Use ImplicitSurface.center in marching cubes

Implicit.hpp

@@ -6,7 +6,7 @@ class ImplicitSurface {
     public:
         virtual double operator() (double x, double y, double z) const = 0;
         double operator()(const Point& pt) const;
-        Point getCenter() { return center;}
+        Point getCenter() const { return center;}
     protected:
         Point center;
         ImplicitSurface(Point _center) : center(_center) {}

MarchingCubes.cpp

@@ -19,6 +19,7 @@ Mesh MarchingCubes::operator()() {
     Mesh output;
 
     without_hints(output);
+    output.translate(surface.getCenter());
 
     return output;
 }