From c8654724e2aa2fd2f7c224b1c1274a18d1c17a52 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Loriot?= <sebastien.loriot@cgal.org>
Date: Mon, 13 Jun 2022 12:41:57 +0200
Subject: [PATCH] update test to check we can prevent collapses and flips

---
 .../test_remove_caps_needles.cpp              | 47 +++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/Polygon_mesh_processing/test/Polygon_mesh_processing/test_remove_caps_needles.cpp b/Polygon_mesh_processing/test/Polygon_mesh_processing/test_remove_caps_needles.cpp
index ed99bc0b0b7..b57a3dc8e8d 100644
--- a/Polygon_mesh_processing/test/Polygon_mesh_processing/test_remove_caps_needles.cpp
+++ b/Polygon_mesh_processing/test/Polygon_mesh_processing/test_remove_caps_needles.cpp
@@ -5,6 +5,7 @@
 #include <fstream>
 #include <CGAL/Polygon_mesh_processing/repair_degeneracies.h>
 #include <CGAL/Polyhedral_envelope.h>
+#include <CGAL/Polygon_mesh_processing/measure.h>
 
 #include <iostream>
 #include <vector>
@@ -116,7 +117,49 @@ void test_with_envelope(std::string filename, double eps)
     std::cout << "  Output mesh has self-intersections\n";
 }
 
+bool same_meshes(const Mesh& m1, const Mesh& m2)
+{
+  std::size_t c=0, m1_only=0, m2_only=0;
+  PMP::match_faces(m1, m2, CGAL::Counting_output_iterator(&c)
+                         , CGAL::Counting_output_iterator(&m1_only)
+                         , CGAL::Counting_output_iterator(&m2_only));
+  return m1_only==0 && m2_only==0;
+}
+void test_parameters_on_pig(std::string filename)
+{
+  std::ifstream input(filename);
 
+  Mesh mesh, bk;
+  if (!input || !(input >> mesh) || !CGAL::is_triangle_mesh(mesh)) {
+    std::cerr << "Not a valid input file." << std::endl;
+    exit(EXIT_FAILURE);
+  }
+
+  bk=mesh;
+
+  PMP::experimental::remove_almost_degenerate_faces(mesh,
+                                                    std::cos(160. / 180 * CGAL_PI),
+                                                    4,
+                                                    9999 /*no_constraints*/);
+  assert(vertices(mesh).size()!=vertices(bk).size());
+
+  mesh=bk;
+  PMP::experimental::remove_almost_degenerate_faces(mesh,
+                                                    std::cos(160. / 180 * CGAL_PI),
+                                                    4,
+                                                    0.000000000000001); // no-collapse but flips
+  assert(vertices(mesh).size()==vertices(bk).size());
+  assert(!same_meshes(mesh,bk));
+
+  mesh=bk;
+  PMP::experimental::remove_almost_degenerate_faces(mesh,
+                                                    std::cos(160. / 180 * CGAL_PI),
+                                                    4,
+                                                    0.000000000000001,
+                                                    CGAL::parameters::flip_triangle_height_threshold(0.000000000000001)); // no-collapse and no flip
+  assert(vertices(mesh).size()==vertices(bk).size());
+  assert(same_meshes(mesh,bk));
+}
 
 int main(int argc, char** argv)
 {
@@ -129,5 +172,9 @@ int main(int argc, char** argv)
     if (argc==3)
       test_with_envelope(filename, atof(argv[2]));
 
+  // only run that test with pig.off
+  if (argc==1)
+    test_parameters_on_pig(filename);
+
   return 0;
 }