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diff --git a/intern/opensubdiv/internal/opensubdiv_converter_orient_impl.h b/intern/opensubdiv/internal/opensubdiv_converter_orient_impl.h
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+++ b/intern/opensubdiv/internal/opensubdiv_converter_orient_impl.h
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+// Copyright 2018 Blender Foundation. All rights reserved.
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software Foundation,
+// Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+//
+// Author: Sergey Sharybin
+
+#ifndef OPENSUBDIV_CONVERTER_ORIENT_IMPL_H_
+#define OPENSUBDIV_CONVERTER_ORIENT_IMPL_H_
+
+#include "internal/opensubdiv_converter_orient.h"
+
+#include <algorithm>
+#include <cmath>
+#include <utility>
+
+namespace opensubdiv_capi {
+
+inline void reverseFaceVertices(int* face_vertices, const int num_vertices) {
+  int last_vert = face_vertices[num_vertices - 1];
+  for (int i = num_vertices - 1; i > 0; --i) {
+    face_vertices[i] = face_vertices[i - 1];
+  }
+  face_vertices[0] = last_vert;
+}
+
+inline int getLoopWinding(int vert0_of_face, int vert1_of_face) {
+  int delta_face = vert1_of_face - vert0_of_face;
+  if (abs(delta_face) != 1) {
+    if (delta_face > 0) {
+      delta_face = -1;
+    } else {
+      delta_face = 1;
+    }
+  }
+  return delta_face;
+}
+
+inline void reverseFaceLoops(
+    OpenSubdiv::Far::IndexArray* face_vertices,
+    OpenSubdiv::Far::IndexArray* face_edges) {
+  const int num_face_vertices = face_vertices->size();
+  for (int i = 0; i < num_face_vertices / 2; ++i) {
+    const int j = num_face_vertices - i - 1;
+    if (i != j) {
+      std::swap((*face_vertices)[i], (*face_vertices)[j]);
+      std::swap((*face_edges)[i], (*face_edges)[j]);
+    }
+  }
+  reverseFaceVertices(&(*face_vertices)[0], num_face_vertices);
+}
+
+}  // namespace opensubdiv_capi
+
+#endif  // OPENSUBDIV_CONVERTER_ORIENT_IMPL_H_