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-rw-r--r--thirdparty/bullet/BulletSoftBody/btDeformableContactConstraint.cpp979
1 files changed, 562 insertions, 417 deletions
diff --git a/thirdparty/bullet/BulletSoftBody/btDeformableContactConstraint.cpp b/thirdparty/bullet/BulletSoftBody/btDeformableContactConstraint.cpp
index 2864446de6..09398d79a5 100644
--- a/thirdparty/bullet/BulletSoftBody/btDeformableContactConstraint.cpp
+++ b/thirdparty/bullet/BulletSoftBody/btDeformableContactConstraint.cpp
@@ -16,387 +16,503 @@
#include "btDeformableContactConstraint.h"
/* ================ Deformable Node Anchor =================== */
btDeformableNodeAnchorConstraint::btDeformableNodeAnchorConstraint(const btSoftBody::DeformableNodeRigidAnchor& a, const btContactSolverInfo& infoGlobal)
-: m_anchor(&a)
-, btDeformableContactConstraint(a.m_cti.m_normal, infoGlobal)
+ : m_anchor(&a), btDeformableContactConstraint(a.m_cti.m_normal, infoGlobal)
{
}
btDeformableNodeAnchorConstraint::btDeformableNodeAnchorConstraint(const btDeformableNodeAnchorConstraint& other)
-: m_anchor(other.m_anchor)
-, btDeformableContactConstraint(other)
+ : m_anchor(other.m_anchor), btDeformableContactConstraint(other)
{
}
btVector3 btDeformableNodeAnchorConstraint::getVa() const
{
- const btSoftBody::sCti& cti = m_anchor->m_cti;
- btVector3 va(0, 0, 0);
- if (cti.m_colObj->hasContactResponse())
- {
- btRigidBody* rigidCol = 0;
- btMultiBodyLinkCollider* multibodyLinkCol = 0;
-
- // grab the velocity of the rigid body
- if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
- {
- rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
- va = rigidCol ? (rigidCol->getVelocityInLocalPoint(m_anchor->m_c1)) : btVector3(0, 0, 0);
- }
- else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
- {
- multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
- if (multibodyLinkCol)
- {
- const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
- const btScalar* J_n = &m_anchor->jacobianData_normal.m_jacobians[0];
- const btScalar* J_t1 = &m_anchor->jacobianData_t1.m_jacobians[0];
- const btScalar* J_t2 = &m_anchor->jacobianData_t2.m_jacobians[0];
- const btScalar* local_v = multibodyLinkCol->m_multiBody->getVelocityVector();
- const btScalar* local_dv = multibodyLinkCol->m_multiBody->getDeltaVelocityVector();
- // add in the normal component of the va
- btScalar vel = 0.0;
- for (int k = 0; k < ndof; ++k)
- {
- vel += (local_v[k]+local_dv[k]) * J_n[k];
- }
- va = cti.m_normal * vel;
- // add in the tangential components of the va
- vel = 0.0;
- for (int k = 0; k < ndof; ++k)
- {
- vel += (local_v[k]+local_dv[k]) * J_t1[k];
- }
- va += m_anchor->t1 * vel;
- vel = 0.0;
- for (int k = 0; k < ndof; ++k)
- {
- vel += (local_v[k]+local_dv[k]) * J_t2[k];
- }
- va += m_anchor->t2 * vel;
- }
- }
- }
- return va;
+ const btSoftBody::sCti& cti = m_anchor->m_cti;
+ btVector3 va(0, 0, 0);
+ if (cti.m_colObj->hasContactResponse())
+ {
+ btRigidBody* rigidCol = 0;
+ btMultiBodyLinkCollider* multibodyLinkCol = 0;
+
+ // grab the velocity of the rigid body
+ if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
+ {
+ rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
+ va = rigidCol ? (rigidCol->getVelocityInLocalPoint(m_anchor->m_c1)) : btVector3(0, 0, 0);
+ }
+ else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
+ {
+ multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
+ if (multibodyLinkCol)
+ {
+ const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
+ const btScalar* J_n = &m_anchor->jacobianData_normal.m_jacobians[0];
+ const btScalar* J_t1 = &m_anchor->jacobianData_t1.m_jacobians[0];
+ const btScalar* J_t2 = &m_anchor->jacobianData_t2.m_jacobians[0];
+ const btScalar* local_v = multibodyLinkCol->m_multiBody->getVelocityVector();
+ const btScalar* local_dv = multibodyLinkCol->m_multiBody->getDeltaVelocityVector();
+ // add in the normal component of the va
+ btScalar vel = 0.0;
+ for (int k = 0; k < ndof; ++k)
+ {
+ vel += (local_v[k] + local_dv[k]) * J_n[k];
+ }
+ va = cti.m_normal * vel;
+ // add in the tangential components of the va
+ vel = 0.0;
+ for (int k = 0; k < ndof; ++k)
+ {
+ vel += (local_v[k] + local_dv[k]) * J_t1[k];
+ }
+ va += m_anchor->t1 * vel;
+ vel = 0.0;
+ for (int k = 0; k < ndof; ++k)
+ {
+ vel += (local_v[k] + local_dv[k]) * J_t2[k];
+ }
+ va += m_anchor->t2 * vel;
+ }
+ }
+ }
+ return va;
}
btScalar btDeformableNodeAnchorConstraint::solveConstraint(const btContactSolverInfo& infoGlobal)
{
- const btSoftBody::sCti& cti = m_anchor->m_cti;
- btVector3 va = getVa();
- btVector3 vb = getVb();
- btVector3 vr = (vb - va);
- // + (m_anchor->m_node->m_x - cti.m_colObj->getWorldTransform() * m_anchor->m_local) * 10.0
- const btScalar dn = btDot(vr, vr);
- // dn is the normal component of velocity diffrerence. Approximates the residual. // todo xuchenhan@: this prob needs to be scaled by dt
- btScalar residualSquare = dn*dn;
- btVector3 impulse = m_anchor->m_c0 * vr;
- // apply impulse to deformable nodes involved and change their velocities
- applyImpulse(impulse);
-
- // apply impulse to the rigid/multibodies involved and change their velocities
- if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
- {
- btRigidBody* rigidCol = 0;
- rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
- if (rigidCol)
- {
- rigidCol->applyImpulse(impulse, m_anchor->m_c1);
- }
- }
