public Vec2 toPoint(Point2D p){
  return new Vec2(toMeters(p.getX()),toMeters(appHeight - p.getY()));
}

public Vec2 toPoint ( Point2D p ) { return new Vec2 ( toMeters ( p . getX ( ) ) , toMeters ( appHeight - p . getY ( ) ) ) ; }
converts a point in pixel space to a point in physics space .
