mirror of
https://gitlab.kitware.com/vtk/vtk-m
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117 lines
5.1 KiB
C++
117 lines
5.1 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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// Copyright (c) 2016, Los Alamos National Security, LLC
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// All rights reserved.
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//
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// Copyright 2016. Los Alamos National Security, LLC.
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// This software was produced under U.S. Government contract DE-AC52-06NA25396
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// for Los Alamos National Laboratory (LANL), which is operated by
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// Los Alamos National Security, LLC for the U.S. Department of Energy.
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// The U.S. Government has rights to use, reproduce, and distribute this
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// software. NEITHER THE GOVERNMENT NOR LOS ALAMOS NATIONAL SECURITY, LLC
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// MAKES ANY WARRANTY, EXPRESS OR IMPLIED, OR ASSUMES ANY LIABILITY FOR THE
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// USE OF THIS SOFTWARE. If software is modified to produce derivative works,
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// such modified software should be clearly marked, so as not to confuse it
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// with the version available from LANL.
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//
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// Additionally, redistribution and use in source and binary forms, with or
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// without modification, are permitted provided that the following conditions
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// are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// 3. Neither the name of Los Alamos National Security, LLC, Los Alamos
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// National Laboratory, LANL, the U.S. Government, nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY LOS ALAMOS NATIONAL SECURITY, LLC AND
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// CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
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// BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL LOS ALAMOS
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// NATIONAL SECURITY, LLC OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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// USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//============================================================================
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// This code is based on the algorithm presented in the paper:
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// “Parallel Peak Pruning for Scalable SMP Contour Tree Computation.”
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// Hamish Carr, Gunther Weber, Christopher Sewell, and James Ahrens.
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// Proceedings of the IEEE Symposium on Large Data Analysis and Visualization
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// (LDAV), October 2016, Baltimore, Maryland.
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//=======================================================================================
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//
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// COMMENTS:
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//
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// This functor implements chain-doubling (pointer-doubling), but minimises memory writeback
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// by testing whether we've hit the end of the chain already
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//
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// Any vector needed by the functor for lookup purposes will be passed as a parameter to
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// the constructor and saved, with the actual function call being the operator ()
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//
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// Vectors marked I/O are intrinsically risky unless there is an algorithmic guarantee
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// that the read/writes are completely independent - which for our case actually occurs
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// The I/O vectors should therefore be justified in comments both here & in caller
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//
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//=======================================================================================
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#ifndef vtkm_worklet_contourtree_chain_doubler_h
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#define vtkm_worklet_contourtree_chain_doubler_h
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#include <vtkm/worklet/WorkletMapField.h>
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namespace vtkm
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{
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namespace worklet
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{
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namespace contourtree
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{
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// Functor for doing chain doubling
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// Unary because it takes the index of the element to process, and is not guaranteed to
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// write back
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// moreover, we aren't worried about out-of-sequence writes, since the worst that happens
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// is that an element gets pointer-tripled in the iteration. It will still converge to the
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// same destination.
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class ChainDoubler : public vtkm::worklet::WorkletMapField
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{
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public:
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using ControlSignature = void(FieldIn vertexID, WholeArrayInOut chains);
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using ExecutionSignature = void(_1, _2);
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using InputDomain = _1;
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// Constructor
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VTKM_EXEC_CONT
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ChainDoubler() {}
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template <typename InOutFieldPortalType>
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VTKM_EXEC void operator()(const vtkm::Id& vertexID, const InOutFieldPortalType& chains) const
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{
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vtkm::Id next = chains.Get(vertexID);
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vtkm::Id doubleNext = chains.Get(next);
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if (next != doubleNext)
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chains.Set(vertexID, doubleNext);
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}
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}; // ChainDoubler
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}
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}
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}
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#endif
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