288 lines
9.5 KiB
C++
288 lines
9.5 KiB
C++
/*
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Bullet Continuous Collision Detection and Physics Library
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btConeTwistConstraint is Copyright (c) 2007 Starbreeze Studios
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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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Written by: Marcus Hennix
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*/
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#include "btConeTwistConstraint.h"
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#include "BulletDynamics/Dynamics/btRigidBody.h"
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#include "LinearMath/btTransformUtil.h"
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#include "LinearMath/btSimdMinMax.h"
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#include <new>
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btConeTwistConstraint::btConeTwistConstraint()
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:btTypedConstraint(CONETWIST_CONSTRAINT_TYPE)
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{
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}
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btConeTwistConstraint::btConeTwistConstraint(btRigidBody& rbA,btRigidBody& rbB,
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const btTransform& rbAFrame,const btTransform& rbBFrame)
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:btTypedConstraint(CONETWIST_CONSTRAINT_TYPE, rbA,rbB),m_rbAFrame(rbAFrame),m_rbBFrame(rbBFrame),
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m_angularOnly(false)
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{
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// flip axis for correct angles
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m_rbBFrame.getBasis()[1][0] *= btScalar(-1.);
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m_rbBFrame.getBasis()[1][1] *= btScalar(-1.);
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m_rbBFrame.getBasis()[1][2] *= btScalar(-1.);
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m_swingSpan1 = btScalar(1e30);
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m_swingSpan2 = btScalar(1e30);
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m_twistSpan = btScalar(1e30);
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m_biasFactor = 0.3f;
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m_relaxationFactor = 1.0f;
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m_solveTwistLimit = false;
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m_solveSwingLimit = false;
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}
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btConeTwistConstraint::btConeTwistConstraint(btRigidBody& rbA,const btTransform& rbAFrame)
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:btTypedConstraint(CONETWIST_CONSTRAINT_TYPE,rbA),m_rbAFrame(rbAFrame),
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m_angularOnly(false)
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{
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m_rbBFrame = m_rbAFrame;
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// flip axis for correct angles
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m_rbBFrame.getBasis()[1][0] *= btScalar(-1.);
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m_rbBFrame.getBasis()[1][1] *= btScalar(-1.);
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m_rbBFrame.getBasis()[1][2] *= btScalar(-1.);
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m_rbBFrame.getBasis()[2][0] *= btScalar(-1.);
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m_rbBFrame.getBasis()[2][1] *= btScalar(-1.);
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m_rbBFrame.getBasis()[2][2] *= btScalar(-1.);
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m_swingSpan1 = btScalar(1e30);
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m_swingSpan2 = btScalar(1e30);
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m_twistSpan = btScalar(1e30);
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m_biasFactor = 0.3f;
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m_relaxationFactor = 1.0f;
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m_solveTwistLimit = false;
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m_solveSwingLimit = false;
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}
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void btConeTwistConstraint::buildJacobian()
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{
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m_appliedImpulse = btScalar(0.);
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//set bias, sign, clear accumulator
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m_swingCorrection = btScalar(0.);
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m_twistLimitSign = btScalar(0.);
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m_solveTwistLimit = false;
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m_solveSwingLimit = false;
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m_accTwistLimitImpulse = btScalar(0.);
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m_accSwingLimitImpulse = btScalar(0.);
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if (!m_angularOnly)
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{
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btVector3 pivotAInW = m_rbA.getCenterOfMassTransform()*m_rbAFrame.getOrigin();
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btVector3 pivotBInW = m_rbB.getCenterOfMassTransform()*m_rbBFrame.getOrigin();
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btVector3 relPos = pivotBInW - pivotAInW;
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btVector3 normal[3];
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if (relPos.length2() > SIMD_EPSILON)
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{
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normal[0] = relPos.normalized();
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}
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else
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{
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normal[0].setValue(btScalar(1.0),0,0);
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}
