370 lines
14 KiB
C++
370 lines
14 KiB
C++
/*
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Bullet Continuous Collision Detection and Physics Library
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Copyright (c) 2003-2014 Erwin Coumans http://bulletphysics.org
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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 use of this software.
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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 freely,
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subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
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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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#ifndef BT_GJK_EPA_PENETATION_CONVEX_COLLISION_H
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#define BT_GJK_EPA_PENETATION_CONVEX_COLLISION_H
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#include "LinearMath/btTransform.h" // Note that btVector3 might be double precision...
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#include "btGjkEpa3.h"
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#include "btGjkCollisionDescription.h"
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#include "BulletCollision/NarrowPhaseCollision/btVoronoiSimplexSolver.h"
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template <typename btConvexTemplate>
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bool btGjkEpaCalcPenDepth(const btConvexTemplate& a, const btConvexTemplate& b,
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const btGjkCollisionDescription& colDesc,
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btVector3& v, btVector3& wWitnessOnA, btVector3& wWitnessOnB)
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{
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(void)v;
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// const btScalar radialmargin(btScalar(0.));
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btVector3 guessVector(b.getWorldTransform().getOrigin()-a.getWorldTransform().getOrigin());//?? why not use the GJK input?
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btGjkEpaSolver3::sResults results;
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if(btGjkEpaSolver3_Penetration(a,b,guessVector,results))
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{
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// debugDraw->drawLine(results.witnesses[1],results.witnesses[1]+results.normal,btVector3(255,0,0));
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//resultOut->addContactPoint(results.normal,results.witnesses[1],-results.depth);
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wWitnessOnA = results.witnesses[0];
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wWitnessOnB = results.witnesses[1];
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v = results.normal;
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return true;
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} else
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{
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if(btGjkEpaSolver3_Distance(a,b,guessVector,results))
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{
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wWitnessOnA = results.witnesses[0];
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wWitnessOnB = results.witnesses[1];
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v = results.normal;
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return false;
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}
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}
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return false;
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}
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template <typename btConvexTemplate, typename btGjkDistanceTemplate>
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int btComputeGjkEpaPenetration(const btConvexTemplate& a, const btConvexTemplate& b, const btGjkCollisionDescription& colDesc, btVoronoiSimplexSolver& simplexSolver, btGjkDistanceTemplate* distInfo)
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{
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bool m_catchDegeneracies = true;
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btScalar m_cachedSeparatingDistance = 0.f;
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btScalar distance=btScalar(0.);
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btVector3 normalInB(btScalar(0.),btScalar(0.),btScalar(0.));
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btVector3 pointOnA,pointOnB;
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btTransform localTransA = a.getWorldTransform();
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btTransform localTransB = b.getWorldTransform();
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btScalar marginA = a.getMargin();
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btScalar marginB = b.getMargin();
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int m_curIter = 0;
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int gGjkMaxIter = colDesc.m_maxGjkIterations;//this is to catch invalid input, perhaps check for #NaN?
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btVector3 m_cachedSeparatingAxis = colDesc.m_firstDir;
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bool isValid = false;
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bool checkSimplex = false;
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bool checkPenetration = true;
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int m_degenerateSimplex = 0;
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int m_lastUsedMethod = -1;
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{
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btScalar squaredDistance = BT_LARGE_FLOAT;
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btScalar delta = btScalar(0.);
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btScalar margin = marginA + marginB;
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simplexSolver.reset();
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for ( ; ; )
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//while (true)
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{
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btVector3 seperatingAxisInA = (-m_cachedSeparatingAxis)* localTransA.getBasis();
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btVector3 seperatingAxisInB = m_cachedSeparatingAxis* localTransB.getBasis();
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btVector3 pInA = a.getLocalSupportWithoutMargin(seperatingAxisInA);
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btVector3 qInB = b.getLocalSupportWithoutMargin(seperatingAxisInB);
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btVector3 pWorld = localTransA(pInA);
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btVector3 qWorld = localTransB(qInB);
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btVector3 w = pWorld - qWorld;
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delta = m_cachedSeparatingAxis.dot(w);
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// potential exit, they don't overlap
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if ((delta > btScalar(0.0)) && (delta * delta > squaredDistance * colDesc.m_maximumDistanceSquared))
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{
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m_degenerateSimplex = 10;
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checkSimplex=true;
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//checkPenetration = false;
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break;
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}
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//exit 0: the new point is already in the simplex, or we didn't come any closer
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if (simplexSolver.inSimplex(w))
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{
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m_degenerateSimplex = 1;
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checkSimplex = true;
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break;
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}
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// are we getting any closer ?
