148 lines
5.5 KiB
C++
148 lines
5.5 KiB
C++
//============================================================================
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// Copyright (c) Kitware, Inc.
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// All rights reserved.
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// See LICENSE.txt for details.
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//
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// This software is distributed WITHOUT ANY WARRANTY; without even
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// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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// PURPOSE. See the above copyright notice for more information.
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//============================================================================
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#ifndef vtk_m_exec_FieldNeighborhood_h
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#define vtk_m_exec_FieldNeighborhood_h
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#include <vtkm/exec/BoundaryState.h>
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#include <vtkm/internal/ArrayPortalUniformPointCoordinates.h>
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namespace vtkm
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{
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namespace exec
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{
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/// @brief Retrieves field values from a neighborhood.
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///
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/// `FieldNeighborhood` manages the retrieval of field values within the neighborhood of a
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/// `vtkm::worklet::WorkletPointNeighborhood` worklet. The `Get` methods take ijk indices
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/// relative to the neighborhood (with 0, 0, 0 being the element visted) and return the
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/// field value at that part of the neighborhood. If the requested neighborhood is outside
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/// the boundary, the value at the nearest boundary will be returned. A `vtkm::exec::BoundaryState`
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/// object can be used to determine if the neighborhood extends beyond the boundary of the mesh.
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///
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/// This class is typically constructed using the `FieldInNeighborhood` tag in an
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/// `ExecutionSignature`. There is little reason to construct this in user code.
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///
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template <typename FieldPortalType>
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struct FieldNeighborhood
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{
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VTKM_EXEC
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FieldNeighborhood(const FieldPortalType& portal, const vtkm::exec::BoundaryState& boundary)
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: Boundary(&boundary)
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, Portal(portal)
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{
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}
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using ValueType = typename FieldPortalType::ValueType;
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/// @brief Retrieve a field value relative to the visited element.
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///
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/// The index is given as three dimensional i, j, k indices. These indices are relative
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/// to the currently visited element. So, calling `Get(0, 0, 0)` retrieves the field
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/// value at the visited element. Calling `Get(-1, 0, 0)` retrieves the value to the
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/// "left" and `Get(1, 0, 0)` retrieves the value to the "right."
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///
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/// If the relative index points outside the bounds of the mesh, `Get` will return the
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/// value closest to the boundary (i.e. clamping behvior). For example, if the visited
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/// element is at the leftmost index of the mesh, `Get(-1, 0, 0)` will refer to a value
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/// outside the bounds of the mesh. In this case, `Get` will return the value at the
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/// visited index, which is the closest element at that boundary.
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///
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/// When referring to values in a mesh of less than 3 dimensions (such as a 2D structured),
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/// simply use 0 for the unused dimensions.
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VTKM_EXEC
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ValueType Get(vtkm::IdComponent i, vtkm::IdComponent j, vtkm::IdComponent k) const
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{
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return Portal.Get(this->Boundary->NeighborIndexToFlatIndexClamp(i, j, k));
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}
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/// @brief Retrieve a field value relative to the visited element without bounds checking.
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///
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/// `GetUnchecked` behaves the same as `Get` except that no bounds checking is done
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/// before retrieving the field value. If the relative index is out of bounds of the
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/// mesh, the results are undefined.
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///
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/// `GetUnchecked` is useful in circumstances where the bounds have already be checked.
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/// This prevents wasting time repeating checks.
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VTKM_EXEC
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ValueType GetUnchecked(vtkm::IdComponent i, vtkm::IdComponent j, vtkm::IdComponent k) const
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{
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return Portal.Get(this->Boundary->NeighborIndexToFlatIndex(i, j, k));
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}
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/// @copydoc Get
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VTKM_EXEC
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ValueType Get(const vtkm::Id3& ijk) const
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{
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return Portal.Get(this->Boundary->NeighborIndexToFlatIndexClamp(ijk));
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}
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/// @copydoc GetUnchecked
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VTKM_EXEC
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ValueType GetUnchecked(const vtkm::Id3& ijk) const
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{
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return Portal.Get(this->Boundary->NeighborIndexToFlatIndex(ijk));
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}
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/// The `vtkm::exec::BoundaryState` used to find field values from local indices.
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vtkm::exec::BoundaryState const* const Boundary;
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/// The array portal containing field values.
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FieldPortalType Portal;
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};
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/// \brief Specialization of Neighborhood for ArrayPortalUniformPointCoordinates
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/// We can use fast paths inside ArrayPortalUniformPointCoordinates to allow
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/// for very fast computation of the coordinates reachable by the neighborhood
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template <>
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struct FieldNeighborhood<vtkm::internal::ArrayPortalUniformPointCoordinates>
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{
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VTKM_EXEC
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FieldNeighborhood(const vtkm::internal::ArrayPortalUniformPointCoordinates& portal,
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const vtkm::exec::BoundaryState& boundary)
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: Boundary(&boundary)
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, Portal(portal)
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{
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}
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using ValueType = vtkm::internal::ArrayPortalUniformPointCoordinates::ValueType;
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VTKM_EXEC
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ValueType Get(vtkm::IdComponent i, vtkm::IdComponent j, vtkm::IdComponent k) const
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{
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return Portal.Get(this->Boundary->NeighborIndexToFullIndexClamp(i, j, k));
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}
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VTKM_EXEC
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ValueType GetUnchecked(vtkm::IdComponent i, vtkm::IdComponent j, vtkm::IdComponent k) const
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{
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return Portal.Get(this->Boundary->NeighborIndexToFullIndex(i, j, k));
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}
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VTKM_EXEC
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ValueType Get(const vtkm::IdComponent3& ijk) const
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{
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return Portal.Get(this->Boundary->NeighborIndexToFullIndexClamp(ijk));
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}
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VTKM_EXEC
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ValueType GetUnchecked(const vtkm::IdComponent3& ijk) const
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{
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return Portal.Get(this->Boundary->NeighborIndexToFullIndex(ijk));
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}
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vtkm::exec::BoundaryState const* const Boundary;
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vtkm::internal::ArrayPortalUniformPointCoordinates Portal;
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};
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}
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} // namespace vtkm::exec
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#endif //vtk_m_exec_FieldNeighborhood_h
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