399 lines
14 KiB
C++
399 lines
14 KiB
C++
/*
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Bullet Continuous Collision Detection and Physics Library
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Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/
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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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#include "btHingeConstraint.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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btHingeConstraint::btHingeConstraint()
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: btTypedConstraint (HINGE_CONSTRAINT_TYPE),
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m_enableAngularMotor(false)
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{
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}
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btHingeConstraint::btHingeConstraint(btRigidBody& rbA,btRigidBody& rbB, const btVector3& pivotInA,const btVector3& pivotInB,
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btVector3& axisInA,btVector3& axisInB)
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:btTypedConstraint(HINGE_CONSTRAINT_TYPE, rbA,rbB),
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m_angularOnly(false),
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m_enableAngularMotor(false)
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{
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m_rbAFrame.getOrigin() = pivotInA;
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// since no frame is given, assume this to be zero angle and just pick rb transform axis
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btVector3 rbAxisA1 = rbA.getCenterOfMassTransform().getBasis().getColumn(0);
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btScalar projection = rbAxisA1.dot(axisInA);
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if (projection > SIMD_EPSILON)
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rbAxisA1 = rbAxisA1*projection - axisInA;
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else
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rbAxisA1 = rbA.getCenterOfMassTransform().getBasis().getColumn(1);
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btVector3 rbAxisA2 = rbAxisA1.cross(axisInA);
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m_rbAFrame.getBasis().setValue( rbAxisA1.getX(),rbAxisA2.getX(),axisInA.getX(),
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rbAxisA1.getY(),rbAxisA2.getY(),axisInA.getY(),
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rbAxisA1.getZ(),rbAxisA2.getZ(),axisInA.getZ() );
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btQuaternion rotationArc = shortestArcQuat(axisInA,axisInB);
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btVector3 rbAxisB1 = quatRotate(rotationArc,rbAxisA1);
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btVector3 rbAxisB2 = rbAxisB1.cross(axisInB);
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m_rbBFrame.getOrigin() = pivotInB;
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m_rbBFrame.getBasis().setValue( rbAxisB1.getX(),rbAxisB2.getX(),-axisInB.getX(),
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rbAxisB1.getY(),rbAxisB2.getY(),-axisInB.getY(),
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rbAxisB1.getZ(),rbAxisB2.getZ(),-axisInB.getZ() );
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//start with free
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m_lowerLimit = btScalar(1e30);
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m_upperLimit = btScalar(-1e30);
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m_biasFactor = 0.3f;
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m_relaxationFactor = 1.0f;
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m_limitSoftness = 0.9f;
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m_solveLimit = false;
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}
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btHingeConstraint::btHingeConstraint(btRigidBody& rbA,const btVector3& pivotInA,btVector3& axisInA)
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:btTypedConstraint(HINGE_CONSTRAINT_TYPE, rbA), m_angularOnly(false), m_enableAngularMotor(false)
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{
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// since no frame is given, assume this to be zero angle and just pick rb transform axis
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// fixed axis in worldspace
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btVector3 rbAxisA1 = rbA.getCenterOfMassTransform().getBasis().getColumn(0);
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btScalar projection = rbAxisA1.dot(axisInA);
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if (projection > SIMD_EPSILON)
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rbAxisA1 = rbAxisA1*projection - axisInA;
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else
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rbAxisA1 = rbA.getCenterOfMassTransform().getBasis().getColumn(1);
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btVector3 rbAxisA2 = axisInA.cross(rbAxisA1);
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m_rbAFrame.getOrigin() = pivotInA;
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m_rbAFrame.getBasis().setValue( rbAxisA1.getX(),rbAxisA2.getX(),axisInA.getX(),
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rbAxisA1.getY(),rbAxisA2.getY(),axisInA.getY(),
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rbAxisA1.getZ(),rbAxisA2.getZ(),axisInA.getZ() );
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btVector3 axisInB = rbA.getCenterOfMassTransform().getBasis() * -axisInA;
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btQuaternion rotationArc = shortestArcQuat(axisInA,axisInB);
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btVector3 rbAxisB1 = quatRotate(rotationArc,rbAxisA1);
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btVector3 rbAxisB2 = axisInB.cross(rbAxisB1);
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m_rbBFrame.getOrigin() = rbA.getCenterOfMassTransform()(pivotInA);
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m_rbBFrame.getBasis().setValue( rbAxisB1.getX(),rbAxisB2.getX(),axisInB.getX(),
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rbAxisB1.getY(),rbAxisB2.getY(),axisInB.getY(),
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rbAxisB1.getZ(),rbAxisB2.getZ(),axisInB.getZ() );
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//start with free
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m_lowerLimit = btScalar(1e30);
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m_upperLimit = btScalar(-1e30);
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m_biasFactor = 0.3f;
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m_relaxationFactor = 1.0f;
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m_limitSoftness = 0.9f;
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m_solveLimit = false;
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}
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btHingeConstraint::btHingeConstraint(btRigidBody& rbA,btRigidBody& rbB,
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const btTransform& rbAFrame, const btTransform& rbBFrame)
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:btTypedConstraint(HINGE_CONSTRAINT_TYPE, rbA,rbB),m_rbAFrame(rbAFrame),m_rbBFrame(rbBFrame),
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m_angularOnly(false),
