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added Erin Catto's 'local' implicit coriolis/gyroscopic force, next to 'Ewert', Cooper, explicit and none

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Configured the gyroscopic demo to show the Dzhanibekov effect
see also https://www.youtube.com/watch?v=L2o9eBl_Gzw
This commit is contained in:
Erwin Coumans
2015-03-24 23:16:45 -07:00
parent 1e13454511
commit 0a04a745dd
4 changed files with 83 additions and 27 deletions
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12
src/BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.cpp
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@@ -1269,21 +1269,27 @@ btScalar btSequentialImpulseConstraintSolver::solveGroupCacheFriendlySetup(btCol
{
btSolverBody& solverBody = m_tmpSolverBodyPool[bodyId];
btVector3 gyroForce (0,0,0);
if (body->getFlags()&BT_ENABLE_GYROPSCOPIC_FORCE_EXPLICIT)
if (body->getFlags()&BT_ENABLE_GYROSCOPIC_FORCE_EXPLICIT)
{
gyroForce = body->computeGyroscopicForce(infoGlobal.m_maxGyroscopicForce);
solverBody.m_externalTorqueImpulse -= gyroForce*body->getInvInertiaTensorWorld()*infoGlobal.m_timeStep;
}
if (body->getFlags()&BT_ENABLE_GYROPSCOPIC_FORCE_IMPLICIT_EWERT)
if (body->getFlags()&BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_EWERT)
{
gyroForce = body->computeGyroscopicImpulseImplicit_Ewert(infoGlobal.m_timeStep);
solverBody.m_externalTorqueImpulse += gyroForce;
}
if (body->getFlags()&BT_ENABLE_GYROPSCOPIC_FORCE_IMPLICIT_COOPER)
if (body->getFlags()&BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_COOPER)
{
gyroForce = body->computeGyroscopicImpulseImplicit_Cooper(infoGlobal.m_timeStep);
solverBody.m_externalTorqueImpulse += gyroForce;
}
if (body->getFlags()&BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_CATTO)
{
gyroForce = body->computeGyroscopicImpulseImplicit_Catto(infoGlobal.m_timeStep);
solverBody.m_externalTorqueImpulse += gyroForce;
}
}

43
src/BulletDynamics/Dynamics/btRigidBody.cpp
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@@ -87,7 +87,7 @@ void btRigidBody::setupRigidBody(const btRigidBody::btRigidBodyConstructionInfo&
setMassProps(constructionInfo.m_mass, constructionInfo.m_localInertia);
updateInertiaTensor();
m_rigidbodyFlags = BT_ENABLE_GYROPSCOPIC_FORCE_IMPLICIT_EWERT;
m_rigidbodyFlags = BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_EWERT;
m_deltaLinearVelocity.setZero();
@@ -311,6 +311,46 @@ void btSetCrossMatrixMinus(btMatrix3x3& res, const btVector3& a)
+a_1, -a_0, 0);
}
btVector3 btRigidBody::computeGyroscopicImpulseImplicit_Catto(btScalar step) const
{
btVector3 idl = getLocalInertia();
btVector3 omega1 = getAngularVelocity();
btQuaternion q = getWorldTransform().getRotation();
// Convert to body coordinates
btVector3 omegab = quatRotate(q.inverse(), omega1);
btMatrix3x3 Ib;
Ib.setValue(idl.x(),0,0,
0,idl.y(),0,
0,0,idl.z());
btVector3 ibo = Ib*omegab;
// Residual vector
btVector3 f = step * omegab.cross(ibo);
btMatrix3x3 skew0;
omegab.getSkewSymmetricMatrix(&skew0[0], &skew0[1], &skew0[2]);
btVector3 om = Ib*omegab;
btMatrix3x3 skew1;
om.getSkewSymmetricMatrix(&skew1[0],&skew1[1],&skew1[2]);
// Jacobian
btMatrix3x3 J = Ib + (skew0*Ib - skew1)*step;
btMatrix3x3 Jinv = J.inverse();
btVector3 omega_div = Jinv*f;
// Single Newton-Raphson update
omegab = omegab - omega_div;//Solve33(J, f);
// Back to world coordinates
btVector3 omega2 = quatRotate(q,omegab);
btVector3 gf = omega2-omega1;
return gf;
}
btVector3 btRigidBody::computeGyroscopicImpulseImplicit_Cooper(btScalar step) const
{
#if 0
@@ -394,6 +434,7 @@ if (dInvertMatrix3(itInv, Itild) != 0) {
}
#endif
btVector3 tau0 = Itild * L;
printf("tau0 = %f,%f,%f\n",tau0.x(),tau0.y(),tau0.z());
return tau0;
return btVector3(0, 0, 0);
}

9
src/BulletDynamics/Dynamics/btRigidBody.h
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@@ -43,9 +43,10 @@ enum btRigidBodyFlags
BT_DISABLE_WORLD_GRAVITY = 1,
///BT_ENABLE_GYROPSCOPIC_FORCE flags is enabled by default in Bullet 2.83 and onwards.
///See Demos/GyroscopicDemo and computeGyroscopicImpulseImplicit
BT_ENABLE_GYROPSCOPIC_FORCE_EXPLICIT = 2,
BT_ENABLE_GYROPSCOPIC_FORCE_IMPLICIT_COOPER=4,
BT_ENABLE_GYROPSCOPIC_FORCE_IMPLICIT_EWERT=8
BT_ENABLE_GYROSCOPIC_FORCE_EXPLICIT = 2,
BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_COOPER=4,
BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_EWERT=8,
BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_CATTO=16,
};
@@ -535,6 +536,8 @@ public:
btVector3 computeGyroscopicImpulseImplicit_Ewert(btScalar dt) const;
btVector3 computeGyroscopicImpulseImplicit_Cooper(btScalar step) const;
btVector3 computeGyroscopicImpulseImplicit_Catto(btScalar step) const;
btVector3 computeGyroscopicForce(btScalar maxGyroscopicForce) const;//explicit version is best avoided, it gains energy
btVector3 getLocalInertia() const;