- else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
- {
- btMultiBodyLinkCollider* multibodyLinkCol = 0;
- multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
- if (multibodyLinkCol)
- {
- const btScalar* deltaV_normal = &m_anchor->jacobianData_normal.m_deltaVelocitiesUnitImpulse[0];
- // apply normal component of the impulse
- multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof2(deltaV_normal, impulse.dot(cti.m_normal));
- // apply tangential component of the impulse
- const btScalar* deltaV_t1 = &m_anchor->jacobianData_t1.m_deltaVelocitiesUnitImpulse[0];
- multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof2(deltaV_t1, impulse.dot(m_anchor->t1));
- const btScalar* deltaV_t2 = &m_anchor->jacobianData_t2.m_deltaVelocitiesUnitImpulse[0];
- multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof2(deltaV_t2, impulse.dot(m_anchor->t2));
- }
- }
- return residualSquare;
+ const btSoftBody::sCti& cti = m_anchor->m_cti;
+ btVector3 va = getVa();
+ btVector3 vb = getVb();
+ btVector3 vr = (vb - va);
+ // + (m_anchor->m_node->m_x - cti.m_colObj->getWorldTransform() * m_anchor->m_local) * 10.0
+ const btScalar dn = btDot(vr, vr);
+ // dn is the normal component of velocity diffrerence. Approximates the residual. // todo xuchenhan@: this prob needs to be scaled by dt
+ btScalar residualSquare = dn * dn;
+ btVector3 impulse = m_anchor->m_c0 * vr;
+ // apply impulse to deformable nodes involved and change their velocities
+ applyImpulse(impulse);
+
+ // apply impulse to the rigid/multibodies involved and change their velocities
+ if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
+ {
+ btRigidBody* rigidCol = 0;
+ rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
+ if (rigidCol)
+ {
+ rigidCol->applyImpulse(impulse, m_anchor->m_c1);
+ }
+ }
+ else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
+ {
+ btMultiBodyLinkCollider* multibodyLinkCol = 0;
+ multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
+ if (multibodyLinkCol)
+ {
+ const btScalar* deltaV_normal = &m_anchor->jacobianData_normal.m_deltaVelocitiesUnitImpulse[0];
+ // apply normal component of the impulse
+ multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof2(deltaV_normal, impulse.dot(cti.m_normal));
+ // apply tangential component of the impulse
+ const btScalar* deltaV_t1 = &m_anchor->jacobianData_t1.m_deltaVelocitiesUnitImpulse[0];
+ multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof2(deltaV_t1, impulse.dot(m_anchor->t1));
+ const btScalar* deltaV_t2 = &m_anchor->jacobianData_t2.m_deltaVelocitiesUnitImpulse[0];
+ multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof2(deltaV_t2, impulse.dot(m_anchor->t2));
+ }
+ }
+ return residualSquare;
}
btVector3 btDeformableNodeAnchorConstraint::getVb() const
{
- return m_anchor->m_node->m_v;
+ return m_anchor->m_node->m_v;
}
void btDeformableNodeAnchorConstraint::applyImpulse(const btVector3& impulse)
{
- btVector3 dv = impulse * m_anchor->m_c2;
- m_anchor->m_node->m_v -= dv;
+ btVector3 dv = impulse * m_anchor->m_c2;
+ m_anchor->m_node->m_v -= dv;
}
/* ================ Deformable vs. Rigid =================== */
btDeformableRigidContactConstraint::btDeformableRigidContactConstraint(const btSoftBody::DeformableRigidContact& c, const btContactSolverInfo& infoGlobal)
-: m_contact(&c)
-, btDeformableContactConstraint(c.m_cti.m_normal, infoGlobal)
+ : m_contact(&c), btDeformableContactConstraint(c.m_cti.m_normal, infoGlobal)
{
- m_total_normal_dv.setZero();
- m_total_tangent_dv.setZero();
- // The magnitude of penetration is the depth of penetration.
- m_penetration = c.m_cti.m_offset;
-// m_penetration = btMin(btScalar(0),c.m_cti.m_offset);
+ m_total_normal_dv.setZero();
+ m_total_tangent_dv.setZero();
+ // The magnitude of penetration is the depth of penetration.
+ m_penetration = c.m_cti.m_offset;
+ m_total_split_impulse = 0;
+ m_binding = false;
}
btDeformableRigidContactConstraint::btDeformableRigidContactConstraint(const btDeformableRigidContactConstraint& other)
-: m_contact(other.m_contact)
-, btDeformableContactConstraint(other)
-, m_penetration(other.m_penetration)
+ : m_contact(other.m_contact), btDeformableContactConstraint(other), m_penetration(other.m_penetration), m_total_split_impulse(other.m_total_split_impulse), m_binding(other.m_binding)
{
- m_total_normal_dv = other.m_total_normal_dv;
- m_total_tangent_dv = other.m_total_tangent_dv;
+ m_total_normal_dv = other.m_total_normal_dv;
+ m_total_tangent_dv = other.m_total_tangent_dv;
}
-
btVector3 btDeformableRigidContactConstraint::getVa() const
{
- const btSoftBody::sCti& cti = m_contact->m_cti;
- btVector3 va(0, 0, 0);
- if (cti.m_colObj->hasContactResponse())
- {
- btRigidBody* rigidCol = 0;
- btMultiBodyLinkCollider* multibodyLinkCol = 0;
-
- // grab the velocity of the rigid body
- if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
- {
- rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
- va = rigidCol ? (rigidCol->getVelocityInLocalPoint(m_contact->m_c1)) : btVector3(0, 0, 0);
- }
- else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
- {
- multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
- if (multibodyLinkCol)
- {
- const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
- const btScalar* J_n = &m_contact->jacobianData_normal.m_jacobians[0];
- const btScalar* J_t1 = &m_contact->jacobianData_t1.m_jacobians[0];
