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278 lines
9.5 KiB
C++
278 lines
9.5 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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btHingeConstraint::btHingeConstraint()
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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(rbA,rbB),m_pivotInA(pivotInA),m_pivotInB(pivotInB),
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m_axisInA(axisInA),
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m_axisInB(-axisInB),
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m_angularOnly(false)
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{
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}
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btHingeConstraint::btHingeConstraint(btRigidBody& rbA,const btVector3& pivotInA,btVector3& axisInA)
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:btTypedConstraint(rbA),m_pivotInA(pivotInA),m_pivotInB(rbA.getCenterOfMassTransform()(pivotInA)),
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m_axisInA(axisInA),
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//fixed axis in worldspace
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m_axisInB(rbA.getCenterOfMassTransform().getBasis() * -axisInA),
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m_angularOnly(false)
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{
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}
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void btHingeConstraint::buildJacobian()
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{
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m_appliedImpulse = 0.f;
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btVector3 normal(0,0,0);
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if (!m_angularOnly)
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{
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for (int i=0;i<3;i++)
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{
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normal[i] = 1;
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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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m_rbA.getCenterOfMassTransform()*m_pivotInA - m_rbA.getCenterOfMassPosition(),
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m_rbB.getCenterOfMassTransform()*m_pivotInB - m_rbB.getCenterOfMassPosition(),
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normal,
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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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normal[i] = 0;
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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 axisWorldA = getRigidBodyA().getCenterOfMassTransform().getBasis() * m_axisInA;
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btVector3 jointAxis0;
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btVector3 jointAxis1;
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btPlaneSpace1(axisWorldA,jointAxis0,jointAxis1);
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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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}
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void btHingeConstraint::solveConstraint(btScalar timeStep)
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{
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//#define NEW_IMPLEMENTATION
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#ifdef NEW_IMPLEMENTATION
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btScalar tau = 0.3f;
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btScalar damping = 1.f;
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btVector3 pivotAInW = m_rbA.getCenterOfMassTransform()*m_pivotInA;
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btVector3 pivotBInW = m_rbB.getCenterOfMassTransform()*m_pivotInB;
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// Dirk: Don't we need to update this after each applied impulse
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btVector3 angvelA; // = m_rbA.getCenterOfMassTransform().getBasis().transpose() * m_rbA.getAngularVelocity();
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btVector3 angvelB; // = m_rbB.getCenterOfMassTransform().getBasis().transpose() * m_rbB.getAngularVelocity();
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if (!m_angularOnly)
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{
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btVector3 normal(0,0,0);
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for (int i=0;i<3;i++)
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{
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normal[i] = 1;
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btScalar jacDiagABInv = 1.f / m_jac[i].getDiagonal();
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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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// Dirk: Get new angular velocity since it changed after applying an impulse
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angvelA = m_rbA.getCenterOfMassTransform().getBasis().transpose() * m_rbA.getAngularVelocity();
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angvelB = m_rbB.getCenterOfMassTransform().getBasis().transpose() * m_rbB.getAngularVelocity();
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//velocity error (first order error)
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btScalar rel_vel = m_jac[i].getRelativeVelocity(m_rbA.getLinearVelocity(),angvelA,
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m_rbB.getLinearVelocity(),angvelB);
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//positional error (zeroth order error)
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btScalar depth = -(pivotAInW - pivotBInW).dot(normal);
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btScalar impulse = tau*depth/timeStep * jacDiagABInv - damping * rel_vel * jacDiagABInv;
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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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normal[i] = 0;
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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_axisInA;
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btVector3 axisB = getRigidBodyB().getCenterOfMassTransform().getBasis() * m_axisInB;
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// constraint axes in world space
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btVector3 jointAxis0;
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btVector3 jointAxis1;
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btPlaneSpace1(axisA,jointAxis0,jointAxis1);
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// Dirk: Get new angular velocity since it changed after applying an impulse
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angvelA = m_rbA.getCenterOfMassTransform().getBasis().transpose() * m_rbA.getAngularVelocity();
