Implemented but untested

vtkm/exec/cellmetrics/CellSkewMertic.h

+//============================================================================
+//  Copyright (c) Kitware, Inc.
+//  All rights reserved.
+//  See LICENSE.txt for details.
+//  This software is distributed WITHOUT ANY WARRANTY; without even
+//  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+//  PURPOSE.  See the above copyright notice for more information.
+//
+//  Copyright 2014 National Technology & Engineering Solutions of Sandia, LLC (NTESS).
+//  Copyright 2014 UT-Battelle, LLC.
+//  Copyright 2014 Los Alamos National Security.
+//
+//  Under the terms of Contract DE-NA0003525 with NTESS,
+//  the U.S. Government retains certain rights in this software.
+//
+//  Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
+//  Laboratory (LANL), the U.S. Government retains certain rights in
+//  this software.
+//============================================================================
+#ifndef vtk_m_exec_CellSkewMetric_h
+#define vtk_m_exec_CellSkewMetric_h
+/*
+ */
+
+#include "vtkm/CellShape.h"
+#include "vtkm/CellTraits.h"
+#include "vtkm/VecTraits.h"
+#include "vtkm/VectorAnalysis.h"
+#include "vtkm/exec/FunctorBase.h"
+#include "vtkm/exec/cellmetrics/CellConditionMetric.h"
+
+namespace vtkm
+{
+namespace exec
+{
+static constexpr FloatType FLOAT_MAX = vtkm::Infinity<FloatType>();
+static constexpr FloatType FLOAT_MIN = vtkm::NegativeInfinity<FloatType>();
+
+template <typename OutType, typename PointCoordVecType, typename CellShapeType>
+VTKM_EXEC OutType CellStretchMetric(const vtkm::IdComponent& numPts,
+                                    const PointCoordVecType& pts,
+                                    CellShapeType shape,
+                                    const vtkm::exec::FunctorBase& worklet)
+{
+    worklet.RaiseError("Shape type template must be specified to compute skew")
+    return OutType(-1.0);
+}
+
+template <typename OutType, typename PointCoordVecType>
+VTKM_EXEC OutType CellSkewMetric(const vtkm::IdComponents &numPts,
+                                  const PointCoordVecType& pts,
+                                  vtkm::CellShapeHex,
+                                  const vtkm::exec::FunctorBase& worklet)
+{
+    FloatType X1 = (pts[1] - pts[0]) + (pts[2] - pts[3]) + (pts[5] - pts[4]) + (pts[6] - pts[7]);
+    FloatType X1_mag = vtkm::Magnitude(X1);
+    if (X1_mag < FLOAT_MIN)
+        return FLOAT_MAX;
+    FloatType x1 = X1/X1_mag;
+    FloatType X2 = (pts[3] - pts[0]) + (pts[2] - pts[1]) + (pts[7] - pts[4]) + (pts[6] - pts[5]);
+    FloatType X2_mag = vtkm::Magnitude(X2);
+    if (X2_mag < FLOAT_MIN)
+        return FLOAT_MAX;
+    FloatType x2 = X2/X2_mag;
+    FloatType X3 = (pts[4] - pts[0]) + (pts[5] - pts[1]) + (pts[6] - pts[2]) + (pts[7] - pts[3]);
+    FloatType X3_mag = vtkm::Magnitude(X3);
+    if (X3_mag < FLOAT_MIN)
+        return FLOAT_MAX;
+    FloatType x3 = X3/X3_mag;
+    return vtkm::Max(vtkm::Dot(x1,x2),vtkm::Max(vtkm::Dot(x1,x3),vtkm::Dot(x2,x3)));
+}
+
+template <typename OutType, typename PointCoordVecType>
+VTKM_EXEC OutType CellSkewMetric(const vtkm::IdComponents &numPts,
+                                  const PointCoordVecType& pts,
+                                  vtkm::CellShapeQuad,
+                                  const vtkm::exec::FunctorBase& worklet)
+{
+    FloatType X1 = (pts[1] - pts[0]) + (pts[2] - pts[3]);
+    FloatType X1_mag = vtkm::Magnitude(X1);
+    if (X1_mag < FLOAT_MIN)
+        return 0;
+    FloatType x1 = X1/X1_mag;
+    FloatType X2 = (pts[2] - pts[1]) + (pts[3] - pts[0]);
+    FloatType X2_mag = vtkm::Magnitude(X2);
+    if (X2_mag < FLOAT_MIN)
+        return 0;
+    FloatType x2 = X2/X2_mag;
+    return vtkm::Abs(vtkm::Dot(x1,x2));
+
+}
+
+} // exec
+} // vtkm
+
+#endif vtk_m_exec_CellSkew_Metric_h
+