- const btScalar* J_t2 = &m_contact->jacobianData_t2.m_jacobians[0];
- const btScalar* local_v = multibodyLinkCol->m_multiBody->getVelocityVector();
- const btScalar* local_dv = multibodyLinkCol->m_multiBody->getDeltaVelocityVector();
- // add in the normal component of the va
- btScalar vel = 0.0;
- for (int k = 0; k < ndof; ++k)
- {
- vel += (local_v[k]+local_dv[k]) * J_n[k];
- }
- va = cti.m_normal * vel;
- // add in the tangential components of the va
- vel = 0.0;
- for (int k = 0; k < ndof; ++k)
- {
- vel += (local_v[k]+local_dv[k]) * J_t1[k];
- }
- va += m_contact->t1 * vel;
- vel = 0.0;
- for (int k = 0; k < ndof; ++k)
- {
- vel += (local_v[k]+local_dv[k]) * J_t2[k];
- }
- va += m_contact->t2 * vel;
- }
- }
- }
- return va;
+ const btSoftBody::sCti& cti = m_contact->m_cti;
+ btVector3 va(0, 0, 0);
+ if (cti.m_colObj->hasContactResponse())
+ {
+ btRigidBody* rigidCol = 0;
+ btMultiBodyLinkCollider* multibodyLinkCol = 0;
+
+ // grab the velocity of the rigid body
+ if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
+ {
+ rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
+ va = rigidCol ? (rigidCol->getVelocityInLocalPoint(m_contact->m_c1)) : btVector3(0, 0, 0);
+ }
+ else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
+ {
+ multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
+ if (multibodyLinkCol)
+ {
+ const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
+ const btScalar* J_n = &m_contact->jacobianData_normal.m_jacobians[0];
+ const btScalar* J_t1 = &m_contact->jacobianData_t1.m_jacobians[0];
+ const btScalar* J_t2 = &m_contact->jacobianData_t2.m_jacobians[0];
+ const btScalar* local_v = multibodyLinkCol->m_multiBody->getVelocityVector();
+ const btScalar* local_dv = multibodyLinkCol->m_multiBody->getDeltaVelocityVector();
+ // add in the normal component of the va
+ btScalar vel = 0.0;
+ for (int k = 0; k < ndof; ++k)
+ {
+ vel += (local_v[k] + local_dv[k]) * J_n[k];
+ }
+ va = cti.m_normal * vel;
+ // add in the tangential components of the va
+ vel = 0.0;
+ for (int k = 0; k < ndof; ++k)
+ {
+ vel += (local_v[k] + local_dv[k]) * J_t1[k];
+ }
+ va += m_contact->t1 * vel;
+ vel = 0.0;
+ for (int k = 0; k < ndof; ++k)
+ {
+ vel += (local_v[k] + local_dv[k]) * J_t2[k];
+ }
+ va += m_contact->t2 * vel;
+ }
+ }
+ }
+ return va;
+}
+
+btVector3 btDeformableRigidContactConstraint::getSplitVa() const
+{
+ const btSoftBody::sCti& cti = m_contact->m_cti;
+ btVector3 va(0, 0, 0);
+ if (cti.m_colObj->hasContactResponse())
+ {
+ btRigidBody* rigidCol = 0;
+ btMultiBodyLinkCollider* multibodyLinkCol = 0;
+
+ // grab the velocity of the rigid body
+ if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
+ {
+ rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
+ va = rigidCol ? (rigidCol->getPushVelocityInLocalPoint(m_contact->m_c1)) : btVector3(0, 0, 0);
+ }
+ else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
+ {
+ multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
+ if (multibodyLinkCol)
+ {
+ const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
+ const btScalar* J_n = &m_contact->jacobianData_normal.m_jacobians[0];
+ const btScalar* J_t1 = &m_contact->jacobianData_t1.m_jacobians[0];
+ const btScalar* J_t2 = &m_contact->jacobianData_t2.m_jacobians[0];
+ const btScalar* local_split_v = multibodyLinkCol->m_multiBody->getSplitVelocityVector();
+ // add in the normal component of the va
+ btScalar vel = 0.0;
+ for (int k = 0; k < ndof; ++k)
+ {
+ vel += local_split_v[k] * J_n[k];
+ }
+ va = cti.m_normal * vel;
+ // add in the tangential components of the va
+ vel = 0.0;
+ for (int k = 0; k < ndof; ++k)
+ {
+ vel += local_split_v[k] * J_t1[k];
+ }
+ va += m_contact->t1 * vel;
+ vel = 0.0;
+ for (int k = 0; k < ndof; ++k)
+ {
+ vel += local_split_v[k] * J_t2[k];
+ }
+ va += m_contact->t2 * vel;
+ }
+ }
+ }
+ return va;
}
btScalar btDeformableRigidContactConstraint::solveConstraint(const btContactSolverInfo& infoGlobal)
{
- const btSoftBody::sCti& cti = m_contact->m_cti;
- btVector3 va = getVa();
- btVector3 vb = getVb();
- btVector3 vr = vb - va;
- btScalar dn = btDot(vr, cti.m_normal) + m_penetration * infoGlobal.m_deformable_erp / infoGlobal.m_timeStep;
- // dn is the normal component of velocity diffrerence. Approximates the residual. // todo xuchenhan@: this prob needs to be scaled by dt
- btScalar residualSquare = dn*dn;
- btVector3 impulse = m_contact->m_c0 * (vr + m_penetration * infoGlobal.m_deformable_erp / infoGlobal.m_timeStep * cti.m_normal) ;
- const btVector3 impulse_normal = m_contact->m_c0 * (cti.m_normal * dn);
- btVector3 impulse_tangent = impulse - impulse_normal;
- btVector3 old_total_tangent_dv = m_total_tangent_dv;
- // m_c2 is the inverse mass of the deformable node/face
- m_total_normal_dv -= impulse_normal * m_contact->m_c2;
- m_total_tangent_dv -= impulse_tangent * m_contact->m_c2;
-
- if (m_total_normal_dv.dot(cti.m_normal) < 0)
- {
- // separating in the normal direction
- m_static = false;
- m_total_tangent_dv = btVector3(0,0,0);
- impulse_tangent.setZero();
- }
- else
- {
- if (m_total_normal_dv.norm() * m_contact->m_c3 < m_total_tangent_dv.norm())
- {
- // dynamic friction
- // with dynamic friction, the impulse are still applied to the two objects colliding, however, it does not pose a constraint in the cg solve, hence the change to dv merely serves to update velocity in the contact iterations.