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angvelB = m_rbB.getCenterOfMassTransform().getBasis().transpose() * m_rbB.getAngularVelocity();
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btScalar jacDiagABInv0 = 1.f / m_jacAng[0].getDiagonal();
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btScalar rel_vel0 = m_jacAng[0].getRelativeVelocity(m_rbA.getLinearVelocity(),angvelA,
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m_rbB.getLinearVelocity(),angvelB);
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float tau1 = tau;//0.f;
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btScalar impulse0 = (tau1 * axisB.dot(jointAxis1) / timeStep - damping * rel_vel0) * jacDiagABInv0;
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btVector3 angular_impulse0 = jointAxis0 * impulse0;
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m_rbA.applyTorqueImpulse( angular_impulse0);
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m_rbB.applyTorqueImpulse(-angular_impulse0);
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// Dirk: Get new angular velocity since it changed after applying an impulse
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angvelA = m_rbA.getCenterOfMassTransform().getBasis().transpose() * m_rbA.getAngularVelocity();
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angvelB = m_rbB.getCenterOfMassTransform().getBasis().transpose() * m_rbB.getAngularVelocity();
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btScalar jacDiagABInv1 = 1.f / m_jacAng[1].getDiagonal();
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btScalar rel_vel1 = m_jacAng[1].getRelativeVelocity(m_rbA.getLinearVelocity(),angvelA,
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m_rbB.getLinearVelocity(),angvelB);;
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btScalar impulse1 = -(tau1 * axisB.dot(jointAxis0) / timeStep + damping * rel_vel1) * jacDiagABInv1;
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btVector3 angular_impulse1 = jointAxis1 * impulse1;
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m_rbA.applyTorqueImpulse( angular_impulse1);
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m_rbB.applyTorqueImpulse(-angular_impulse1);
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#else
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btVector3 pivotAInW = m_rbA.getCenterOfMassTransform()*m_pivotInA;
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btVector3 pivotBInW = m_rbB.getCenterOfMassTransform()*m_pivotInB;
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btVector3 normal(0,0,0);
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btScalar tau = 0.3f;
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btScalar damping = 1.f;
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//linear part
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{
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for (int i=0;i<3;i++)
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{
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normal[i] = 1;
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btScalar jacDiagABInv = 1.f / m_jac[i].getDiagonal();
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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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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 - damping * rel_vel * jacDiagABInv * damping;
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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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normal[i] = 0;
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}
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}
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if (!m_angularOnly)
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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_axisInA;
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btVector3 axisB = getRigidBodyB().getCenterOfMassTransform().getBasis() * m_axisInB;
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const btVector3& angVelA = getRigidBodyA().getAngularVelocity();
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const btVector3& angVelB = getRigidBodyB().getAngularVelocity();
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btVector3 angA = angVelA - axisA * axisA.dot(angVelA);
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btVector3 angB = angVelB - axisB * axisB.dot(angVelB);
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btVector3 velrel = angA-angB;
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//solve angular velocity correction
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float relaxation = 1.f;
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float len = velrel.length();
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if (len > 0.00001f)
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{
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btVector3 normal = velrel.normalized();
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float denom = getRigidBodyA().computeAngularImpulseDenominator(normal) +
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getRigidBodyB().computeAngularImpulseDenominator(normal);
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// scale for mass and relaxation
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velrel *= (1.f/denom) * 0.9;
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}
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//solve angular positional correction
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btVector3 angularError = -axisA.cross(axisB) *(1.f/timeStep);
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float len2 = angularError.length();
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if (len2>0.00001f)
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{
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btVector3 normal2 = angularError.normalized();
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float denom2 = getRigidBodyA().computeAngularImpulseDenominator(normal2) +
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getRigidBodyB().computeAngularImpulseDenominator(normal2);
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angularError *= (1.f/denom2) * relaxation;
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}
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m_rbA.applyTorqueImpulse(-velrel+angularError);
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m_rbB.applyTorqueImpulse(velrel-angularError);
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}
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#endif
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}
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void btHingeConstraint::updateRHS(btScalar timeStep)
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{
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}
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