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btScalar f0 = squaredDistance - delta;
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btScalar f1 = squaredDistance * colDesc.m_gjkRelError2;
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if (f0 <= f1)
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{
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if (f0 <= btScalar(0.))
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{
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m_degenerateSimplex = 2;
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} else
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{
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m_degenerateSimplex = 11;
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}
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checkSimplex = true;
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break;
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}
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//add current vertex to simplex
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simplexSolver.addVertex(w, pWorld, qWorld);
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btVector3 newCachedSeparatingAxis;
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//calculate the closest point to the origin (update vector v)
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if (!simplexSolver.closest(newCachedSeparatingAxis))
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{
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m_degenerateSimplex = 3;
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checkSimplex = true;
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break;
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}
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if(newCachedSeparatingAxis.length2()<colDesc.m_gjkRelError2)
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{
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m_cachedSeparatingAxis = newCachedSeparatingAxis;
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m_degenerateSimplex = 6;
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checkSimplex = true;
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break;
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}
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btScalar previousSquaredDistance = squaredDistance;
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squaredDistance = newCachedSeparatingAxis.length2();
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#if 0
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///warning: this termination condition leads to some problems in 2d test case see Bullet/Demos/Box2dDemo
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if (squaredDistance>previousSquaredDistance)
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{
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m_degenerateSimplex = 7;
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squaredDistance = previousSquaredDistance;
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checkSimplex = false;
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break;
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}
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#endif //
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//redundant m_simplexSolver->compute_points(pointOnA, pointOnB);
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//are we getting any closer ?
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if (previousSquaredDistance - squaredDistance <= SIMD_EPSILON * previousSquaredDistance)
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{
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// m_simplexSolver->backup_closest(m_cachedSeparatingAxis);
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checkSimplex = true;
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m_degenerateSimplex = 12;
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break;
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}
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m_cachedSeparatingAxis = newCachedSeparatingAxis;
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//degeneracy, this is typically due to invalid/uninitialized worldtransforms for a btCollisionObject
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if (m_curIter++ > gGjkMaxIter)
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{
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#if defined(DEBUG) || defined (_DEBUG)
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printf("btGjkPairDetector maxIter exceeded:%i\n",m_curIter);
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printf("sepAxis=(%f,%f,%f), squaredDistance = %f\n",
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m_cachedSeparatingAxis.getX(),
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m_cachedSeparatingAxis.getY(),
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m_cachedSeparatingAxis.getZ(),
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squaredDistance);
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#endif
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break;
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}
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bool check = (!simplexSolver.fullSimplex());
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//bool check = (!m_simplexSolver->fullSimplex() && squaredDistance > SIMD_EPSILON * m_simplexSolver->maxVertex());
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if (!check)
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{
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//do we need this backup_closest here ?