- m_static = false;
- if (m_total_tangent_dv.safeNorm() < SIMD_EPSILON)
- {
- m_total_tangent_dv = btVector3(0,0,0);
- }
- else
- {
- m_total_tangent_dv = m_total_tangent_dv.normalized() * m_total_normal_dv.safeNorm() * m_contact->m_c3;
- }
- impulse_tangent = -btScalar(1)/m_contact->m_c2 * (m_total_tangent_dv - old_total_tangent_dv);
- }
- else
- {
- // static friction
- m_static = true;
- }
- }
- impulse = impulse_normal + impulse_tangent;
- // apply impulse to deformable nodes involved and change their velocities
- applyImpulse(impulse);
- if (residualSquare < 1e-7)
- return residualSquare;
- // apply impulse to the rigid/multibodies involved and change their velocities
- if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
- {
- btRigidBody* rigidCol = 0;
- rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
- if (rigidCol)
- {
- rigidCol->applyImpulse(impulse, m_contact->m_c1);
- }
- }
- else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
- {
- btMultiBodyLinkCollider* multibodyLinkCol = 0;
- multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
- if (multibodyLinkCol)
- {
- const btScalar* deltaV_normal = &m_contact->jacobianData_normal.m_deltaVelocitiesUnitImpulse[0];
- // apply normal component of the impulse
- multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof2(deltaV_normal, impulse.dot(cti.m_normal));
- if (impulse_tangent.norm() > SIMD_EPSILON)
- {
- // apply tangential component of the impulse
- const btScalar* deltaV_t1 = &m_contact->jacobianData_t1.m_deltaVelocitiesUnitImpulse[0];
- multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof2(deltaV_t1, impulse.dot(m_contact->t1));
- const btScalar* deltaV_t2 = &m_contact->jacobianData_t2.m_deltaVelocitiesUnitImpulse[0];
- multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof2(deltaV_t2, impulse.dot(m_contact->t2));
- }
- }
- }
-// va = getVa();
-// vb = getVb();
-// vr = vb - va;
-// btScalar dn1 = btDot(vr, cti.m_normal) / 150;
-// m_penetration += dn1;
- return residualSquare;
+ const btSoftBody::sCti& cti = m_contact->m_cti;
+ btVector3 va = getVa();
+ btVector3 vb = getVb();
+ btVector3 vr = vb - va;
+ btScalar dn = btDot(vr, cti.m_normal) + m_total_normal_dv.dot(cti.m_normal) * infoGlobal.m_deformable_cfm;
+ if (m_penetration > 0)
+ {
+ dn += m_penetration / infoGlobal.m_timeStep;
+ }
+ if (!infoGlobal.m_splitImpulse)
+ {
+ dn += m_penetration * infoGlobal.m_deformable_erp / infoGlobal.m_timeStep;
+ }
+ // dn is the normal component of velocity diffrerence. Approximates the residual. // todo xuchenhan@: this prob needs to be scaled by dt
+ btVector3 impulse = m_contact->m_c0 * (vr + m_total_normal_dv * infoGlobal.m_deformable_cfm + ((m_penetration > 0) ? m_penetration / infoGlobal.m_timeStep * cti.m_normal : btVector3(0, 0, 0)));
+ if (!infoGlobal.m_splitImpulse)
+ {
+ impulse += m_contact->m_c0 * (m_penetration * infoGlobal.m_deformable_erp / infoGlobal.m_timeStep * cti.m_normal);
+ }
+ btVector3 impulse_normal = m_contact->m_c0 * (cti.m_normal * dn);
+ btVector3 impulse_tangent = impulse - impulse_normal;
+ if (dn > 0)
+ {
+ return 0;
+ }
+ m_binding = true;
+ btScalar residualSquare = dn * dn;
+ btVector3 old_total_tangent_dv = m_total_tangent_dv;
+ // m_c5 is the inverse mass of the deformable node/face
+ m_total_normal_dv -= m_contact->m_c5 * impulse_normal;
+ m_total_tangent_dv -= m_contact->m_c5 * impulse_tangent;
+
+ if (m_total_normal_dv.dot(cti.m_normal) < 0)
+ {
+ // separating in the normal direction
+ m_binding = false;
+ m_static = false;
+ impulse_tangent.setZero();
+ }
+ else
+ {
+ if (m_total_normal_dv.norm() * m_contact->m_c3 < m_total_tangent_dv.norm())
+ {
+ // dynamic friction
+ // with dynamic friction, the impulse are still applied to the two objects colliding, however, it does not pose a constraint in the cg solve, hence the change to dv merely serves to update velocity in the contact iterations.
+ m_static = false;
+ if (m_total_tangent_dv.safeNorm() < SIMD_EPSILON)
+ {
+ m_total_tangent_dv = btVector3(0, 0, 0);
+ }
+ else
+ {
+ m_total_tangent_dv = m_total_tangent_dv.normalized() * m_total_normal_dv.safeNorm() * m_contact->m_c3;
+ }
+ // impulse_tangent = -btScalar(1)/m_contact->m_c2 * (m_total_tangent_dv - old_total_tangent_dv);
+ impulse_tangent = m_contact->m_c5.inverse() * (old_total_tangent_dv - m_total_tangent_dv);
+ }
+ else
+ {
+ // static friction
+ m_static = true;
+ }
+ }
+ impulse = impulse_normal + impulse_tangent;
+ // apply impulse to deformable nodes involved and change their velocities
+ applyImpulse(impulse);
+ // apply impulse to the rigid/multibodies involved and change their velocities
+ if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
+ {
+ btRigidBody* rigidCol = 0;
+ rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
+ if (rigidCol)
+ {
+ rigidCol->applyImpulse(impulse, m_contact->m_c1);
+ }
+ }
+ else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
+ {
+ btMultiBodyLinkCollider* multibodyLinkCol = 0;
+ multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
+ if (multibodyLinkCol)
+ {
+ const btScalar* deltaV_normal = &m_contact->jacobianData_normal.m_deltaVelocitiesUnitImpulse[0];