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m_enableAngularMotor(false)
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{
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// flip axis
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m_rbBFrame.getBasis()[0][2] *= btScalar(-1.);
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m_rbBFrame.getBasis()[1][2] *= btScalar(-1.);
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m_rbBFrame.getBasis()[2][2] *= btScalar(-1.);
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//start with free
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m_lowerLimit = btScalar(1e30);
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m_upperLimit = btScalar(-1e30);
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m_biasFactor = 0.3f;
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m_relaxationFactor = 1.0f;
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m_limitSoftness = 0.9f;
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m_solveLimit = false;
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}
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btHingeConstraint::btHingeConstraint(btRigidBody& rbA, const btTransform& rbAFrame)
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:btTypedConstraint(HINGE_CONSTRAINT_TYPE, rbA),m_rbAFrame(rbAFrame),m_rbBFrame(rbAFrame),
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m_angularOnly(false),
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m_enableAngularMotor(false)
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{
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// flip axis
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m_rbBFrame.getBasis()[0][2] *= btScalar(-1.);
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m_rbBFrame.getBasis()[1][2] *= btScalar(-1.);
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m_rbBFrame.getBasis()[2][2] *= btScalar(-1.);
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//start with free
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m_lowerLimit = btScalar(1e30);
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m_upperLimit = btScalar(-1e30);
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m_biasFactor = 0.3f;
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m_relaxationFactor = 1.0f;
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m_limitSoftness = 0.9f;
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m_solveLimit = false;
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}
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void btHingeConstraint::buildJacobian()
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{
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m_appliedImpulse = 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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//calculate two perpendicular jointAxis, orthogonal to hingeAxis
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//these two jointAxis require equal angular velocities for both bodies
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//this is unused for now, it's a todo
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btVector3 jointAxis0local;
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btVector3 jointAxis1local;
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btPlaneSpace1(m_rbAFrame.getBasis().getColumn(2),jointAxis0local,jointAxis1local);
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getRigidBodyA().getCenterOfMassTransform().getBasis() * m_rbAFrame.getBasis().getColumn(2);
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btVector3 jointAxis0 = getRigidBodyA().getCenterOfMassTransform().getBasis() * jointAxis0local;
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btVector3 jointAxis1 = getRigidBodyA().getCenterOfMassTransform().getBasis() * jointAxis1local;
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btVector3 hingeAxisWorld = getRigidBodyA().getCenterOfMassTransform().getBasis() * m_rbAFrame.getBasis().getColumn(2);
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new (&m_jacAng[0]) btJacobianEntry(jointAxis0,
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m_rbA.getCenterOfMassTransform().getBasis().transpose(),
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m_rbB.getCenterOfMassTransform().getBasis().transpose(),
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m_rbA.getInvInertiaDiagLocal(),
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m_rbB.getInvInertiaDiagLocal());
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new (&m_jacAng[1]) btJacobianEntry(jointAxis1,
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m_rbA.getCenterOfMassTransform().getBasis().transpose(),
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m_rbB.getCenterOfMassTransform().getBasis().transpose(),
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m_rbA.getInvInertiaDiagLocal(),
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m_rbB.getInvInertiaDiagLocal());
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new (&m_jacAng[2]) btJacobianEntry(hingeAxisWorld,
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m_rbA.getCenterOfMassTransform().getBasis().transpose(),
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m_rbB.getCenterOfMassTransform().getBasis().transpose(),
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m_rbA.getInvInertiaDiagLocal(),
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m_rbB.getInvInertiaDiagLocal());
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// Compute limit information
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btScalar hingeAngle = getHingeAngle();
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//set bias, sign, clear accumulator
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m_correction = btScalar(0.);
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m_limitSign = btScalar(0.);
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m_solveLimit = false;
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m_accLimitImpulse = btScalar(0.);
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if (m_lowerLimit < m_upperLimit)
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{
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if (hingeAngle <= m_lowerLimit*m_limitSoftness)
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{
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m_correction = (m_lowerLimit - hingeAngle);
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m_limitSign = 1.0f;
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m_solveLimit = true;
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}
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else if (hingeAngle >= m_upperLimit*m_limitSoftness)
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{
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m_correction = m_upperLimit - hingeAngle;
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m_limitSign = -1.0f;
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m_solveLimit = true;
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}
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}
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//Compute K = J*W*J' for hinge axis
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btVector3 axisA = getRigidBodyA().getCenterOfMassTransform().getBasis() * m_rbAFrame.getBasis().getColumn(2);
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m_kHinge = 1.0f / (getRigidBodyA().computeAngularImpulseDenominator(axisA) +
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getRigidBodyB().computeAngularImpulseDenominator(axisA));
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}