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btPlaneSpace1(normal[0], normal[1], normal[2]);
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for (int i=0;i<3;i++)
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{
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new (&m_jac[i]) btJacobianEntry(
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m_rbA.getCenterOfMassTransform().getBasis().transpose(),
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m_rbB.getCenterOfMassTransform().getBasis().transpose(),
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pivotAInW - m_rbA.getCenterOfMassPosition(),
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pivotBInW - m_rbB.getCenterOfMassPosition(),
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normal[i],
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m_rbA.getInvInertiaDiagLocal(),
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m_rbA.getInvMass(),
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m_rbB.getInvInertiaDiagLocal(),
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m_rbB.getInvMass());
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}
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}
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btVector3 b1Axis1,b1Axis2,b1Axis3;
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btVector3 b2Axis1,b2Axis2;
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b1Axis1 = getRigidBodyA().getCenterOfMassTransform().getBasis() * this->m_rbAFrame.getBasis().getColumn(0);
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b2Axis1 = getRigidBodyB().getCenterOfMassTransform().getBasis() * this->m_rbBFrame.getBasis().getColumn(0);
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btScalar swing1=btScalar(0.),swing2 = btScalar(0.);
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// Get Frame into world space
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if (m_swingSpan1 >= btScalar(0.05f))
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{
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b1Axis2 = getRigidBodyA().getCenterOfMassTransform().getBasis() * this->m_rbAFrame.getBasis().getColumn(1);
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swing1 = btAtan2Fast( b2Axis1.dot(b1Axis2),b2Axis1.dot(b1Axis1) );
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}
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if (m_swingSpan2 >= btScalar(0.05f))
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{
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b1Axis3 = getRigidBodyA().getCenterOfMassTransform().getBasis() * this->m_rbAFrame.getBasis().getColumn(2);
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swing2 = btAtan2Fast( b2Axis1.dot(b1Axis3),b2Axis1.dot(b1Axis1) );
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}
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btScalar RMaxAngle1Sq = 1.0f / (m_swingSpan1*m_swingSpan1);
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btScalar RMaxAngle2Sq = 1.0f / (m_swingSpan2*m_swingSpan2);
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btScalar EllipseAngle = btFabs(swing1)* RMaxAngle1Sq + btFabs(swing2) * RMaxAngle2Sq;
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if (EllipseAngle > 1.0f)
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{
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m_swingCorrection = EllipseAngle-1.0f;
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m_solveSwingLimit = true;
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// Calculate necessary axis & factors
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m_swingAxis = b2Axis1.cross(b1Axis2* b2Axis1.dot(b1Axis2) + b1Axis3* b2Axis1.dot(b1Axis3));
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m_swingAxis.normalize();
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btScalar swingAxisSign = (b2Axis1.dot(b1Axis1) >= 0.0f) ? 1.0f : -1.0f;
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m_swingAxis *= swingAxisSign;
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m_kSwing = btScalar(1.) / (getRigidBodyA().computeAngularImpulseDenominator(m_swingAxis) +
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getRigidBodyB().computeAngularImpulseDenominator(m_swingAxis));
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}
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// Twist limits
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if (m_twistSpan >= btScalar(0.))
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{
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btVector3 b2Axis2 = getRigidBodyB().getCenterOfMassTransform().getBasis() * this->m_rbBFrame.getBasis().getColumn(1);
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btQuaternion rotationArc = shortestArcQuat(b2Axis1,b1Axis1);
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btVector3 TwistRef = quatRotate(rotationArc,b2Axis2);
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btScalar twist = btAtan2Fast( TwistRef.dot(b1Axis3), TwistRef.dot(b1Axis2) );
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btScalar lockedFreeFactor = (m_twistSpan > btScalar(0.05f)) ? m_limitSoftness : btScalar(0.);
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if (twist <= -m_twistSpan*lockedFreeFactor)
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{
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m_twistCorrection = -(twist + m_twistSpan);
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m_solveTwistLimit = true;
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m_twistAxis = (b2Axis1 + b1Axis1) * 0.5f;
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m_twistAxis.normalize();
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m_twistAxis *= -1.0f;
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m_kTwist = btScalar(1.) / (getRigidBodyA().computeAngularImpulseDenominator(m_twistAxis) +
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getRigidBodyB().computeAngularImpulseDenominator(m_twistAxis));
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} else
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if (twist > m_twistSpan*lockedFreeFactor)
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{
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m_twistCorrection = (twist - m_twistSpan);
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m_solveTwistLimit = true;
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m_twistAxis = (b2Axis1 + b1Axis1) * 0.5f;
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m_twistAxis.normalize();
