96 lines
5.4 KiB
Plaintext
96 lines
5.4 KiB
Plaintext
// This file is part of Eigen, a lightweight C++ template library
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// for linear algebra.
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//
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// Copyright (C) 2009 Ilya Baran <ibaran@mit.edu>
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//
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// This Source Code Form is subject to the terms of the Mozilla
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// Public License v. 2.0. If a copy of the MPL was not distributed
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// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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#ifndef EIGEN_BVH_MODULE_H
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#define EIGEN_BVH_MODULE_H
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#include <Eigen/Core>
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#include <Eigen/Geometry>
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#include <Eigen/StdVector>
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#include <algorithm>
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#include <queue>
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namespace Eigen {
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/**
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* \defgroup BVH_Module BVH module
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* \brief This module provides generic bounding volume hierarchy algorithms
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* and reference tree implementations.
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*
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*
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* \code
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* #include <unsupported/Eigen/BVH>
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* \endcode
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*
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* A bounding volume hierarchy (BVH) can accelerate many geometric queries. This module provides a generic implementation
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* of the two basic algorithms over a BVH: intersection of a query object against all objects in the hierarchy and minimization
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* of a function over the objects in the hierarchy. It also provides intersection and minimization over a cartesian product of
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* two BVH's. A BVH accelerates intersection by using the fact that if a query object does not intersect a volume, then it cannot
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* intersect any object contained in that volume. Similarly, a BVH accelerates minimization because the minimum of a function
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* over a volume is no greater than the minimum of a function over any object contained in it.
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*
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* Some sample queries that can be written in terms of intersection are:
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* - Determine all points where a ray intersects a triangle mesh
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* - Given a set of points, determine which are contained in a query sphere
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* - Given a set of spheres, determine which contain the query point
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* - Given a set of disks, determine if any is completely contained in a query rectangle (represent each 2D disk as a point \f$(x,y,r)\f$
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* in 3D and represent the rectangle as a pyramid based on the original rectangle and shrinking in the \f$r\f$ direction)
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* - Given a set of points, count how many pairs are \f$d\pm\epsilon\f$ apart (done by looking at the cartesian product of the set
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* of points with itself)
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*
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* Some sample queries that can be written in terms of function minimization over a set of objects are:
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* - Find the intersection between a ray and a triangle mesh closest to the ray origin (function is infinite off the ray)
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* - Given a polyline and a query point, determine the closest point on the polyline to the query
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* - Find the diameter of a point cloud (done by looking at the cartesian product and using negative distance as the function)
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* - Determine how far two meshes are from colliding (this is also a cartesian product query)
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*
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* This implementation decouples the basic algorithms both from the type of hierarchy (and the types of the bounding volumes) and
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* from the particulars of the query. To enable abstraction from the BVH, the BVH is required to implement a generic mechanism
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* for traversal. To abstract from the query, the query is responsible for keeping track of results.
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*
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* To be used in the algorithms, a hierarchy must implement the following traversal mechanism (see KdBVH for a sample implementation): \code
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typedef Volume //the type of bounding volume
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typedef Object //the type of object in the hierarchy
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typedef Index //a reference to a node in the hierarchy--typically an int or a pointer
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typedef VolumeIterator //an iterator type over node children--returns Index
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typedef ObjectIterator //an iterator over object (leaf) children--returns const Object &
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Index getRootIndex() const //returns the index of the hierarchy root
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const Volume &getVolume(Index index) const //returns the bounding volume of the node at given index
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void getChildren(Index index, VolumeIterator &outVBegin, VolumeIterator &outVEnd,
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ObjectIterator &outOBegin, ObjectIterator &outOEnd) const
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//getChildren takes a node index and makes [outVBegin, outVEnd) range over its node children
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//and [outOBegin, outOEnd) range over its object children
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\endcode
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*
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* To use the hierarchy, call BVIntersect or BVMinimize, passing it a BVH (or two, for cartesian product) and a minimizer or intersector.
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* For an intersection query on a single BVH, the intersector encapsulates the query and must provide two functions:
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* \code
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bool intersectVolume(const Volume &volume) //returns true if the query intersects the volume
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bool intersectObject(const Object &object) //returns true if the intersection search should terminate immediately
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\endcode
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* The guarantee that BVIntersect provides is that intersectObject will be called on every object whose bounding volume
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* intersects the query (but possibly on other objects too) unless the search is terminated prematurely. It is the
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* responsibility of the intersectObject function to keep track of the results in whatever manner is appropriate.
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* The cartesian product intersection and the BVMinimize queries are similar--see their individual documentation.
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*
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* The following is a simple but complete example for how to use the BVH to accelerate the search for a closest red-blue point pair:
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* \include BVH_Example.cpp
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* Output: \verbinclude BVH_Example.out
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*/
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}
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//@{
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#include "src/BVH/BVAlgorithms.h"
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#include "src/BVH/KdBVH.h"
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//@}
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#endif // EIGEN_BVH_MODULE_H
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