From 00315138355543dea8d7788f51ac64e261bfa4eb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20M=C3=B6bius?= <moebius@cs.rwth-aachen.de>
Date: Tue, 16 Feb 2021 13:13:15 +0100
Subject: [PATCH] Fixed a crash in the modified butterfly subdivider with
 vertices with valance larger than 30.

---
 .../Subdivider/Uniform/ModifiedButterFlyT.hh  |  11 +++++++++
 src/Unittests/TestFiles/cylinder.om           | Bin 0 -> 1198 bytes
 src/Unittests/unittests_subdivider_uniform.cc |  22 ++++++++++++++++++
 3 files changed, 33 insertions(+)
 create mode 100644 src/Unittests/TestFiles/cylinder.om

diff --git a/src/OpenMesh/Tools/Subdivider/Uniform/ModifiedButterFlyT.hh b/src/OpenMesh/Tools/Subdivider/Uniform/ModifiedButterFlyT.hh
index 78b8f806..f476ad1f 100644
--- a/src/OpenMesh/Tools/Subdivider/Uniform/ModifiedButterFlyT.hh
+++ b/src/OpenMesh/Tools/Subdivider/Uniform/ModifiedButterFlyT.hh
@@ -179,6 +179,17 @@ protected:
 
     ///TODO:Implement fixed positions
 
+    // Compute the maximal vertex valence in the mesh
+    unsigned int maxValence = 0;
+    for ( auto vertex : _m.vertices() ) {
+        maxValence = std::max(maxValence,_m.valence(vertex));
+    }
+
+    // We pre initialized with 30. If it's larger, we update the weights
+    if (maxValence >= 30) {
+        init_weights( maxValence + 1 );
+    }
+
     // Do _n subdivisions
     for (size_t i=0; i < _n; ++i)
     {
diff --git a/src/Unittests/TestFiles/cylinder.om b/src/Unittests/TestFiles/cylinder.om
new file mode 100644
index 0000000000000000000000000000000000000000..7036e0a3ae74fe35c8c93bf22cdbbaddf518e1a0
GIT binary patch
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literal 0
HcmV?d00001

diff --git a/src/Unittests/unittests_subdivider_uniform.cc b/src/Unittests/unittests_subdivider_uniform.cc
index 835c89cf..53900233 100644
--- a/src/Unittests/unittests_subdivider_uniform.cc
+++ b/src/Unittests/unittests_subdivider_uniform.cc
@@ -1027,6 +1027,28 @@ TEST_F(OpenMeshSubdividerUniform_Triangle, Modified_Butterfly) {
 
 
 
+TEST_F(OpenMeshSubdividerUniform_Triangle, Modified_Butterfly_cylinder) {
+    mesh_.clear();
+
+    OpenMesh::IO::read_mesh(mesh_, "cylinder.om");
+
+    // Initialize subdivider
+    OpenMesh::Subdivider::Uniform::ModifiedButterflyT<Mesh> butter;
+
+    // Check setup
+    EXPECT_EQ(66u, mesh_.n_vertices() ) << "Wrong number of vertices";
+    EXPECT_EQ(128u, mesh_.n_faces() )    << "Wrong number of faces";
+
+    // Execute 3 subdivision steps
+    butter( mesh_,3,true );
+
+    // Check setup
+    EXPECT_EQ(4098u, mesh_.n_vertices() ) << "Wrong number of vertices after subdivision with loop";
+    EXPECT_EQ(8192u, mesh_.n_faces() )    << "Wrong number of faces after subdivision with loop";
+}
+
+
+
 TEST_F(OpenMeshSubdividerUniform_Triangle, Modified_Butterfly_delete_vertex) {
 
   for (bool collect_garbage : { false, true })