         case .RotationX, .RotationY, .RotationZ:
             let angle = frame.values.first! / 180.0 * M_PI
             return angle
+        case .Scale:
+            fatalError("please extract to .ScaleX, .ScaleY, .ScaleZ first.")
         }
     }
 }
    case RotationX
    case RotationY
    case RotationZ
}

struct CurveData {
    let frames : [FrameData]

        return FrameData(time: time, values: values)
    }
    
    public func animation(name:String, ofProperty prop:Property) -> CAAnimation? {
        return animation(name, ofProperty: prop, center: CGPointZero)
    }
