From c523c0d61f55faa8c3e71be29c51da884846a4f6 Mon Sep 17 00:00:00 2001
From: Mike Kremer <mkremer@cs.rwth-aachen.de>
Date: Wed, 7 Nov 2012 12:17:19 +0000
Subject: [PATCH] Added function to get the genus of a mesh.

git-svn-id: http://www.openvolumemesh.org/svnrepo/OpenVolumeMesh/trunk@231 66977474-1d4b-4f09-8fe9-267525286df2
---
 src/OpenVolumeMesh/Core/TopologyKernel.hh | 7 +++++++
 src/Unittests/unittests_basics.hh         | 7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/src/OpenVolumeMesh/Core/TopologyKernel.hh b/src/OpenVolumeMesh/Core/TopologyKernel.hh
index 7b6f049..d23cb60 100644
--- a/src/OpenVolumeMesh/Core/TopologyKernel.hh
+++ b/src/OpenVolumeMesh/Core/TopologyKernel.hh
@@ -226,6 +226,13 @@ public:
     /// Get number of cells in mesh
     virtual unsigned int n_cells()      const { return cells_.size(); }
 
+    unsigned int genus() const {
+        return  (1 - (n_vertices() -
+                      n_edges() +
+                      n_faces() -
+                      n_cells())/2.0);
+    }
+
 private:
 
     // Cache total vertex number
diff --git a/src/Unittests/unittests_basics.hh b/src/Unittests/unittests_basics.hh
index 91f3d47..e8297ce 100644
--- a/src/Unittests/unittests_basics.hh
+++ b/src/Unittests/unittests_basics.hh
@@ -482,6 +482,13 @@ TEST_F(HexahedralMeshBase, TopologyCheckFail) {
     EXPECT_EQ(HexahedralMesh::InvalidCellHandle, mesh_.add_cell(chfaces, true));
 }
 
+TEST_F(PolyhedralMeshBase, VolumeMeshGenus) {
+
+    generatePolyhedralMesh(mesh_);
+
+    EXPECT_EQ(0, mesh_.genus());
+}
+
 TEST_F(PolyhedralMeshBase, VolumeMeshConnectivity) {
 
     generatePolyhedralMesh(mesh_);
-- 
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