Improve const-correctness in BulletShapeManager

Sadly, two const_cast's are needed to work around Bullet API quirks.

components/resource/bulletshape.cpp

@@ -45,11 +45,11 @@ void BulletShape::deleteShape(btCollisionShape* shape)
     }
 }
 
-btCollisionShape* BulletShape::duplicateCollisionShape(btCollisionShape *shape) const
+btCollisionShape* BulletShape::duplicateCollisionShape(const btCollisionShape *shape) const
 {
     if(shape->isCompound())
     {
-        btCompoundShape *comp = static_cast<btCompoundShape*>(shape);
+        const btCompoundShape *comp = static_cast<const btCompoundShape*>(shape);
         btCompoundShape *newShape = new btCompoundShape;
 
         int numShapes = comp->getNumChildShapes();
@@ -63,29 +63,27 @@ btCollisionShape* BulletShape::duplicateCollisionShape(btCollisionShape *shape)
         return newShape;
     }
 
-    if(btBvhTriangleMeshShape* trishape = dynamic_cast<btBvhTriangleMeshShape*>(shape))
+    if(const btBvhTriangleMeshShape* trishape = dynamic_cast<const btBvhTriangleMeshShape*>(shape))
     {
 #if BT_BULLET_VERSION >= 283
-        btScaledBvhTriangleMeshShape* newShape = new btScaledBvhTriangleMeshShape(trishape, btVector3(1.f, 1.f, 1.f));
+        btScaledBvhTriangleMeshShape* newShape = new btScaledBvhTriangleMeshShape(const_cast<btBvhTriangleMeshShape*>(trishape), btVector3(1.f, 1.f, 1.f));
 #else
         // work around btScaledBvhTriangleMeshShape bug ( https://code.google.com/p/bullet/issues/detail?id=371 ) in older bullet versions
-        btTriangleMesh* oldMesh = static_cast<btTriangleMesh*>(trishape->getMeshInterface());
+        const btTriangleMesh* oldMesh = static_cast<const btTriangleMesh*>(trishape->getMeshInterface());
         btTriangleMesh* newMesh = new btTriangleMesh(*oldMesh);
 
         // Do not build a new bvh (not needed, since it's the same as the original shape's bvh)
-        bool buildBvh = true;
-        if (trishape->getOptimizedBvh())
-            buildBvh = false;
-        TriangleMeshShape* newShape = new TriangleMeshShape(newMesh, true, buildBvh);
+        btOptimizedBvh* bvh = const_cast<btBvhTriangleMeshShape*>(trishape)->getOptimizedBvh();
+        TriangleMeshShape* newShape = new TriangleMeshShape(newMesh, true, bvh == NULL);
         // Set original shape's bvh via pointer
         // The pointer is safe because the BulletShapeInstance keeps a ref_ptr to the original BulletShape
-        if (!buildBvh)
-            newShape->setOptimizedBvh(trishape->getOptimizedBvh());
+        if (bvh)
+            newShape->setOptimizedBvh(bvh);
 #endif
         return newShape;
     }
 
-    if (btBoxShape* boxshape = dynamic_cast<btBoxShape*>(shape))
+    if (const btBoxShape* boxshape = dynamic_cast<const btBoxShape*>(shape))
     {
         return new btBoxShape(*boxshape);
     }
@@ -98,13 +96,13 @@ btCollisionShape *BulletShape::getCollisionShape()
     return mCollisionShape;
 }
 
-osg::ref_ptr<BulletShapeInstance> BulletShape::makeInstance()
+osg::ref_ptr<BulletShapeInstance> BulletShape::makeInstance() const
 {
     osg::ref_ptr<BulletShapeInstance> instance (new BulletShapeInstance(this));
     return instance;
 }
 
-BulletShapeInstance::BulletShapeInstance(osg::ref_ptr<BulletShape> source)
+BulletShapeInstance::BulletShapeInstance(osg::ref_ptr<const BulletShape> source)
     : BulletShape()
     , mSource(source)
 {

components/resource/bulletshape.hpp

@@ -38,9 +38,9 @@ namespace Resource
         // we store the node's record index mapped to the child index of the shape in the btCompoundShape.
         std::map<int, int> mAnimatedShapes;
 
-        osg::ref_ptr<BulletShapeInstance> makeInstance();
+        osg::ref_ptr<BulletShapeInstance> makeInstance() const;
 
-        btCollisionShape* duplicateCollisionShape(btCollisionShape* shape) const;
+        btCollisionShape* duplicateCollisionShape(const btCollisionShape* shape) const;
 
         btCollisionShape* getCollisionShape();
 
@@ -55,10 +55,10 @@ namespace Resource
     class BulletShapeInstance : public BulletShape
     {
     public:
-        BulletShapeInstance(osg::ref_ptr<BulletShape> source);
+        BulletShapeInstance(osg::ref_ptr<const BulletShape> source);
 
     private:
-        osg::ref_ptr<BulletShape> mSource;
+        osg::ref_ptr<const BulletShape> mSource;
     };
 
     // Subclass btBhvTriangleMeshShape to auto-delete the meshInterface

components/resource/bulletshapemanager.cpp

@@ -109,7 +109,7 @@ BulletShapeManager::~BulletShapeManager()
 
 }
 
-osg::ref_ptr<BulletShapeInstance> BulletShapeManager::createInstance(const std::string &name)
+osg::ref_ptr<const BulletShape> BulletShapeManager::getShape(const std::string &name)
 {
     std::string normalized = name;
     mVFS->normalizeFilename(normalized);
@@ -142,13 +142,18 @@ osg::ref_ptr<BulletShapeInstance> BulletShapeManager::createInstance(const std::
             if (!shape)
             {
                 mCache->addEntryToObjectCache(normalized, NULL);
-                return osg::ref_ptr<BulletShapeInstance>();
+                return osg::ref_ptr<BulletShape>();
             }
         }
 
         mCache->addEntryToObjectCache(normalized, shape);
     }
+    return shape;
+}
 
+osg::ref_ptr<BulletShapeInstance> BulletShapeManager::createInstance(const std::string &name)
+{
+    osg::ref_ptr<const BulletShape> shape = getShape(name);
     if (shape)
         return shape->makeInstance();
     else

components/resource/bulletshapemanager.hpp

@@ -26,6 +26,9 @@ namespace Resource
         BulletShapeManager(const VFS::Manager* vfs, SceneManager* sceneMgr, NifFileManager* nifFileManager);
         ~BulletShapeManager();
 
+        osg::ref_ptr<const BulletShape> getShape(const std::string& name);
+
+        /// Shorthand for getShape(name)->makeInstance();
         osg::ref_ptr<BulletShapeInstance> createInstance(const std::string& name);
 
     private: