Bart/bullet3
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

add strain rate limiting

Browse Source
This commit is contained in:
Xuchen Han
2019-12-31 14:04:18 -08:00
parent 79c1343b6a
commit d7442cee21
10 changed files with 116 additions and 79 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
src/BulletSoftBody/btDeformableBackwardEulerObjective.cpp
View File

@@ -186,9 +186,9 @@ void btDeformableBackwardEulerObjective::initialGuess(TVStack& dv, const TVStack
}
//set constraints as projections
void btDeformableBackwardEulerObjective::setConstraints()
void btDeformableBackwardEulerObjective::setConstraints(const btContactSolverInfo& infoGlobal)
{
m_projection.setConstraints();
m_projection.setConstraints(infoGlobal);
}
void btDeformableBackwardEulerObjective::applyDynamicFriction(TVStack& r)

2
src/BulletSoftBody/btDeformableBackwardEulerObjective.h
View File

@@ -79,7 +79,7 @@ public:
void updateVelocity(const TVStack& dv);
//set constraints as projections
void setConstraints();
void setConstraints(const btContactSolverInfo& infoGlobal);
// update the projections and project the residual
void project(TVStack& r)

4
src/BulletSoftBody/btDeformableBodySolver.cpp
View File

@@ -228,10 +228,10 @@ void btDeformableBodySolver::reinitialize(const btAlignedObjectArray<btSoftBody
m_objective->reinitialize(nodeUpdated, dt);
}
void btDeformableBodySolver::setConstraints()
void btDeformableBodySolver::setConstraints(const btContactSolverInfo& infoGlobal)
{
BT_PROFILE("setConstraint");
m_objective->setConstraints();
m_objective->setConstraints(infoGlobal);
}
btScalar btDeformableBodySolver::solveContactConstraints(btCollisionObject** deformableBodies,int numDeformableBodies)

2
src/BulletSoftBody/btDeformableBodySolver.h
View File

@@ -77,7 +77,7 @@ public:
void reinitialize(const btAlignedObjectArray<btSoftBody *>& softBodies, btScalar dt);
// set up contact constraints
void setConstraints();
void setConstraints(const btContactSolverInfo& infoGlobal);
// add in elastic forces and gravity to obtain v_{n+1}^* and calls predictDeformableMotion
virtual void predictMotion(btScalar solverdt);