+ // apply normal component of the impulse
+ multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof2(deltaV_normal, impulse.dot(cti.m_normal));
+ if (impulse_tangent.norm() > SIMD_EPSILON)
+ {
+ // apply tangential component of the impulse
+ const btScalar* deltaV_t1 = &m_contact->jacobianData_t1.m_deltaVelocitiesUnitImpulse[0];
+ multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof2(deltaV_t1, impulse.dot(m_contact->t1));
+ const btScalar* deltaV_t2 = &m_contact->jacobianData_t2.m_deltaVelocitiesUnitImpulse[0];
+ multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof2(deltaV_t2, impulse.dot(m_contact->t2));
+ }
+ }
+ }
+ return residualSquare;
+}
+
+btScalar btDeformableRigidContactConstraint::solveSplitImpulse(const btContactSolverInfo& infoGlobal)
+{
+ btScalar MAX_PENETRATION_CORRECTION = infoGlobal.m_deformable_maxErrorReduction;
+ const btSoftBody::sCti& cti = m_contact->m_cti;
+ btVector3 vb = getSplitVb();
+ btVector3 va = getSplitVa();
+ btScalar p = m_penetration;
+ if (p > 0)
+ {
+ return 0;
+ }
+ btVector3 vr = vb - va;
+ btScalar dn = btDot(vr, cti.m_normal) + p * infoGlobal.m_deformable_erp / infoGlobal.m_timeStep;
+ if (dn > 0)
+ {
+ return 0;
+ }
+ if (m_total_split_impulse + dn > MAX_PENETRATION_CORRECTION)
+ {
+ dn = MAX_PENETRATION_CORRECTION - m_total_split_impulse;
+ }
+ if (m_total_split_impulse + dn < -MAX_PENETRATION_CORRECTION)
+ {
+ dn = -MAX_PENETRATION_CORRECTION - m_total_split_impulse;
+ }
+ m_total_split_impulse += dn;
+
+ btScalar residualSquare = dn * dn;
+ const btVector3 impulse = m_contact->m_c0 * (cti.m_normal * dn);
+ applySplitImpulse(impulse);
+
+ // apply split impulse to the rigid/multibodies involved and change their velocities
+ if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
+ {
+ btRigidBody* rigidCol = 0;
+ rigidCol = (btRigidBody*)btRigidBody::upcast(cti.m_colObj);
+ if (rigidCol)
+ {
+ rigidCol->applyPushImpulse(impulse, m_contact->m_c1);
+ }
+ }
+ else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
+ {
+ btMultiBodyLinkCollider* multibodyLinkCol = 0;
+ multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
+ if (multibodyLinkCol)
+ {
+ const btScalar* deltaV_normal = &m_contact->jacobianData_normal.m_deltaVelocitiesUnitImpulse[0];
+ // apply normal component of the impulse
+ multibodyLinkCol->m_multiBody->applyDeltaSplitVeeMultiDof(deltaV_normal, impulse.dot(cti.m_normal));
+ }
+ }
+ return residualSquare;
}
/* ================ Node vs. Rigid =================== */
btDeformableNodeRigidContactConstraint::btDeformableNodeRigidContactConstraint(const btSoftBody::DeformableNodeRigidContact& contact, const btContactSolverInfo& infoGlobal)
- : m_node(contact.m_node)
- , btDeformableRigidContactConstraint(contact, infoGlobal)
- {
- }
+ : m_node(contact.m_node), btDeformableRigidContactConstraint(contact, infoGlobal)
+{
+}
btDeformableNodeRigidContactConstraint::btDeformableNodeRigidContactConstraint(const btDeformableNodeRigidContactConstraint& other)
-: m_node(other.m_node)
-, btDeformableRigidContactConstraint(other)
+ : m_node(other.m_node), btDeformableRigidContactConstraint(other)
{
}
btVector3 btDeformableNodeRigidContactConstraint::getVb() const
{
- return m_node->m_v;
+ return m_node->m_v;
}
+btVector3 btDeformableNodeRigidContactConstraint::getSplitVb() const
+{
+ return m_node->m_splitv;
+}
btVector3 btDeformableNodeRigidContactConstraint::getDv(const btSoftBody::Node* node) const
{
- return m_total_normal_dv + m_total_tangent_dv;
+ return m_total_normal_dv + m_total_tangent_dv;
}
void btDeformableNodeRigidContactConstraint::applyImpulse(const btVector3& impulse)
{
- const btSoftBody::DeformableNodeRigidContact* contact = getContact();
- btVector3 dv = impulse * contact->m_c2;
- contact->m_node->m_v -= dv;
+ const btSoftBody::DeformableNodeRigidContact* contact = getContact();
+ btVector3 dv = contact->m_c5 * impulse;
+ contact->m_node->m_v -= dv;
+}
+
+void btDeformableNodeRigidContactConstraint::applySplitImpulse(const btVector3& impulse)
+{
+ const btSoftBody::DeformableNodeRigidContact* contact = getContact();
+ btVector3 dv = contact->m_c5 * impulse;
+ contact->m_node->m_splitv -= dv;
}
/* ================ Face vs. Rigid =================== */
btDeformableFaceRigidContactConstraint::btDeformableFaceRigidContactConstraint(const btSoftBody::DeformableFaceRigidContact& contact, const btContactSolverInfo& infoGlobal, bool useStrainLimiting)
-: m_face(contact.m_face)
-, m_useStrainLimiting(useStrainLimiting)
-, btDeformableRigidContactConstraint(contact, infoGlobal)
+ : m_face(contact.m_face), m_useStrainLimiting(useStrainLimiting), btDeformableRigidContactConstraint(contact, infoGlobal)
{
}
btDeformableFaceRigidContactConstraint::btDeformableFaceRigidContactConstraint(const btDeformableFaceRigidContactConstraint& other)
-: m_face(other.m_face)
-, m_useStrainLimiting(other.m_useStrainLimiting)
-, btDeformableRigidContactConstraint(other)
+ : m_face(other.m_face), m_useStrainLimiting(other.m_useStrainLimiting), btDeformableRigidContactConstraint(other)
{
}
btVector3 btDeformableFaceRigidContactConstraint::getVb() const
{
