
+            lod = 0;         // neighbours with more detail will do the stitching themselves
+        // Use 4 bits for each LOD delta
+        if (lod > 0)
+        {
+            lodFlags |= static_cast<unsigned int>(lod - ourLod) << (4*i);
+        }
+    }
+    return lodFlags;
+}
+
 void QuadTreeWorld::accept(osg::NodeVisitor &nv)
 {
     if (nv.getVisitorType() != osg::NodeVisitor::CULL_VISITOR)// && nv.getVisitorType() != osg::NodeVisitor::INTERSECTION_VISITOR)
@@ -275,8 +303,9 @@ void QuadTreeWorld::accept(osg::NodeVisitor &nv)
         ViewData::Entry& entry = vd->getEntry(i);
         if (!entry.mRenderingNode)
         {
-            int lod = Log2(int(entry.mNode->getSize()));
-            entry.mRenderingNode = mChunkManager->getChunk(entry.mNode->getSize(), entry.mNode->getCenter(), lod);
+            int ourLod = Log2(int(entry.mNode->getSize()));
+            unsigned int lodFlags = getLodFlags(entry.mNode, ourLod, vd);
+            entry.mRenderingNode = mChunkManager->getChunk(entry.mNode->getSize(), entry.mNode->getCenter(), ourLod, lodFlags);
         }
 
         if (entry.mVisible)

components/terrain/terraingrid.cpp

@@ -47,7 +47,7 @@ osg::ref_ptr<osg::Node> TerrainGrid::buildTerrain (osg::Group* parent, float chu
     }
     else
     {
-        osg::ref_ptr<osg::Node> node = mChunkManager->getChunk(chunkSize, chunkCenter, 0);
+        osg::ref_ptr<osg::Node> node = mChunkManager->getChunk(chunkSize, chunkCenter, 0, 0);
         if (!node)
             return NULL;
         if (parent)

components/terrain/viewdata.cpp

@@ -54,6 +54,14 @@ void ViewData::clear()
     mFrameLastUsed = 0;
 }
 
+bool ViewData::contains(QuadTreeNode *node)
+{
+    for (unsigned int i=0; i<mNumEntries; ++i)
+        if (mEntries[i].mNode == node)
+            return true;
+    return false;
+}
+
 ViewData::Entry::Entry()
     : mNode(NULL)
     , mVisible(true)

components/terrain/viewdata.hpp

@@ -22,6 +22,8 @@ namespace Terrain
 
         void clear();
 
+        bool contains(QuadTreeNode* node);
+
         struct Entry
         {
             Entry();