87
src/BulletSoftBody/btDeformableContactConstraint.cpp
View File

@@ -15,9 +15,9 @@
#include "btDeformableContactConstraint.h"
/* ================ Deformable Node Anchor =================== */
btDeformableNodeAnchorConstraint::btDeformableNodeAnchorConstraint(const btSoftBody::DeformableNodeRigidAnchor& a)
btDeformableNodeAnchorConstraint::btDeformableNodeAnchorConstraint(const btSoftBody::DeformableNodeRigidAnchor& a, const btContactSolverInfo& infoGlobal)
: m_anchor(&a)
, btDeformableContactConstraint(a.m_cti.m_normal)
, btDeformableContactConstraint(a.m_cti.m_normal, infoGlobal)
{
}
@@ -134,9 +134,9 @@ void btDeformableNodeAnchorConstraint::applyImpulse(const btVector3& impulse)
}
/* ================ Deformable vs. Rigid =================== */
btDeformableRigidContactConstraint::btDeformableRigidContactConstraint(const btSoftBody::DeformableRigidContact& c)
btDeformableRigidContactConstraint::btDeformableRigidContactConstraint(const btSoftBody::DeformableRigidContact& c, const btContactSolverInfo& infoGlobal)
: m_contact(&c)
, btDeformableContactConstraint(c.m_cti.m_normal)
, btDeformableContactConstraint(c.m_cti.m_normal, infoGlobal)
{
m_total_normal_dv.setZero();
m_total_tangent_dv.setZero();
@@ -321,9 +321,9 @@ btScalar btDeformableRigidContactConstraint::solveSplitImpulse(const btContactSo
}
/* ================ Node vs. Rigid =================== */
btDeformableNodeRigidContactConstraint::btDeformableNodeRigidContactConstraint(const btSoftBody::DeformableNodeRigidContact& contact)
btDeformableNodeRigidContactConstraint::btDeformableNodeRigidContactConstraint(const btSoftBody::DeformableNodeRigidContact& contact, const btContactSolverInfo& infoGlobal)
: m_node(contact.m_node)
, btDeformableRigidContactConstraint(contact)
, btDeformableRigidContactConstraint(contact, infoGlobal)
{
}
@@ -359,9 +359,9 @@ void btDeformableNodeRigidContactConstraint::applySplitImpulse(const btVector3&
};
/* ================ Face vs. Rigid =================== */
btDeformableFaceRigidContactConstraint::btDeformableFaceRigidContactConstraint(const btSoftBody::DeformableFaceRigidContact& contact)
btDeformableFaceRigidContactConstraint::btDeformableFaceRigidContactConstraint(const btSoftBody::DeformableFaceRigidContact& contact, const btContactSolverInfo& infoGlobal)
: m_face(contact.m_face)
, btDeformableRigidContactConstraint(contact)
, btDeformableRigidContactConstraint(contact, infoGlobal)
{
}
@@ -413,19 +413,60 @@ void btDeformableFaceRigidContactConstraint::applyImpulse(const btVector3& impul
v1 -= dv * contact->m_weights[1];
if (im2 > 0)
v2 -= dv * contact->m_weights[2];
// apply strain limiting to prevent undamped modes
btScalar m01 = (btScalar(1)/(im0 + im1));
btScalar m02 = (btScalar(1)/(im0 + im2));
btScalar m12 = (btScalar(1)/(im1 + im2));
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));
v0 += dv0;
v1 += dv1;
v2 += dv2;
// 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};
btVector3 u[3];
btScalar x_diff_dot_u, dn[3];
btScalar dt = m_infoGlobal->m_timeStep;
for (int i = 0; i < 3; ++i)
{
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;
u[i] = v_diff[i];
u[i].safeNormalize();
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)
{
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));
}
// 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();
}
btScalar relaxation = 0.5;
// apply strain limiting to prevent undamped modes
btScalar m01 = (relaxation/(im0 + im1));
btScalar m02 = (relaxation/(im0 + im2));
btScalar m12 = (relaxation/(im1 + im2));
// 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));
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]));
v0 += dv0;
v1 += dv1;
v2 += dv2;
}
void btDeformableFaceRigidContactConstraint::applySplitImpulse(const btVector3& impulse)
@@ -449,11 +490,11 @@ void btDeformableFaceRigidContactConstraint::applySplitImpulse(const btVector3&
}
/* ================ Face vs. Node =================== */
btDeformableFaceNodeContactConstraint::btDeformableFaceNodeContactConstraint(const btSoftBody::DeformableFaceNodeContact& contact)
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)
, btDeformableContactConstraint(contact.m_normal, infoGlobal)
{
m_total_normal_dv.setZero();
m_total_tangent_dv.setZero();

