63 lines
2.2 KiB
C++
63 lines
2.2 KiB
C++
// This file is part of libigl, a simple c++ geometry processing library.
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//
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// Copyright (C) 2018 Gavin Barill <gavinpcb@gmail.com>
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//
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// This Source Code Form is subject to the terms of the Mozilla Public License
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// v. 2.0. If a copy of the MPL was not distributed with this file, You can
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// obtain one at http://mozilla.org/MPL/2.0/
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#ifndef IGL_OCTREE
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#define IGL_OCTREE
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#include "igl_inline.h"
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#include <Eigen/Core>
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#include <vector>
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namespace igl
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{
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// Given a set of 3D points P, generate data structures for a pointerless
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// octree. Each cell stores its points, children, center location and width.
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// Our octree is not dense. We use the following rule: if the current cell
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// has any number of points, it will have all 8 children. A leaf cell will
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// have -1's as its list of child indices.
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//
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// We use a binary numbering of children. Treating the parent cell's center
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// as the origin, we number the octants in the following manner:
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// The first bit is 1 iff the octant's x coordinate is positive
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// The second bit is 1 iff the octant's y coordinate is positive
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// The third bit is 1 iff the octant's z coordinate is positive
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//
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// For example, the octant with negative x, positive y, positive z is:
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// 110 binary = 6 decimal
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//
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// Inputs:
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// P #P by 3 list of point locations
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//
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// Outputs:
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// point_indices a vector of vectors, where the ith entry is a vector of
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// the indices into P that are the ith octree cell's points
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// CH #OctreeCells by 8, where the ith row is the indices of
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// the ith octree cell's children
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// CN #OctreeCells by 3, where the ith row is a 3d row vector
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// representing the position of the ith cell's center
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// W #OctreeCells, a vector where the ith entry is the width
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// of the ith octree cell
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//
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template <typename DerivedP, typename IndexType, typename DerivedCH,
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typename DerivedCN, typename DerivedW>
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IGL_INLINE void octree(const Eigen::MatrixBase<DerivedP>& P,
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std::vector<std::vector<IndexType> > & point_indices,
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Eigen::PlainObjectBase<DerivedCH>& CH,
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Eigen::PlainObjectBase<DerivedCN>& CN,
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Eigen::PlainObjectBase<DerivedW>& W);
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}
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#ifndef IGL_STATIC_LIBRARY
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# include "octree.cpp"
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#endif
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#endif
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