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// m_simplexSolver->backup_closest(m_cachedSeparatingAxis);
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m_degenerateSimplex = 13;
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break;
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}
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}
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if (checkSimplex)
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{
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simplexSolver.compute_points(pointOnA, pointOnB);
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normalInB = m_cachedSeparatingAxis;
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btScalar lenSqr =m_cachedSeparatingAxis.length2();
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//valid normal
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if (lenSqr < 0.0001)
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{
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m_degenerateSimplex = 5;
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}
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if (lenSqr > SIMD_EPSILON*SIMD_EPSILON)
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{
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btScalar rlen = btScalar(1.) / btSqrt(lenSqr );
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normalInB *= rlen; //normalize
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btScalar s = btSqrt(squaredDistance);
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btAssert(s > btScalar(0.0));
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pointOnA -= m_cachedSeparatingAxis * (marginA / s);
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pointOnB += m_cachedSeparatingAxis * (marginB / s);
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distance = ((btScalar(1.)/rlen) - margin);
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isValid = true;
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m_lastUsedMethod = 1;
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} else
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{
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m_lastUsedMethod = 2;
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}
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}
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bool catchDegeneratePenetrationCase =
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(m_catchDegeneracies && m_degenerateSimplex && ((distance+margin) < 0.01));
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//if (checkPenetration && !isValid)
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if (checkPenetration && (!isValid || catchDegeneratePenetrationCase ))
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{
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//penetration case
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//if there is no way to handle penetrations, bail out
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// Penetration depth case.
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btVector3 tmpPointOnA,tmpPointOnB;
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m_cachedSeparatingAxis.setZero();
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bool isValid2 = btGjkEpaCalcPenDepth(a,b,
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colDesc,
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m_cachedSeparatingAxis, tmpPointOnA, tmpPointOnB);
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if (isValid2)
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{
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btVector3 tmpNormalInB = tmpPointOnB-tmpPointOnA;
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btScalar lenSqr = tmpNormalInB.length2();
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if (lenSqr <= (SIMD_EPSILON*SIMD_EPSILON))
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{
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tmpNormalInB = m_cachedSeparatingAxis;
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lenSqr = m_cachedSeparatingAxis.length2();
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}
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if (lenSqr > (SIMD_EPSILON*SIMD_EPSILON))
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{
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tmpNormalInB /= btSqrt(lenSqr);
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btScalar distance2 = -(tmpPointOnA-tmpPointOnB).length();
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//only replace valid penetrations when the result is deeper (check)
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if (!isValid || (distance2 < distance))
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{
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distance = distance2;
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pointOnA = tmpPointOnA;
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pointOnB = tmpPointOnB;
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normalInB = tmpNormalInB;
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isValid = true;
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m_lastUsedMethod = 3;
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} else
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{
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m_lastUsedMethod = 8;
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}
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} else
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{
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m_lastUsedMethod = 9;
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}
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} else
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{
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///this is another degenerate case, where the initial GJK calculation reports a degenerate case
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///EPA reports no penetration, and the second GJK (using the supporting vector without margin)
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///reports a valid positive distance. Use the results of the second GJK instead of failing.
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///thanks to Jacob.Langford for the reproduction case
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///http://code.google.com/p/bullet/issues/detail?id=250
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if (m_cachedSeparatingAxis.length2() > btScalar(0.))
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{
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btScalar distance2 = (tmpPointOnA-tmpPointOnB).length()-margin;
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//only replace valid distances when the distance is less
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if (!isValid || (distance2 < distance))
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{
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distance = distance2;
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pointOnA = tmpPointOnA;
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pointOnB = tmpPointOnB;
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pointOnA -= m_cachedSeparatingAxis * marginA ;
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pointOnB += m_cachedSeparatingAxis * marginB ;
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normalInB = m_cachedSeparatingAxis;
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normalInB.normalize();
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isValid = true;
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m_lastUsedMethod = 6;
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} else
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{
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m_lastUsedMethod = 5;
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}
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}
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}
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}
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}
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if (isValid && ((distance < 0) || (distance*distance < colDesc.m_maximumDistanceSquared)))
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{
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m_cachedSeparatingAxis = normalInB;
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m_cachedSeparatingDistance = distance;
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distInfo->m_distance = distance;
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distInfo->m_normalBtoA = normalInB;
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distInfo->m_pointOnB = pointOnB;
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distInfo->m_pointOnA = pointOnB+normalInB*distance;
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return 0;
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}
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return -m_lastUsedMethod;
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}
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#endif //BT_GJK_EPA_PENETATION_CONVEX_COLLISION_H
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