79
src/BulletSoftBody/btDeformableContactConstraint.h
View File

@@ -24,26 +24,28 @@ public:
// True if the friction is static
// False if the friction is dynamic
bool m_static;
// normal of the contact
btVector3 m_normal;
btDeformableContactConstraint(const btVector3& normal): m_static(false), m_normal(normal)
{
}
btDeformableContactConstraint(bool isStatic, const btVector3& normal): m_static(isStatic), m_normal(normal)
{
}
btDeformableContactConstraint(const btDeformableContactConstraint& other)
: m_static(other.m_static)
, m_normal(other.m_normal)
{
}
btDeformableContactConstraint(){}
const btContactSolverInfo* m_infoGlobal;
// normal of the contact
btVector3 m_normal;
btDeformableContactConstraint(const btVector3& normal, const btContactSolverInfo& infoGlobal): m_static(false), m_normal(normal), m_infoGlobal(&infoGlobal)
{
}
btDeformableContactConstraint(bool isStatic, const btVector3& normal, const btContactSolverInfo& infoGlobal): m_static(isStatic), m_normal(normal), m_infoGlobal(&infoGlobal)
{
}
btDeformableContactConstraint(){}
btDeformableContactConstraint(const btDeformableContactConstraint& other)
: m_static(other.m_static)
, m_normal(other.m_normal)
, m_infoGlobal(other.m_infoGlobal)
{
}
virtual ~btDeformableContactConstraint(){}
// solve the constraint with inelastic impulse and return the error, which is the square of normal component of velocity diffrerence
@@ -79,17 +81,14 @@ class btDeformableStaticConstraint : public btDeformableContactConstraint
public:
const btSoftBody::Node* m_node;
btDeformableStaticConstraint(){}
btDeformableStaticConstraint(const btSoftBody::Node* node): m_node(node), btDeformableContactConstraint(false, btVector3(0,0,0))
btDeformableStaticConstraint(const btSoftBody::Node* node, const btContactSolverInfo& infoGlobal): m_node(node), btDeformableContactConstraint(false, btVector3(0,0,0), infoGlobal)
{
}
btDeformableStaticConstraint(){}
btDeformableStaticConstraint(const btDeformableStaticConstraint& other)
: m_node(other.m_node)
, btDeformableContactConstraint(other)
{
}
virtual ~btDeformableStaticConstraint(){}
@@ -130,10 +129,10 @@ class btDeformableNodeAnchorConstraint : public btDeformableContactConstraint
{
public:
const btSoftBody::DeformableNodeRigidAnchor* m_anchor;
btDeformableNodeAnchorConstraint(){}
btDeformableNodeAnchorConstraint(const btSoftBody::DeformableNodeRigidAnchor& c);
btDeformableNodeAnchorConstraint(const btSoftBody::DeformableNodeRigidAnchor& c, const btContactSolverInfo& infoGlobal);
btDeformableNodeAnchorConstraint(const btDeformableNodeAnchorConstraint& other);
btDeformableNodeAnchorConstraint(){}
virtual ~btDeformableNodeAnchorConstraint()
{
}
@@ -169,10 +168,10 @@ public:
btVector3 m_total_tangent_dv;
btScalar m_penetration;
const btSoftBody::DeformableRigidContact* m_contact;
btDeformableRigidContactConstraint(){}
btDeformableRigidContactConstraint(const btSoftBody::DeformableRigidContact& c);
btDeformableRigidContactConstraint(const btSoftBody::DeformableRigidContact& c, const btContactSolverInfo& infoGlobal);
btDeformableRigidContactConstraint(const btDeformableRigidContactConstraint& other);
btDeformableRigidContactConstraint(){}
virtual ~btDeformableRigidContactConstraint()
{
}
@@ -197,11 +196,10 @@ class btDeformableNodeRigidContactConstraint : public btDeformableRigidContactCo
public:
// the deformable node in contact
const btSoftBody::Node* m_node;
btDeformableNodeRigidContactConstraint(){}
btDeformableNodeRigidContactConstraint(const btSoftBody::DeformableNodeRigidContact& contact);
btDeformableNodeRigidContactConstraint(const btSoftBody::DeformableNodeRigidContact& contact, const btContactSolverInfo& infoGlobal);
btDeformableNodeRigidContactConstraint(const btDeformableNodeRigidContactConstraint& other);
btDeformableNodeRigidContactConstraint(){}
virtual ~btDeformableNodeRigidContactConstraint()
{
}
@@ -228,10 +226,9 @@ class btDeformableFaceRigidContactConstraint : public btDeformableRigidContactCo
{
public:
const btSoftBody::Face* m_face;
btDeformableFaceRigidContactConstraint(){}
btDeformableFaceRigidContactConstraint(const btSoftBody::DeformableFaceRigidContact& contact);
btDeformableFaceRigidContactConstraint(const btSoftBody::DeformableFaceRigidContact& contact, const btContactSolverInfo& infoGlobal);
btDeformableFaceRigidContactConstraint(const btDeformableFaceRigidContactConstraint& other);
btDeformableFaceRigidContactConstraint(){}
virtual ~btDeformableFaceRigidContactConstraint()
{
}
@@ -263,10 +260,8 @@ public:
btVector3 m_total_normal_dv;
btVector3 m_total_tangent_dv;
btDeformableFaceNodeContactConstraint(){}
btDeformableFaceNodeContactConstraint(const btSoftBody::DeformableFaceNodeContact& contact);
btDeformableFaceNodeContactConstraint(const btSoftBody::DeformableFaceNodeContact& contact, const btContactSolverInfo& infoGlobal);
btDeformableFaceNodeContactConstraint(){}
virtual ~btDeformableFaceNodeContactConstraint(){}
virtual btScalar solveConstraint();