- const btSoftBody::DeformableFaceRigidContact* contact = getContact();
- btVector3 vb = m_face->m_n[0]->m_v * contact->m_bary[0] + m_face->m_n[1]->m_v * contact->m_bary[1] + m_face->m_n[2]->m_v * contact->m_bary[2];
- return vb;
+ const btSoftBody::DeformableFaceRigidContact* contact = getContact();
+ btVector3 vb = m_face->m_n[0]->m_v * contact->m_bary[0] + m_face->m_n[1]->m_v * contact->m_bary[1] + m_face->m_n[2]->m_v * contact->m_bary[2];
+ return vb;
}
-
btVector3 btDeformableFaceRigidContactConstraint::getDv(const btSoftBody::Node* node) const
{
- btVector3 face_dv = m_total_normal_dv + m_total_tangent_dv;
- const btSoftBody::DeformableFaceRigidContact* contact = getContact();
- if (m_face->m_n[0] == node)
- {
- return face_dv * contact->m_weights[0];
- }
- if (m_face->m_n[1] == node)
- {
- return face_dv * contact->m_weights[1];
- }
- btAssert(node == m_face->m_n[2]);
- return face_dv * contact->m_weights[2];
+ btVector3 face_dv = m_total_normal_dv + m_total_tangent_dv;
+ const btSoftBody::DeformableFaceRigidContact* contact = getContact();
+ if (m_face->m_n[0] == node)
+ {
+ return face_dv * contact->m_weights[0];
+ }
+ if (m_face->m_n[1] == node)
+ {
+ return face_dv * contact->m_weights[1];
+ }
+ btAssert(node == m_face->m_n[2]);
+ return face_dv * contact->m_weights[2];
}
void btDeformableFaceRigidContactConstraint::applyImpulse(const btVector3& impulse)
{
- const btSoftBody::DeformableFaceRigidContact* contact = getContact();
- btVector3 dv = impulse * contact->m_c2;
- btSoftBody::Face* face = contact->m_face;
-
- btVector3& v0 = face->m_n[0]->m_v;
- btVector3& v1 = face->m_n[1]->m_v;
- btVector3& v2 = face->m_n[2]->m_v;
- const btScalar& im0 = face->m_n[0]->m_im;
- const btScalar& im1 = face->m_n[1]->m_im;
- const btScalar& im2 = face->m_n[2]->m_im;
- if (im0 > 0)
- v0 -= dv * contact->m_weights[0];
- if (im1 > 0)
- v1 -= dv * contact->m_weights[1];
- if (im2 > 0)
- v2 -= dv * contact->m_weights[2];
+ const btSoftBody::DeformableFaceRigidContact* contact = getContact();
+ btVector3 dv = impulse * contact->m_c2;
+ btSoftBody::Face* face = contact->m_face;
+
+ btVector3& v0 = face->m_n[0]->m_v;
+ btVector3& v1 = face->m_n[1]->m_v;
+ btVector3& v2 = face->m_n[2]->m_v;
+ const btScalar& im0 = face->m_n[0]->m_im;
+ const btScalar& im1 = face->m_n[1]->m_im;
+ const btScalar& im2 = face->m_n[2]->m_im;
+ if (im0 > 0)
+ v0 -= dv * contact->m_weights[0];
+ if (im1 > 0)
+ v1 -= dv * contact->m_weights[1];
+ if (im2 > 0)
+ v2 -= dv * contact->m_weights[2];
if (m_useStrainLimiting)
{
- btScalar relaxation = 1./btScalar(m_infoGlobal->m_numIterations);
- btScalar m01 = (relaxation/(im0 + im1));
- btScalar m02 = (relaxation/(im0 + im2));
- btScalar m12 = (relaxation/(im1 + im2));
- #ifdef USE_STRAIN_RATE_LIMITING
+ btScalar relaxation = 1. / btScalar(m_infoGlobal->m_numIterations);
+ btScalar m01 = (relaxation / (im0 + im1));
+ btScalar m02 = (relaxation / (im0 + im2));
+ btScalar m12 = (relaxation / (im1 + im2));
+#ifdef USE_STRAIN_RATE_LIMITING
// apply strain limiting to prevent the new velocity to change the current length of the edge by more than 1%.
btScalar p = 0.01;
btVector3& x0 = face->m_n[0]->m_x;
btVector3& x1 = face->m_n[1]->m_x;
btVector3& x2 = face->m_n[2]->m_x;
- const btVector3 x_diff[3] = {x1-x0, x2-x0, x2-x1};
- const btVector3 v_diff[3] = {v1-v0, v2-v0, v2-v1};
+ const btVector3 x_diff[3] = {x1 - x0, x2 - x0, x2 - x1};
+ const btVector3 v_diff[3] = {v1 - v0, v2 - v0, v2 - v1};
btVector3 u[3];
btScalar x_diff_dot_u, dn[3];
btScalar dt = m_infoGlobal->m_timeStep;
@@ -404,172 +520,201 @@ void btDeformableFaceRigidContactConstraint::applyImpulse(const btVector3& impul
{
btScalar x_diff_norm = x_diff[i].safeNorm();
btScalar x_diff_norm_new = (x_diff[i] + v_diff[i] * dt).safeNorm();
- btScalar strainRate = x_diff_norm_new/x_diff_norm;
+ btScalar strainRate = x_diff_norm_new / x_diff_norm;
u[i] = v_diff[i];
u[i].safeNormalize();
- if (x_diff_norm == 0 || (1-p <= strainRate && strainRate <= 1+p))
+ if (x_diff_norm == 0 || (1 - p <= strainRate && strainRate <= 1 + p))
{
dn[i] = 0;
continue;
}
x_diff_dot_u = btDot(x_diff[i], u[i]);
btScalar s;
- if (1-p > strainRate)
+ if (1 - p > strainRate)
{
- s = 1/dt * (-x_diff_dot_u - btSqrt(x_diff_dot_u*x_diff_dot_u + (p*p-2*p) * x_diff_norm * x_diff_norm));
+ s = 1 / dt * (-x_diff_dot_u - btSqrt(x_diff_dot_u * x_diff_dot_u + (p * p - 2 * p) * x_diff_norm * x_diff_norm));
}
else
{
- s = 1/dt * (-x_diff_dot_u + btSqrt(x_diff_dot_u*x_diff_dot_u + (p*p+2*p) * x_diff_norm * x_diff_norm));
+ s = 1 / dt * (-x_diff_dot_u + btSqrt(x_diff_dot_u * x_diff_dot_u + (p * p + 2 * p) * x_diff_norm * x_diff_norm));
}
// x_diff_norm_new = (x_diff[i] + s * u[i] * dt).safeNorm();
// strainRate = x_diff_norm_new/x_diff_norm;
dn[i] = s - v_diff[i].safeNorm();
}
- btVector3 dv0 = im0 * (m01 * u[0]*(-dn[0]) + m02 * u[1]*-(dn[1]));
- btVector3 dv1 = im1 * (m01 * u[0]*(dn[0]) + m12 * u[2]*(-dn[2]));
- btVector3 dv2 = im2 * (m12 * u[2]*(dn[2]) + m02 * u[1]*(dn[1]));
- #else
+ btVector3 dv0 = im0 * (m01 * u[0] * (-dn[0]) + m02 * u[1] * -(dn[1]));
+ btVector3 dv1 = im1 * (m01 * u[0] * (dn[0]) + m12 * u[2] * (-dn[2]));
+ btVector3 dv2 = im2 * (m12 * u[2] * (dn[2]) + m02 * u[1] * (dn[1]));