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m_kTwist = btScalar(1.) / (getRigidBodyA().computeAngularImpulseDenominator(m_twistAxis) +
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getRigidBodyB().computeAngularImpulseDenominator(m_twistAxis));
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}
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}
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}
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void btConeTwistConstraint::solveConstraint(btScalar timeStep)
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{
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btVector3 pivotAInW = m_rbA.getCenterOfMassTransform()*m_rbAFrame.getOrigin();
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btVector3 pivotBInW = m_rbB.getCenterOfMassTransform()*m_rbBFrame.getOrigin();
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btScalar tau = btScalar(0.3);
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btScalar damping = btScalar(1.);
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//linear part
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if (!m_angularOnly)
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{
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btVector3 rel_pos1 = pivotAInW - m_rbA.getCenterOfMassPosition();
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btVector3 rel_pos2 = pivotBInW - m_rbB.getCenterOfMassPosition();
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btVector3 vel1 = m_rbA.getVelocityInLocalPoint(rel_pos1);
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btVector3 vel2 = m_rbB.getVelocityInLocalPoint(rel_pos2);
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btVector3 vel = vel1 - vel2;
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for (int i=0;i<3;i++)
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{
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const btVector3& normal = m_jac[i].m_linearJointAxis;
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btScalar jacDiagABInv = btScalar(1.) / m_jac[i].getDiagonal();
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btScalar rel_vel;
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rel_vel = normal.dot(vel);
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//positional error (zeroth order error)
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btScalar depth = -(pivotAInW - pivotBInW).dot(normal); //this is the error projected on the normal
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btScalar impulse = depth*tau/timeStep * jacDiagABInv - rel_vel * jacDiagABInv;
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m_appliedImpulse += impulse;
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btVector3 impulse_vector = normal * impulse;
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m_rbA.applyImpulse(impulse_vector, pivotAInW - m_rbA.getCenterOfMassPosition());
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m_rbB.applyImpulse(-impulse_vector, pivotBInW - m_rbB.getCenterOfMassPosition());
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}
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}
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{
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///solve angular part
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const btVector3& angVelA = getRigidBodyA().getAngularVelocity();
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const btVector3& angVelB = getRigidBodyB().getAngularVelocity();
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// solve swing limit
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if (m_solveSwingLimit)
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{
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btScalar amplitude = ((angVelB - angVelA).dot( m_swingAxis )*m_relaxationFactor*m_relaxationFactor + m_swingCorrection*(btScalar(1.)/timeStep)*m_biasFactor);
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btScalar impulseMag = amplitude * m_kSwing;
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// Clamp the accumulated impulse
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btScalar temp = m_accSwingLimitImpulse;
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m_accSwingLimitImpulse = btMax(m_accSwingLimitImpulse + impulseMag, 0.0f );
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impulseMag = m_accSwingLimitImpulse - temp;
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btVector3 impulse = m_swingAxis * impulseMag;
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m_rbA.applyTorqueImpulse(impulse);
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m_rbB.applyTorqueImpulse(-impulse);
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}
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// solve twist limit
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if (m_solveTwistLimit)
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{
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btScalar amplitude = ((angVelB - angVelA).dot( m_twistAxis )*m_relaxationFactor*m_relaxationFactor + m_twistCorrection*(btScalar(1.)/timeStep)*m_biasFactor );
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btScalar impulseMag = amplitude * m_kTwist;
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// Clamp the accumulated impulse
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btScalar temp = m_accTwistLimitImpulse;
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m_accTwistLimitImpulse = btMax(m_accTwistLimitImpulse + impulseMag, 0.0f );
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impulseMag = m_accTwistLimitImpulse - temp;
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btVector3 impulse = m_twistAxis * impulseMag;
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m_rbA.applyTorqueImpulse(impulse);
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m_rbB.applyTorqueImpulse(-impulse);
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}
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}
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}
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void btConeTwistConstraint::updateRHS(btScalar timeStep)
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{
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(void)timeStep;
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}
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