vtk-m2/vtkm/filter/Gradient.hxx

//============================================================================
//  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 Sandia Corporation.
//  Copyright 2014 UT-Battelle, LLC.
//  Copyright 2014 Los Alamos National Security.
//
//  Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
//  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.
//============================================================================

#include <vtkm/cont/DynamicCellSet.h>

#include <vtkm/worklet/DispatcherMapTopology.h>

#include <vtkm/worklet/Gradient.h>

namespace
{

//-----------------------------------------------------------------------------
template <typename DerivedPolicy, typename Device, typename T, typename S>
struct PointGrad
{
  PointGrad(const vtkm::cont::CoordinateSystem& coords,
            const vtkm::cont::ArrayHandle<T, S>& field,
            vtkm::cont::ArrayHandle<vtkm::Vec<T, 3>>* result)
    : Points(&coords)
    , InField(&field)
    , Result(result)
  {
  }

  template <typename CellSetType>
  void operator()(const CellSetType& cellset) const
  {
    vtkm::worklet::DispatcherMapTopology<vtkm::worklet::PointGradient, Device> dispatcher;
    dispatcher.Invoke(cellset, //topology to iterate on a per point basis
                      cellset, //whole cellset in
                      vtkm::filter::ApplyPolicy(*this->Points, this->Policy),
                      *this->InField,
                      *this->Result);
  }

  vtkm::filter::PolicyBase<DerivedPolicy> Policy;
  const vtkm::cont::CoordinateSystem* const Points;
  const vtkm::cont::ArrayHandle<T, S>* const InField;
  vtkm::cont::ArrayHandle<vtkm::Vec<T, 3>>* Result;

private:
  void operator=(const PointGrad<DerivedPolicy, Device, T, S>&) = delete;
};

//-----------------------------------------------------------------------------
template <typename HandleType>
inline void add_field(vtkm::filter::ResultField& result,
                      const HandleType& handle,
                      const std::string name)
{
  const vtkm::cont::Field::AssociationEnum assoc = result.GetField().GetAssociation();
  if ((assoc == vtkm::cont::Field::ASSOC_WHOLE_MESH) || (assoc == vtkm::cont::Field::ASSOC_POINTS))
  {
    vtkm::cont::Field field(name, assoc, handle);
    result.GetDataSet().AddField(field);
  }
  else
  {
    vtkm::cont::Field field(name, assoc, result.GetField().GetAssocCellSet(), handle);
    result.GetDataSet().AddField(field);
  }
}

//-----------------------------------------------------------------------------
template <typename T, typename S, typename DeviceAdapter>
inline void add_extra_vec_fields(
  const vtkm::cont::ArrayHandle<vtkm::Vec<vtkm::Vec<T, 3>, 3>, S>& inField,
  const vtkm::filter::Gradient* const filter,
  vtkm::filter::ResultField& result,
  const DeviceAdapter&)
{
  if (filter->GetComputeDivergence())
  {
    vtkm::cont::ArrayHandle<T> divergence;
    vtkm::worklet::DispatcherMapField<vtkm::worklet::Divergence, DeviceAdapter> dispatcher;
    dispatcher.Invoke(inField, divergence);

    add_field(result, divergence, filter->GetDivergenceName());
  }

  if (filter->GetComputeVorticity())
  {
    vtkm::cont::ArrayHandle<vtkm::Vec<T, 3>> vorticity;
    vtkm::worklet::DispatcherMapField<vtkm::worklet::Vorticity, DeviceAdapter> dispatcher;
    dispatcher.Invoke(inField, vorticity);

    add_field(result, vorticity, filter->GetVorticityName());
  }

  if (filter->GetComputeQCriterion())
  {
    vtkm::cont::ArrayHandle<T> qc;
    vtkm::worklet::DispatcherMapField<vtkm::worklet::QCriterion, DeviceAdapter> dispatcher;
    dispatcher.Invoke(inField, qc);

    add_field(result, qc, filter->GetQCriterionName());
  }
}

template <typename T, typename S, typename DeviceAdapter>
inline void add_extra_vec_fields(const vtkm::cont::ArrayHandle<T, S>&,
                                 const vtkm::filter::Gradient* const,
                                 vtkm::filter::ResultField&,
                                 const DeviceAdapter&)
{
  //not a vector array handle so add nothing
}

} //namespace

namespace vtkm
{
namespace filter
{

//-----------------------------------------------------------------------------
Gradient::Gradient()
  : ComputePointGradient(false)
  , ComputeVorticity(false)
  , ComputeQCriterion(false)
  , DivergenceName("Divergence")
  , VorticityName("Vorticity")
  , QCriterionName("QCriterion")
{
}

//-----------------------------------------------------------------------------
template <typename T, typename StorageType, typename DerivedPolicy, typename DeviceAdapter>
inline vtkm::filter::ResultField Gradient::DoExecute(
  const vtkm::cont::DataSet& input,
  const vtkm::cont::ArrayHandle<T, StorageType>& inField,
  const vtkm::filter::FieldMetadata& fieldMetadata,
  const vtkm::filter::PolicyBase<DerivedPolicy>& policy,
  const DeviceAdapter& adapter)
{
  if (!fieldMetadata.IsPointField())
  {
    //we currently only support point fields, as we need to write the
    //worklet to efficiently map a cell field to the points of a cell
    //without doing a memory explosion
    return vtkm::filter::ResultField();
  }

  const vtkm::cont::DynamicCellSet& cells = input.GetCellSet(this->GetActiveCellSetIndex());
  const vtkm::cont::CoordinateSystem& coords =
    input.GetCoordinateSystem(this->GetActiveCoordinateSystemIndex());

  vtkm::cont::Field::AssociationEnum fieldAssociation;
  std::string outputName = this->GetOutputFieldName();
  if (outputName.empty())
  {
    outputName = "Gradients";
  }

  //todo: we need to ask the policy what storage type we should be using
  //If the input is implicit, we should know what to fall back to
  vtkm::cont::ArrayHandle<vtkm::Vec<T, 3>> outArray;
  if (this->ComputePointGradient)
  {
    PointGrad<DerivedPolicy, DeviceAdapter, T, StorageType> func(coords, inField, &outArray);
    vtkm::cont::CastAndCall(vtkm::filter::ApplyPolicy(cells, policy), func);
    fieldAssociation = vtkm::cont::Field::ASSOC_POINTS;
  }
  else
  {
    vtkm::worklet::DispatcherMapTopology<vtkm::worklet::CellGradient, DeviceAdapter> dispatcher;
    dispatcher.Invoke(vtkm::filter::ApplyPolicy(cells, policy),
                      vtkm::filter::ApplyPolicy(coords, policy),
                      inField,
                      outArray);
    fieldAssociation = vtkm::cont::Field::ASSOC_CELL_SET;
  }

  vtkm::filter::ResultField result(input, outArray, outputName, fieldAssociation, cells.GetName());

  //Add the vorticity and qcriterion fields if they are enabled to the result
  add_extra_vec_fields(outArray, this, result, adapter);

  return result;
}
}
} // namespace vtkm::filter