+#else
// apply strain limiting to prevent undamped modes
- btVector3 dv0 = im0 * (m01 * (v1-v0) + m02 * (v2-v0));
- btVector3 dv1 = im1 * (m01 * (v0-v1) + m12 * (v2-v1));
- btVector3 dv2 = im2 * (m12 * (v1-v2) + m02 * (v0-v2));
- #endif
+ btVector3 dv0 = im0 * (m01 * (v1 - v0) + m02 * (v2 - v0));
+ btVector3 dv1 = im1 * (m01 * (v0 - v1) + m12 * (v2 - v1));
+ btVector3 dv2 = im2 * (m12 * (v1 - v2) + m02 * (v0 - v2));
+#endif
v0 += dv0;
v1 += dv1;
v2 += dv2;
}
}
+btVector3 btDeformableFaceRigidContactConstraint::getSplitVb() const
+{
+ const btSoftBody::DeformableFaceRigidContact* contact = getContact();
+ btVector3 vb = (m_face->m_n[0]->m_splitv) * contact->m_bary[0] + (m_face->m_n[1]->m_splitv) * contact->m_bary[1] + (m_face->m_n[2]->m_splitv) * contact->m_bary[2];
+ return vb;
+}
+
+void btDeformableFaceRigidContactConstraint::applySplitImpulse(const btVector3& impulse)
+{
+ const btSoftBody::DeformableFaceRigidContact* contact = getContact();
+ btVector3 dv = impulse * contact->m_c2;
+ btSoftBody::Face* face = contact->m_face;
+ btVector3& v0 = face->m_n[0]->m_splitv;
+ btVector3& v1 = face->m_n[1]->m_splitv;
+ btVector3& v2 = face->m_n[2]->m_splitv;
+ const btScalar& im0 = face->m_n[0]->m_im;
+ const btScalar& im1 = face->m_n[1]->m_im;
+ const btScalar& im2 = face->m_n[2]->m_im;
+ if (im0 > 0)
+ {
+ v0 -= dv * contact->m_weights[0];
+ }
+ if (im1 > 0)
+ {
+ v1 -= dv * contact->m_weights[1];
+ }
+ if (im2 > 0)
+ {
+ v2 -= dv * contact->m_weights[2];
+ }
+}
+
/* ================ Face vs. Node =================== */
btDeformableFaceNodeContactConstraint::btDeformableFaceNodeContactConstraint(const btSoftBody::DeformableFaceNodeContact& contact, const btContactSolverInfo& infoGlobal)
-: m_node(contact.m_node)
-, m_face(contact.m_face)
-, m_contact(&contact)
-, btDeformableContactConstraint(contact.m_normal, infoGlobal)
+ : m_node(contact.m_node), m_face(contact.m_face), m_contact(&contact), btDeformableContactConstraint(contact.m_normal, infoGlobal)
{
- m_total_normal_dv.setZero();
- m_total_tangent_dv.setZero();
+ m_total_normal_dv.setZero();
+ m_total_tangent_dv.setZero();
}
btVector3 btDeformableFaceNodeContactConstraint::getVa() const
{
- return m_node->m_v;
+ return m_node->m_v;
}
btVector3 btDeformableFaceNodeContactConstraint::getVb() const
{
- const btSoftBody::DeformableFaceNodeContact* contact = getContact();
- btVector3 vb = m_face->m_n[0]->m_v * contact->m_bary[0] + m_face->m_n[1]->m_v * contact->m_bary[1] + m_face->m_n[2]->m_v * contact->m_bary[2];
- return vb;
+ const btSoftBody::DeformableFaceNodeContact* contact = getContact();
+ btVector3 vb = m_face->m_n[0]->m_v * contact->m_bary[0] + m_face->m_n[1]->m_v * contact->m_bary[1] + m_face->m_n[2]->m_v * contact->m_bary[2];
+ return vb;
}
btVector3 btDeformableFaceNodeContactConstraint::getDv(const btSoftBody::Node* n) const
{
- btVector3 dv = m_total_normal_dv + m_total_tangent_dv;
- if (n == m_node)
- return dv;
- const btSoftBody::DeformableFaceNodeContact* contact = getContact();
- if (m_face->m_n[0] == n)
- {
- return dv * contact->m_weights[0];
- }
- if (m_face->m_n[1] == n)
- {
- return dv * contact->m_weights[1];
- }
- btAssert(n == m_face->m_n[2]);
- return dv * contact->m_weights[2];
+ btVector3 dv = m_total_normal_dv + m_total_tangent_dv;
+ if (n == m_node)
+ return dv;
+ const btSoftBody::DeformableFaceNodeContact* contact = getContact();
+ if (m_face->m_n[0] == n)
+ {
+ return dv * contact->m_weights[0];
+ }
+ if (m_face->m_n[1] == n)
+ {
+ return dv * contact->m_weights[1];
+ }
+ btAssert(n == m_face->m_n[2]);
+ return dv * contact->m_weights[2];
}
btScalar btDeformableFaceNodeContactConstraint::solveConstraint(const btContactSolverInfo& infoGlobal)
{
- btVector3 va = getVa();
- btVector3 vb = getVb();
- btVector3 vr = vb - va;
- const btScalar dn = btDot(vr, m_contact->m_normal);
- // dn is the normal component of velocity diffrerence. Approximates the residual. // todo xuchenhan@: this prob needs to be scaled by dt
- btScalar residualSquare = dn*dn;
- btVector3 impulse = m_contact->m_c0 * vr;
- const btVector3 impulse_normal = m_contact->m_c0 * (m_contact->m_normal * dn);
- btVector3 impulse_tangent = impulse - impulse_normal;
-
- btVector3 old_total_tangent_dv = m_total_tangent_dv;
- // m_c2 is the inverse mass of the deformable node/face
- if (m_node->m_im > 0)
- {
- m_total_normal_dv -= impulse_normal * m_node->m_im;
- m_total_tangent_dv -= impulse_tangent * m_node->m_im;
- }
- else
- {
- m_total_normal_dv -= impulse_normal * m_contact->m_imf;
- m_total_tangent_dv -= impulse_tangent * m_contact->m_imf;
- }
-
- if (m_total_normal_dv.dot(m_contact->m_normal) > 0)
- {
- // separating in the normal direction
- m_static = false;
- m_total_tangent_dv = btVector3(0,0,0);
- impulse_tangent.setZero();
- }
- else
- {
- if (m_total_normal_dv.norm() * m_contact->m_friction < m_total_tangent_dv.norm())
- {
- // dynamic friction
- // with dynamic friction, the impulse are still applied to the two objects colliding, however, it does not pose a constraint in the cg solve, hence the change to dv merely serves to update velocity in the contact iterations.
