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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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46
Demos/GyroscopicDemo/GyroscopicSetup.cpp
View File

@@ -17,43 +17,49 @@ void GyroscopicSetup::initPhysics(GraphicsPhysicsBridge& gfxBridge)
btRigidBody* groundBody;
groundBody = createRigidBody(0, groundTransform, groundShape);
groundBody->setFriction(btSqrt(2));
btVector3 positions[4] = {
btVector3(0.8, -5, 4),
btVector3(0.8, -2, 4),
btVector3(0.8, 2, 4),
btVector3(0.8, 5, 4)
btVector3 positions[5] = {
btVector3( -10, 8,4),
btVector3( -5, 8,4),
btVector3( 0, 8,4),
btVector3( 5, 8,4),
btVector3( 10, 8,4),
};
int gyroflags[4] = {
int gyroflags[5] = {
0,//none, no gyroscopic term
BT_ENABLE_GYROPSCOPIC_FORCE_EXPLICIT,
BT_ENABLE_GYROPSCOPIC_FORCE_IMPLICIT_EWERT,
BT_ENABLE_GYROPSCOPIC_FORCE_IMPLICIT_COOPER,
BT_ENABLE_GYROSCOPIC_FORCE_EXPLICIT,
BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_EWERT,
BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_COOPER,
BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_CATTO,
};
for (int i = 0; i<4; i++)
for (int i = 0; i<5; i++)
{
btCylinderShapeZ* top = new btCylinderShapeZ(btVector3(1, 1, 0.125));
btCapsuleShapeZ* pin = new btCapsuleShapeZ(0.05, 1.5);
top->setMargin(0.01);
btCylinderShapeZ* pin = new btCylinderShapeZ(btVector3(0.1,0.1, 0.2));
btBoxShape* box = new btBoxShape(btVector3(1,0.1,0.1));
box->setMargin(0.01);
pin->setMargin(0.01);
btCompoundShape* compound = new btCompoundShape();
compound->addChildShape(btTransform::getIdentity(), top);
compound->addChildShape(btTransform::getIdentity(), pin);
btTransform offsetBox(btMatrix3x3::getIdentity(),btVector3(0,0,0.2));
compound->addChildShape(offsetBox, box);
btScalar masses[2] = {0.3,0.1};
btVector3 localInertia;
top->calculateLocalInertia(1, localInertia);
btTransform principal;
compound->calculatePrincipalAxisTransform(masses,principal,localInertia);
btRigidBody* body = new btRigidBody(1, 0, compound, localInertia);
btTransform tr;
tr.setIdentity();
tr.setOrigin(positions[i]);
body->setCenterOfMassTransform(tr);
body->setAngularVelocity(btVector3(1, 17, 3));
body->setLinearVelocity(btVector3(0, 0, 0));
body->setAngularVelocity(btVector3(0, 0.1, 10));//51));
//body->setLinearVelocity(btVector3(3, 0, 0));
body->setFriction(btSqrt(1));
m_dynamicsWorld->addRigidBody(body);
body->setFlags(gyroflags[i]);
body->setDamping(0.00001f, 0.0001f);
m_dynamicsWorld->getSolverInfo().m_maxGyroscopicForce = 10.f;
body->setDamping(0.0000f, 0.000f);
}

12
src/BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.cpp
View File

@@ -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
View File

@@ -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;