mirror of https://github.com/mosra/magnum.git
Vladimír Vondruš
6 years ago
7 changed files with 280 additions and 18 deletions
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/*
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This file is part of Magnum. |
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Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019 |
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Vladimír Vondruš <mosra@centrum.cz> |
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Permission is hereby granted, free of charge, to any person obtaining a |
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copy of this software and associated documentation files (the "Software"), |
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to deal in the Software without restriction, including without limitation |
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the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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and/or sell copies of the Software, and to permit persons to whom the |
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Software is furnished to do so, subject to the following conditions: |
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The above copyright notice and this permission notice shall be included |
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in all copies or substantial portions of the Software. |
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
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FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
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DEALINGS IN THE SOFTWARE. |
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*/ |
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#include <cstring> |
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#include <Corrade/Containers/StridedArrayView.h> |
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#include <Corrade/Utility/Algorithms.h> |
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#include "RemoveDuplicates.h" |
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namespace Magnum { namespace MeshTools { |
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struct ArrayEqual { |
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bool operator()(Containers::ArrayView<const char> a, Containers::ArrayView<const char> b) const { |
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CORRADE_INTERNAL_ASSERT(a.size() == b.size()); |
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return std::memcmp(a, b, a.size()) == 0; |
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} |
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}; |
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struct ArrayHash { |
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std::size_t operator()(Containers::ArrayView<const char> a) const { |
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return *reinterpret_cast<const std::size_t*>(Utility::MurmurHash2{}(a, a.size()).byteArray()); |
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} |
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}; |
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std::pair<Containers::Array<UnsignedInt>, std::size_t> removeDuplicatesInPlace(const Containers::StridedArrayView2D<char>& data) { |
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/* Assuming the second dimension is contiguous so we can calculate the
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hashes easily */ |
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CORRADE_ASSERT(data.empty()[0] || data.isContiguous<1>(), |
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"MeshTools::removeDuplicatesInPlace(): second data view dimension is not contiguous", {}); |
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const std::size_t dataSize = data.size()[0]; |
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/* Table containing index of first occurence for each unique entry.
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Reserving more buckets than necessary (i.e. as if each entry was |
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unique). */ |
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std::unordered_map<Containers::ArrayView<const char>, UnsignedInt, ArrayHash, ArrayEqual> table{dataSize}; |
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Containers::Array<UnsignedInt> remapping{Containers::NoInit, dataSize}; |
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/* Go through all entries */ |
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for(std::size_t i = 0; i != dataSize; ++i) { |
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/* Try to insert new entry into the table */ |
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const Containers::ArrayView<const char> entry = data[i].asContiguous(); |
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const auto result = table.emplace(entry, table.size()); |
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/* Add the (either new or already existing) index into the array */ |
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remapping[i] = result.first->second; |
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/* If this is a new combination, copy the data to new (earlier)
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position in the array. Data in [table.size()-1, i) are already |
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present in the [0, table.size()-1) range from previous iterations so |
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we aren't overwriting anything. */ |
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if(result.second && i != table.size() - 1) |
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Utility::copy(entry, data[table.size() - 1].asContiguous()); |
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} |
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CORRADE_INTERNAL_ASSERT(dataSize >= table.size()); |
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return {std::move(remapping), table.size()}; |
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} |
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namespace { |
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template<class IndexType> std::size_t removeDuplicatesIndexedInPlaceImplementation(const Containers::StridedArrayView1D<IndexType>& indices, const Containers::StridedArrayView2D<char>& data) { |
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/* Somehow ~IndexType{} doesn't work for < 4byte types, as the result is
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int(-1) instead of the type I want */ |
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CORRADE_ASSERT(data.size()[0] <= IndexType(-1), |
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"MeshTools::removeDuplicatesIndexedInPlace(): a" << sizeof(IndexType) << Debug::nospace << "-byte index type is too small for" << data.size()[0] << "vertices", {}); |
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/* There's no way to avoid the additional allocation, unfortunately ---
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iterating over the indices instead of data would not preserve the |
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original order, which is an useful property. The float version has this |
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inverted (having the *Indexed() variant as the main implementation) |
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because the remapping there has to be done once for every dimension. */ |
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std::pair<Containers::Array<UnsignedInt>, std::size_t> result = removeDuplicatesInPlace(data); |
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for(auto& i: indices) i = result.first[i]; |
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return result.second; |
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} |
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} |
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std::size_t removeDuplicatesIndexedInPlace(const Containers::StridedArrayView1D<UnsignedInt>& indices, const Containers::StridedArrayView2D<char>& data) { |
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return removeDuplicatesIndexedInPlaceImplementation(indices, data); |
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} |
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std::size_t removeDuplicatesIndexedInPlace(const Containers::StridedArrayView1D<UnsignedShort>& indices, const Containers::StridedArrayView2D<char>& data) { |
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return removeDuplicatesIndexedInPlaceImplementation(indices, data); |
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} |
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std::size_t removeDuplicatesIndexedInPlace(const Containers::StridedArrayView1D<UnsignedByte>& indices, const Containers::StridedArrayView2D<char>& data) { |
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return removeDuplicatesIndexedInPlaceImplementation(indices, data); |
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} |
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}} |
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