Added a method to clear collision data. This is often

necessary when modifying the mesh in some way.  Previously,
the only other option was to force creation of the collision
data for every change but this is wasteful since the collision
data does not need to be regenerated until collideWith() is
called.


git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@10951 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/core/com/jme3/scene/Mesh.java

@@ -887,6 +887,15 @@ public class Mesh implements Savable, Cloneable {
         collisionTree = tree;
     }
 
+    /**
+     * Clears any previously generated collision data.  Use this if
+     * the mesh has changed in some way that invalidates any previously
+     * generated BIHTree.
+     */
+    public void clearCollisionData() {
+        collisionTree = null;
+    }
+
     /**
      * Handles collision detection, internal use only.
      * User code should only use collideWith() on scene