From faadf52a540c51ef0c893c31997826e9c8a0a46f Mon Sep 17 00:00:00 2001
From: Jane Tournois <jane.tournois@geometryfactory.com>
Date: Fri, 9 Jun 2017 12:08:04 +0200
Subject: [PATCH] make the random generator seeding integer a named parameter

---
 .../internal/parameters_interface.h           |  2 ++
 .../random_perturbation.h                     | 20 ++++++++++---------
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/parameters_interface.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/parameters_interface.h
index 8feab1527d8..c9c5c27313c 100644
--- a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/parameters_interface.h
+++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/parameters_interface.h
@@ -44,8 +44,10 @@ CGAL_add_named_parameter(number_of_points_per_edge_t, number_of_points_per_edge,
 CGAL_add_named_parameter(number_of_points_on_edges_t, number_of_points_on_edges, number_of_points_on_edges)
 CGAL_add_named_parameter(nb_points_per_area_unit_t, nb_points_per_area_unit, number_of_points_per_area_unit)
 CGAL_add_named_parameter(nb_points_per_distance_unit_t, nb_points_per_distance_unit, number_of_points_per_distance_unit)
+
 //to be documented
 CGAL_add_named_parameter(face_normal_t, face_normal, face_normal_map)
+CGAL_add_named_parameter(random_seed_t, random_seed, random_seed)
 
 //internal
 CGAL_add_named_parameter(weight_calculator_t, weight_calculator, weight_calculator)
diff --git a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/random_perturbation.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/random_perturbation.h
index 79724b84d94..ecd0efb7553 100644
--- a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/random_perturbation.h
+++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/random_perturbation.h
@@ -46,12 +46,12 @@ namespace Polygon_mesh_processing {
 
 namespace internal {
 
-  template<typename GT, typename PM, typename VCMap, typename VPMap>
+  template<typename GT, typename PM, typename VCMap, typename VPMap, typename RNG>
   void random_perturbation_impl(PM& tmesh,
                                 const double& max_size,
                                 VCMap vcmap,
                                 VPMap vpmap,
-                                const int seed,
+                                RNG& rng,
                                 const GT& gt)
   {
     typedef typename boost::graph_traits<PM>::vertex_descriptor vertex_descriptor;
@@ -65,8 +65,6 @@ namespace internal {
     Tree tree(faces(tmesh).first, faces(tmesh).second, tmesh);
     tree.accelerate_distance_queries();
 
-    CGAL::Random rng(seed);
-
     typename GT::Construct_translated_point_3 translate
       = gt.construct_translated_point_3_object();
     typename GT::Construct_vector_3 vec
@@ -112,6 +110,8 @@ namespace internal {
 *    constrained-or-not status of each vertex of `tmesh`. A constrained vertex
 *    cannot be modified at all during remeshing
 *  \cgalParamEnd
+*  \cgalParambegin{random_seed} an non-negative integer value to seed the random
+      number generator, and make the perturbation deterministic
 * \cgalNamedParamsEnd
 *
 */
@@ -149,12 +149,14 @@ void random_perturbation(TriangleMesh& tmesh
   VCMap vcmap = choose_param(get_param(np, internal_np::vertex_is_constrained),
                              internal::No_constraint_pmap<vertex_descriptor>());
 
+  unsigned int seed = choose_param(get_param(np, internal_np::random_seed), -1);
+
   internal::random_perturbation_impl(tmesh,
-                                         perturbation_max_size,
-                                         vcmap,
-                                         vpmap,
-                                         0/*seed*/,
-                                         gt);
+          perturbation_max_size,
+          vcmap,
+          vpmap,
+          ((seed == -1) ? CGAL::Random() : CGAL::Random(seed)),
+          gt);
 
 #ifdef CGAL_PMP_RANDOM_PERTURBATION_VERBOSE
   t.stop();