401a60b74a
git-svn-id: https://reactphysics3d.googlecode.com/svn/trunk@461 92aac97c-a6ce-11dd-a772-7fcde58d38e6
109 lines
5.9 KiB
C++
109 lines
5.9 KiB
C++
/********************************************************************************
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* ReactPhysics3D physics library, http://code.google.com/p/reactphysics3d/ *
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* Copyright (c) 2010-2012 Daniel Chappuis *
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*********************************************************************************
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* *
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* This software is provided 'as-is', without any express or implied warranty. *
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* In no event will the authors be held liable for any damages arising from the *
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* use of this software. *
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* *
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* Permission is granted to anyone to use this software for any purpose, *
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* including commercial applications, and to alter it and redistribute it *
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* freely, subject to the following restrictions: *
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* *
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* 1. The origin of this software must not be misrepresented; you must not claim *
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* that you wrote the original software. If you use this software in a *
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* product, an acknowledgment in the product documentation would be *
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* appreciated but is not required. *
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* *
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* 2. Altered source versions must be plainly marked as such, and must not be *
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* misrepresented as being the original software. *
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* *
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* 3. This notice may not be removed or altered from any source distribution. *
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* *
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********************************************************************************/
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#ifndef EPA_ALGORITHM_H
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#define EPA_ALGORITHM_H
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// Libraries
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#include "../GJK/Simplex.h"
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#include "../../../colliders/Collider.h"
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#include "../../ContactInfo.h"
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#include "../../../mathematics/mathematics.h"
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#include "TriangleEPA.h"
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#include <algorithm>
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// ReactPhysics3D namespace
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namespace reactphysics3d {
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// Constants
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const unsigned int MAX_SUPPORT_POINTS = 100; // Maximum number of support points of the polytope
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const unsigned int MAX_FACETS = 200; // Maximum number of facets of the polytope
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// Class TriangleComparison that allow the comparison of two triangles in the heap
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// The comparison between two triangles is made using their square distance to the closest
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// point to the origin. The goal is that in the heap, the first triangle is the one with the
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// smallest square distance.
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class TriangleComparison {
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public:
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// Comparison operator
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bool operator()(const TriangleEPA* face1, const TriangleEPA* face2) {
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return (face1->getDistSquare() > face2->getDistSquare());
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}
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};
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/* -------------------------------------------------------------------
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Class EPAAlgorithm :
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This class is the implementation of the Expanding Polytope Algorithm (EPA).
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The EPA algorithm computes the penetration depth and contact points between
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two enlarged objects (with margin) where the original objects (without margin)
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intersect. The penetration depth of a pair of intersecting objects A and B is
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the length of a point on the boundary of the Minkowski sum (A-B) closest to the
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origin. The goal of the EPA algorithm is to start with an initial simplex polytope
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that contains the origin and expend it in order to find the point on the boundary
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of (A-B) that is closest to the origin. An initial simplex that contains origin
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has been computed wit GJK algorithm. The EPA Algorithm will extend this simplex
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polytope to find the correct penetration depth. The implementation of the EPA
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algorithm is based on the book "Collision Detection in 3D Environments".
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-------------------------------------------------------------------
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*/
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class EPAAlgorithm {
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private:
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TriangleComparison triangleComparison; // Triangle comparison operator
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void addFaceCandidate(TriangleEPA* triangle, TriangleEPA** heap,
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uint& nbTriangles, decimal upperBoundSquarePenDepth); // Add a triangle face in the candidate triangle heap
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int isOriginInTetrahedron(const Vector3& p1, const Vector3& p2,
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const Vector3& p3, const Vector3& p4) const; // Decide if the origin is in the tetrahedron
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public:
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EPAAlgorithm(); // Constructor
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~EPAAlgorithm(); // Destructor
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bool computePenetrationDepthAndContactPoints(Simplex simplex, const Collider* collider1, const Transform& transform1,
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const Collider* collider2, const Transform& transform2,
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Vector3& v, ContactInfo*& contactInfo); // Compute the penetration depth with EPA algorithm
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};
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// Add a triangle face in the candidate triangle heap in the EPA algorithm
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inline void EPAAlgorithm::addFaceCandidate(TriangleEPA* triangle, TriangleEPA** heap,
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uint& nbTriangles, decimal upperBoundSquarePenDepth) {
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// If the closest point of the affine hull of triangle points is internal to the triangle and
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// if the distance of the closest point from the origin is at most the penetration depth upper bound
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if (triangle->isClosestPointInternalToTriangle() && triangle->getDistSquare() <= upperBoundSquarePenDepth) {
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// Add the triangle face to the list of candidates
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heap[nbTriangles] = triangle;
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nbTriangles++;
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std::push_heap(&heap[0], &heap[nbTriangles], triangleComparison);
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}
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}
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} // End of ReactPhysics3D namespace
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#endif
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