private String multiPrimitiveCoordToString(MultiPrimitive mp) {
Iterator<Primitive> primitives = (Iterator<Primitive>) mp.getElements().iterator();
String rString = "";
while (primitives.hasNext()) {
Primitive p = primitives.next();
if (p instanceof Point)
rString += "\n\t" + pointToString((Point) p);
else if (p instanceof Curve)
rString += "\n\t" + curveToString((Curve) p);
else if (p instanceof Surface)