change namespace and add doc

Polygon_mesh_processing/examples/Polygon_mesh_processing/polyhedral_envelope.cpp

@@ -0,0 +1,38 @@
+
+#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
+#include <CGAL/Envelope.h>
+#include <CGAL/Surface_mesh.h>
+
+#include <fstream>
+
+int main(int argc, char* argv[])
+{
+  typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
+  typedef Kernel::Point_3 Point_3;
+  typedef CGAL::Surface_mesh<Point_3> Surface_mesh;
+  typedef boost::graph_traits<Surface_mesh>::vertex_descriptor vertex_descriptor;
+
+  typedef CGAL::Envelope<Kernel> Envelope;
+
+  std::ifstream in((argc>1) ? argv[1] : "data/unitsphere.off");
+  Surface_mesh tmesh;
+
+  in >> tmesh;
+
+  double eps = (argc>2) ? std::stod(std::string(argv[2])) : 0.2;
+
+  Envelope envelope(tmesh, eps);
+
+  int i = (argc>3) ? std::stoi(std::string(argv[3])) : 0;
+  int j = (argc>4) ? std::stoi(std::string(argv[4])) : 100;
+  int k = (argc>5) ? std::stoi(std::string(argv[5])) : 200;
+
+  if(envelope(tmesh.point(vertex_descriptor(i)),
+              tmesh.point(vertex_descriptor(j)),
+              tmesh.point(vertex_descriptor(k)))){
+
+    std::cout << "inside polyhedral envelope" << std::endl;
+  }
+
+  return 0;
+}