make llGetGeometricCenter() work as in current SL. Now this is not real geom center but a average of positions relative to root prim ignoring prims details, so no need to use physics engine.

OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs

@@ -3956,6 +3956,34 @@ namespace OpenSim.Region.Framework.Scenes
             }
         }
 
+        public Vector3 GetGeometricCenter()
+        {
+            // this is not real geometric center but a average of positions relative to root prim acording to
+            // http://wiki.secondlife.com/wiki/llGetGeometricCenter
+            // ignoring tortured prims details since sl also seems to ignore
+            // so no real use in doing it on physics
+            
+            Vector3 gc = Vector3.Zero;
+
+            int nparts = m_parts.Count;
+            if (nparts <= 1)
+                return gc;
+
+            SceneObjectPart[] parts = m_parts.GetArray();
+            nparts = parts.Length; // just in case it changed
+            if (nparts <= 1)
+                return gc;
+
+            // average all parts positions
+            for (int i = 0; i < nparts; i++)
+                gc += parts[i].GetWorldPosition();
+            gc /= nparts;
+
+            // relative to root:
+            gc -= AbsolutePosition;
+            return gc;
+        }
+
         public float GetMass()
         {
             float retmass = 0f;

OpenSim/Region/Framework/Scenes/SceneObjectPart.cs

@@ -2260,18 +2260,29 @@ namespace OpenSim.Region.Framework.Scenes
 
         public Vector3 GetGeometricCenter()
         {
-            PhysicsActor pa = PhysActor;
+            // this is not real geometric center but a average of positions relative to root prim acording to
-
+            // http://wiki.secondlife.com/wiki/llGetGeometricCenter
-            if (pa != null)
+            // ignoring tortured prims details since sl also seems to ignore
-            {
+            // so no real use in doing it on physics
-                Vector3 vtmp = pa.CenterOfMass;
+            if (ParentGroup.IsDeleted)
-                return vtmp;
-            }
-            else
                 return new Vector3(0, 0, 0);
+
+            return ParentGroup.GetGeometricCenter();
+
+            /*
+                        PhysicsActor pa = PhysActor;
+
+                        if (pa != null)
+                        {
+                            Vector3 vtmp = pa.CenterOfMass;
+                            return vtmp;
+                        }
+                        else
+                            return new Vector3(0, 0, 0);
+             */
         }
 
-        public float GetMass()
+         public float GetMass()
         {
             PhysicsActor pa = PhysActor;