free function API init with explicit method

Surface_mesh_approximation/examples/Surface_mesh_approximation/vsa_example.cpp

@@ -25,10 +25,10 @@ int main()
   std::vector<std::size_t> triangles;
   std::vector<Kernel::Point_3> anchors;
 
-  // free function interface with named parameters, seperated with dots
+  // free function interface with named parameters, separated with dots
   CGAL::vsa_mesh_approximation(input, output,
     CGAL::VSA::parameters::init_by_number(200). // seeding by target number of proxies
-      init_method(1). // hierarchical init
+      init_method(CGAL::Method::Hierarchical). // hierarchical init
       iterations(30). // number of relaxation iterations after seeding
       anchor_point(std::back_inserter(anchors)). // get anchor points
       indexed_triangles(std::back_inserter(triangles))); // get indexed triangles

Surface_mesh_approximation/include/CGAL/VSA_approximation.h

@@ -32,6 +32,16 @@
 
 namespace CGAL
 {
+  /// Seeding method enumeration
+  enum Method {
+    /// Random seeding
+    Random,
+    /// Incremental seeding
+    Incremental,
+    /// Hierarchical seeding
+    Hierarchical
+  };
+
 /*!
  * \ingroup PkgTSMA
  * @brief Main class for Variational Shape Approximation algorithm.

Surface_mesh_approximation/include/CGAL/vsa_mesh_approximation.h

@@ -93,7 +93,7 @@ bool vsa_mesh_approximation(const TriangleMesh &tm_in,
   vsa_l21.set_metric(l21_metric, l21_fitting);
 
   // default random initialization
-  int init = choose_param(get_param(np, internal_np::init_method), 0);
+  CGAL::Method init = choose_param(get_param(np, internal_np::init_method), CGAL::Method::Random);
   std::size_t num_proxies = choose_param(get_param(np, internal_np::init_by_number), 0);
   std::size_t inner_iterations = choose_param(get_param(np, internal_np::inner_iterations), 10);
   if (num_proxies == 0 || num_proxies > num_faces(tm_in)) {