- m_static = false;
- if (m_total_tangent_dv.safeNorm() < SIMD_EPSILON)
- {
- m_total_tangent_dv = btVector3(0,0,0);
- }
- else
- {
- m_total_tangent_dv = m_total_tangent_dv.normalized() * m_total_normal_dv.safeNorm() * m_contact->m_friction;
- }
- impulse_tangent = -btScalar(1)/m_node->m_im * (m_total_tangent_dv - old_total_tangent_dv);
- }
- else
- {
- // static friction
- m_static = true;
- }
- }
- impulse = impulse_normal + impulse_tangent;
- // apply impulse to deformable nodes involved and change their velocities
- applyImpulse(impulse);
- return residualSquare;
+ btVector3 va = getVa();
+ btVector3 vb = getVb();
+ btVector3 vr = vb - va;
+ const btScalar dn = btDot(vr, m_contact->m_normal);
+ // dn is the normal component of velocity diffrerence. Approximates the residual. // todo xuchenhan@: this prob needs to be scaled by dt
+ btScalar residualSquare = dn * dn;
+ btVector3 impulse = m_contact->m_c0 * vr;
+ const btVector3 impulse_normal = m_contact->m_c0 * (m_contact->m_normal * dn);
+ btVector3 impulse_tangent = impulse - impulse_normal;
+
+ btVector3 old_total_tangent_dv = m_total_tangent_dv;
+ // m_c2 is the inverse mass of the deformable node/face
+ if (m_node->m_im > 0)
+ {
+ m_total_normal_dv -= impulse_normal * m_node->m_im;
+ m_total_tangent_dv -= impulse_tangent * m_node->m_im;
+ }
+ else
+ {
+ m_total_normal_dv -= impulse_normal * m_contact->m_imf;
+ m_total_tangent_dv -= impulse_tangent * m_contact->m_imf;
+ }
+
+ if (m_total_normal_dv.dot(m_contact->m_normal) > 0)
+ {
+ // separating in the normal direction
+ m_static = false;
+ m_total_tangent_dv = btVector3(0, 0, 0);
+ impulse_tangent.setZero();
+ }
+ else
+ {
+ if (m_total_normal_dv.norm() * m_contact->m_friction < m_total_tangent_dv.norm())
+ {
+ // dynamic friction
+ // with dynamic friction, the impulse are still applied to the two objects colliding, however, it does not pose a constraint in the cg solve, hence the change to dv merely serves to update velocity in the contact iterations.
+ m_static = false;
+ if (m_total_tangent_dv.safeNorm() < SIMD_EPSILON)
+ {
+ m_total_tangent_dv = btVector3(0, 0, 0);
+ }
+ else
+ {
+ m_total_tangent_dv = m_total_tangent_dv.normalized() * m_total_normal_dv.safeNorm() * m_contact->m_friction;
+ }
+ impulse_tangent = -btScalar(1) / m_node->m_im * (m_total_tangent_dv - old_total_tangent_dv);
+ }
+ else
+ {
+ // static friction
+ m_static = true;
+ }
+ }
+ impulse = impulse_normal + impulse_tangent;
+ // apply impulse to deformable nodes involved and change their velocities
+ applyImpulse(impulse);
+ return residualSquare;
}
void btDeformableFaceNodeContactConstraint::applyImpulse(const btVector3& impulse)
{
- const btSoftBody::DeformableFaceNodeContact* contact = getContact();
- btVector3 dva = impulse * contact->m_node->m_im;
- btVector3 dvb = impulse * contact->m_imf;
- if (contact->m_node->m_im > 0)
- {
- contact->m_node->m_v += dva;
- }
-
- btSoftBody::Face* face = contact->m_face;
- btVector3& v0 = face->m_n[0]->m_v;
- btVector3& v1 = face->m_n[1]->m_v;
- btVector3& v2 = face->m_n[2]->m_v;
- const btScalar& im0 = face->m_n[0]->m_im;
- const btScalar& im1 = face->m_n[1]->m_im;
- const btScalar& im2 = face->m_n[2]->m_im;
- if (im0 > 0)
- {
- v0 -= dvb * contact->m_weights[0];
- }
- if (im1 > 0)
- {
- v1 -= dvb * contact->m_weights[1];
- }
- if (im2 > 0)
- {
- v2 -= dvb * contact->m_weights[2];
- }
+ const btSoftBody::DeformableFaceNodeContact* contact = getContact();
+ btVector3 dva = impulse * contact->m_node->m_im;
+ btVector3 dvb = impulse * contact->m_imf;
+ if (contact->m_node->m_im > 0)
+ {
+ contact->m_node->m_v += dva;
+ }
+
+ btSoftBody::Face* face = contact->m_face;
+ btVector3& v0 = face->m_n[0]->m_v;
+ btVector3& v1 = face->m_n[1]->m_v;
+ btVector3& v2 = face->m_n[2]->m_v;
+ const btScalar& im0 = face->m_n[0]->m_im;
+ const btScalar& im1 = face->m_n[1]->m_im;
+ const btScalar& im2 = face->m_n[2]->m_im;
+ if (im0 > 0)
+ {
+ v0 -= dvb * contact->m_weights[0];
+ }
+ if (im1 > 0)
+ {
+ v1 -= dvb * contact->m_weights[1];
+ }
+ if (im2 > 0)
+ {
+ v2 -= dvb * contact->m_weights[2];
+ }
}