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void btHingeConstraint::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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// get axes in world space
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btVector3 axisA = getRigidBodyA().getCenterOfMassTransform().getBasis() * m_rbAFrame.getBasis().getColumn(2);
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btVector3 axisB = getRigidBodyB().getCenterOfMassTransform().getBasis() * m_rbBFrame.getBasis().getColumn(2);
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const btVector3& angVelA = getRigidBodyA().getAngularVelocity();
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const btVector3& angVelB = getRigidBodyB().getAngularVelocity();
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btVector3 angVelAroundHingeAxisA = axisA * axisA.dot(angVelA);
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btVector3 angVelAroundHingeAxisB = axisB * axisB.dot(angVelB);
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btVector3 angAorthog = angVelA - angVelAroundHingeAxisA;
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btVector3 angBorthog = angVelB - angVelAroundHingeAxisB;
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btVector3 velrelOrthog = angAorthog-angBorthog;
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{
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//solve orthogonal angular velocity correction
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btScalar relaxation = btScalar(1.);
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btScalar len = velrelOrthog.length();
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if (len > btScalar(0.00001))
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{
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btVector3 normal = velrelOrthog.normalized();
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btScalar denom = getRigidBodyA().computeAngularImpulseDenominator(normal) +
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getRigidBodyB().computeAngularImpulseDenominator(normal);
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// scale for mass and relaxation
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//todo: expose this 0.9 factor to developer
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velrelOrthog *= (btScalar(1.)/denom) * m_relaxationFactor;
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}
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//solve angular positional correction
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btVector3 angularError = -axisA.cross(axisB) *(btScalar(1.)/timeStep);
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btScalar len2 = angularError.length();
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if (len2>btScalar(0.00001))
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{
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btVector3 normal2 = angularError.normalized();
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btScalar denom2 = getRigidBodyA().computeAngularImpulseDenominator(normal2) +
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getRigidBodyB().computeAngularImpulseDenominator(normal2);
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angularError *= (btScalar(1.)/denom2) * relaxation;
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}
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m_rbA.applyTorqueImpulse(-velrelOrthog+angularError);
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m_rbB.applyTorqueImpulse(velrelOrthog-angularError);
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// solve limit
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if (m_solveLimit)
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{
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btScalar amplitude = ( (angVelB - angVelA).dot( axisA )*m_relaxationFactor + m_correction* (btScalar(1.)/timeStep)*m_biasFactor ) * m_limitSign;
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btScalar impulseMag = amplitude * m_kHinge;
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// Clamp the accumulated impulse
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btScalar temp = m_accLimitImpulse;
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m_accLimitImpulse = btMax(m_accLimitImpulse + impulseMag, btScalar(0) );
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impulseMag = m_accLimitImpulse - temp;
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btVector3 impulse = axisA * impulseMag * m_limitSign;
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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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//apply motor
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if (m_enableAngularMotor)
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{
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//todo: add limits too
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btVector3 angularLimit(0,0,0);
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btVector3 velrel = angVelAroundHingeAxisA - angVelAroundHingeAxisB;
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btScalar projRelVel = velrel.dot(axisA);
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btScalar desiredMotorVel = m_motorTargetVelocity;
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btScalar motor_relvel = desiredMotorVel - projRelVel;
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btScalar unclippedMotorImpulse = m_kHinge * motor_relvel;;
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//todo: should clip against accumulated impulse
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btScalar clippedMotorImpulse = unclippedMotorImpulse > m_maxMotorImpulse ? m_maxMotorImpulse : unclippedMotorImpulse;
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clippedMotorImpulse = clippedMotorImpulse < -m_maxMotorImpulse ? -m_maxMotorImpulse : clippedMotorImpulse;
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btVector3 motorImp = clippedMotorImpulse * axisA;
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m_rbA.applyTorqueImpulse(motorImp+angularLimit);
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m_rbB.applyTorqueImpulse(-motorImp-angularLimit);
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}
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}
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}
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void btHingeConstraint::updateRHS(btScalar timeStep)
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{
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(void)timeStep;
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}
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btScalar btHingeConstraint::getHingeAngle()
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{
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const btVector3 refAxis0 = getRigidBodyA().getCenterOfMassTransform().getBasis() * m_rbAFrame.getBasis().getColumn(0);
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const btVector3 refAxis1 = getRigidBodyA().getCenterOfMassTransform().getBasis() * m_rbAFrame.getBasis().getColumn(1);
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const btVector3 swingAxis = getRigidBodyB().getCenterOfMassTransform().getBasis() * m_rbBFrame.getBasis().getColumn(1);
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return btAtan2Fast( swingAxis.dot(refAxis0), swingAxis.dot(refAxis1) );
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}
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