Refactor resolve_duplicated_faces() into its own file.

Former-commit-id: 2908614bb4c7e46ed7efc994f1ae036412ae56b6

include/igl/resolve_duplicated_faces.cpp

@@ -0,0 +1,89 @@
+// This file is part of libigl, a simple c++ geometry processing library.
+// 
+// Copyright (C) 2015 Qingnan Zhou <qnzhou@gmail.com>
+// 
+// This Source Code Form is subject to the terms of the Mozilla Public License 
+// v. 2.0. If a copy of the MPL was not distributed with this file, You can 
+// obtain one at http://mozilla.org/MPL/2.0/.
+//
+
+#include "resolve_duplicated_faces.h"
+
+#include "slice.h"
+#include "unique_simplices.h"
+
+template<
+  typename DerivedF1,
+  typename DerivedF2,
+  typename DerivedJ >
+IGL_INLINE void igl::resolve_duplicated_faces(
+    const Eigen::PlainObjectBase<DerivedF1>& F1,
+    Eigen::PlainObjectBase<DerivedF2>& F2,
+    Eigen::PlainObjectBase<DerivedJ>& J) {
+
+  typedef typename DerivedF1::Scalar Index;
+  Eigen::VectorXi IA,IC;
+  DerivedF1 uF;
+  igl::unique_simplices(F1,uF,IA,IC);
+
+  const size_t num_faces = F1.rows();
+  const size_t num_unique_faces = uF.rows();
+  assert(IA.rows() == num_unique_faces);
+  // faces on top of each unique face
+  std::vector<std::vector<int> > uF2F(num_unique_faces);
+  // signed counts
+  Eigen::VectorXi counts = Eigen::VectorXi::Zero(num_unique_faces);
+  Eigen::VectorXi ucounts = Eigen::VectorXi::Zero(num_unique_faces);
+  // loop over all faces
+  for (size_t i=0; i<num_faces; i++) {
+    const size_t ui = IC(i);
+    const bool consistent = 
+      (F1(i,0) == uF(ui, 0) && F1(i,1) == uF(ui, 1) && F1(i,2) == uF(ui, 2)) ||
+      (F1(i,0) == uF(ui, 1) && F1(i,1) == uF(ui, 2) && F1(i,2) == uF(ui, 0)) ||
+      (F1(i,0) == uF(ui, 2) && F1(i,1) == uF(ui, 0) && F1(i,2) == uF(ui, 1));
+    uF2F[ui].push_back(int(i+1) * (consistent?1:-1));
+    counts(ui) += consistent ? 1:-1;
+    ucounts(ui)++;
+  }
+
+  std::vector<size_t> kept_faces;
+  for (size_t i=0; i<num_unique_faces; i++) {
+    if (ucounts[i] == 1) {
+      kept_faces.push_back(abs(uF2F[i][0])-1);
+      continue;
+    }
+    if (counts[i] == 1) {
+      bool found = false;
+      for (auto fid : uF2F[i]) {
+        if (fid > 0) {
+          kept_faces.push_back(abs(fid)-1);
+          found = true;
+          break;
+        }
+      }
+      assert(found);
+    } else if (counts[i] == -1) {
+      bool found = false;
+      for (auto fid : uF2F[i]) {
+        if (fid < 0) {
+          kept_faces.push_back(abs(fid)-1);
+          found = true;
+          break;
+        }
+      }
+      assert(found);
+    } else {
+      assert(counts[i] == 0);
+    }
+  }
+
+  const size_t num_kept = kept_faces.size();
+  J.resize(num_kept, 1);
+  std::copy(kept_faces.begin(), kept_faces.end(), J.data());
+  igl::slice(F1, J, 1, F2);
+}
+
+#ifdef IGL_STATIC_LIBRARY
+template void igl::resolve_duplicated_faces<Eigen::Matrix<int, -1, -1, 0, -1, -1>, Eigen::Matrix<int, -1, -1, 0, -1, -1>, Eigen::Matrix<int, -1, 1, 0, -1, 1> >(Eigen::PlainObjectBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&, Eigen::PlainObjectBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> >&, Eigen::PlainObjectBase<Eigen::Matrix<int, -1, 1, 0, -1, 1> >&);
+template void igl::resolve_duplicated_faces<Eigen::Matrix<int, -1, -1, 0, -1, -1>, Eigen::Matrix<int, -1, -1, 0, -1, -1>, Eigen::Matrix<long, -1, 1, 0, -1, 1> >(Eigen::PlainObjectBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&, Eigen::PlainObjectBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> >&, Eigen::PlainObjectBase<Eigen::Matrix<long, -1, 1, 0, -1, 1> >&);
+#endif

include/igl/resolve_duplicated_faces.h

@@ -0,0 +1,52 @@
+// This file is part of libigl, a simple c++ geometry processing library.
+// 
+// Copyright (C) 2015 Qingnan Zhou <qnzhou@gmail.com>
+// 
+// This Source Code Form is subject to the terms of the Mozilla Public License 
+// v. 2.0. If a copy of the MPL was not distributed with this file, You can 
+// obtain one at http://mozilla.org/MPL/2.0/.
+//
+#ifndef IGL_COPYLEFT_RESOLVE_DUPLICATED_FACES
+#define IGL_COPYLEFT_RESOLVE_DUPLICATED_FACES
+
+#include "igl_inline.h"
+#include <Eigen/Core>
+
+namespace igl {
+
+  // Resolve duplicated faces according to the following rules per unique face:
+  //
+  // 1. If the number of positively oriented faces equals the number of
+  //    negatively oriented faces, remove all duplicated faces at this triangle.
+  // 2. If the number of positively oriented faces equals the number of
+  //    negatively oriented faces plus 1, keeps one of the positively oriented
+  //    face.
+  // 3. If the number of positively oriented faces equals the number of
+  //    negatively oriented faces minus 1, keeps one of the negatively oriented
+  //    face.
+  // 4. If the number of postively oriented faces differ with the number of
+  //    negativley oriented faces by more than 1, the mesh is not orientable.
+  //    An exception will be thrown.
+  //
+  // Inputs:
+  //   F1  #F1 by 3 array of input faces.
+  //
+  // Outputs:
+  //   F2  #F2 by 3 array of output faces without duplicated faces.
+  //   J   #F2 list of indices into F1.
+  template<
+    typename DerivedF1,
+    typename DerivedF2,
+    typename DerivedJ >
+  IGL_INLINE void resolve_duplicated_faces(
+      const Eigen::PlainObjectBase<DerivedF1>& F1,
+      Eigen::PlainObjectBase<DerivedF2>& F2,
+      Eigen::PlainObjectBase<DerivedJ>& J);
+
+}
+
+#ifndef IGL_STATIC_LIBRARY
+#  include "resolve_duplicated_faces.cpp"
+#endif
+
+#endif