fuchsia / third_party / eigen / bc25605ec2d13f9bd386b3d697d23d896d4c3a7b / . / unsupported / Eigen / BVH

// This file is part of Eigen, a lightweight C++ template library | |

// for linear algebra. | |

// | |

// Copyright (C) 2009 Ilya Baran <ibaran@mit.edu> | |

// | |

// This Source Code Form is subject to the terms of the Mozilla | |

// Public License v. 2.0. If a copy of the MPL was not distributed | |

// with this file, You can obtain one at http://mozilla.org/MPL/2.0/. | |

#ifndef EIGEN_BVH_MODULE_H | |

#define EIGEN_BVH_MODULE_H | |

#include <Eigen/Core> | |

#include <Eigen/Geometry> | |

#include <Eigen/StdVector> | |

#include <algorithm> | |

#include <queue> | |

namespace Eigen { | |

/** | |

* \defgroup BVH_Module BVH module | |

* \brief This module provides generic bounding volume hierarchy algorithms | |

* and reference tree implementations. | |

* | |

* | |

* \code | |

* #include <unsupported/Eigen/BVH> | |

* \endcode | |

* | |

* A bounding volume hierarchy (BVH) can accelerate many geometric queries. This module provides a generic implementation | |

* of the two basic algorithms over a BVH: intersection of a query object against all objects in the hierarchy and minimization | |

* of a function over the objects in the hierarchy. It also provides intersection and minimization over a cartesian product of | |

* two BVH's. A BVH accelerates intersection by using the fact that if a query object does not intersect a volume, then it cannot | |

* intersect any object contained in that volume. Similarly, a BVH accelerates minimization because the minimum of a function | |

* over a volume is no greater than the minimum of a function over any object contained in it. | |

* | |

* Some sample queries that can be written in terms of intersection are: | |

* - Determine all points where a ray intersects a triangle mesh | |

* - Given a set of points, determine which are contained in a query sphere | |

* - Given a set of spheres, determine which contain the query point | |

* - Given a set of disks, determine if any is completely contained in a query rectangle (represent each 2D disk as a point \f$(x,y,r)\f$ | |

* in 3D and represent the rectangle as a pyramid based on the original rectangle and shrinking in the \f$r\f$ direction) | |

* - 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 | |

* of points with itself) | |

* | |

* Some sample queries that can be written in terms of function minimization over a set of objects are: | |

* - Find the intersection between a ray and a triangle mesh closest to the ray origin (function is infinite off the ray) | |

* - Given a polyline and a query point, determine the closest point on the polyline to the query | |

* - Find the diameter of a point cloud (done by looking at the cartesian product and using negative distance as the function) | |

* - Determine how far two meshes are from colliding (this is also a cartesian product query) | |

* | |

* This implementation decouples the basic algorithms both from the type of hierarchy (and the types of the bounding volumes) and | |

* from the particulars of the query. To enable abstraction from the BVH, the BVH is required to implement a generic mechanism | |

* for traversal. To abstract from the query, the query is responsible for keeping track of results. | |

* | |

* To be used in the algorithms, a hierarchy must implement the following traversal mechanism (see KdBVH for a sample implementation): \code | |

typedef Volume //the type of bounding volume | |

typedef Object //the type of object in the hierarchy | |

typedef Index //a reference to a node in the hierarchy--typically an int or a pointer | |

typedef VolumeIterator //an iterator type over node children--returns Index | |

typedef ObjectIterator //an iterator over object (leaf) children--returns const Object & | |

Index getRootIndex() const //returns the index of the hierarchy root | |

const Volume &getVolume(Index index) const //returns the bounding volume of the node at given index | |

void getChildren(Index index, VolumeIterator &outVBegin, VolumeIterator &outVEnd, | |

ObjectIterator &outOBegin, ObjectIterator &outOEnd) const | |

//getChildren takes a node index and makes [outVBegin, outVEnd) range over its node children | |

//and [outOBegin, outOEnd) range over its object children | |

\endcode | |

* | |

* To use the hierarchy, call BVIntersect or BVMinimize, passing it a BVH (or two, for cartesian product) and a minimizer or intersector. | |

* For an intersection query on a single BVH, the intersector encapsulates the query and must provide two functions: | |

* \code | |

bool intersectVolume(const Volume &volume) //returns true if the query intersects the volume | |

bool intersectObject(const Object &object) //returns true if the intersection search should terminate immediately | |

\endcode | |

* The guarantee that BVIntersect provides is that intersectObject will be called on every object whose bounding volume | |

* intersects the query (but possibly on other objects too) unless the search is terminated prematurely. It is the | |

* responsibility of the intersectObject function to keep track of the results in whatever manner is appropriate. | |

* The cartesian product intersection and the BVMinimize queries are similar--see their individual documentation. | |

* | |

* 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: | |

* \include BVH_Example.cpp | |

* Output: \verbinclude BVH_Example.out | |

*/ | |

} | |

//@{ | |

#include "src/BVH/BVAlgorithms.h" | |

#include "src/BVH/KdBVH.h" | |

//@} | |

#endif // EIGEN_BVH_MODULE_H |