12
src/BulletSoftBody/btDeformableContactProjection.cpp
View File

@@ -108,7 +108,7 @@ btScalar btDeformableContactProjection::solveSplitImpulse(const btContactSolverI
return residualSquare;
}
void btDeformableContactProjection::setConstraints()
void btDeformableContactProjection::setConstraints(const btContactSolverInfo& infoGlobal)
{
BT_PROFILE("setConstraints");
for (int i = 0; i < m_softBodies.size(); ++i)
@@ -124,7 +124,7 @@ void btDeformableContactProjection::setConstraints()
{
if (psb->m_nodes[j].m_im == 0)
{
btDeformableStaticConstraint static_constraint(&psb->m_nodes[j]);
btDeformableStaticConstraint static_constraint(&psb->m_nodes[j], infoGlobal);
m_staticConstraints[i].push_back(static_constraint);
}
}
@@ -139,7 +139,7 @@ void btDeformableContactProjection::setConstraints()
continue;
}
anchor.m_c1 = anchor.m_cti.m_colObj->getWorldTransform().getBasis() * anchor.m_local;
btDeformableNodeAnchorConstraint constraint(anchor);
btDeformableNodeAnchorConstraint constraint(anchor, infoGlobal);
m_nodeAnchorConstraints[i].push_back(constraint);
}
@@ -152,7 +152,7 @@ void btDeformableContactProjection::setConstraints()
{
continue;
}
btDeformableNodeRigidContactConstraint constraint(contact);
btDeformableNodeRigidContactConstraint constraint(contact, infoGlobal);
btVector3 va = constraint.getVa();
btVector3 vb = constraint.getVb();
const btVector3 vr = vb - va;
@@ -173,7 +173,7 @@ void btDeformableContactProjection::setConstraints()
{
continue;
}
btDeformableFaceRigidContactConstraint constraint(contact);
btDeformableFaceRigidContactConstraint constraint(contact, infoGlobal);
btVector3 va = constraint.getVa();
btVector3 vb = constraint.getVb();
const btVector3 vr = vb - va;
@@ -190,7 +190,7 @@ void btDeformableContactProjection::setConstraints()
{
const btSoftBody::DeformableFaceNodeContact& contact = psb->m_faceNodeContacts[j];
btDeformableFaceNodeContactConstraint constraint(contact);
btDeformableFaceNodeContactConstraint constraint(contact, infoGlobal);
btVector3 va = constraint.getVa();
btVector3 vb = constraint.getVb();
const btVector3 vr = vb - va;

2
src/BulletSoftBody/btDeformableContactProjection.h
View File

@@ -78,7 +78,7 @@ public:
virtual btScalar solveSplitImpulse(const btContactSolverInfo& infoGlobal);
// Add constraints to m_constraints. In addition, the constraints that each vertex own are recorded in m_constraintsDict.
virtual void setConstraints();
virtual void setConstraints(const btContactSolverInfo& infoGlobal);
// Set up projections for each vertex by adding the projection direction to
virtual void setProjection();

2
src/BulletSoftBody/btDeformableMultiBodyDynamicsWorld.cpp
View File

@@ -280,7 +280,7 @@ void btDeformableMultiBodyDynamicsWorld::solveConstraints(btScalar timeStep)
void btDeformableMultiBodyDynamicsWorld::setupConstraints()
{
// set up constraints between multibody and deformable bodies
m_deformableBodySolver->setConstraints();
m_deformableBodySolver->setConstraints(m_solverInfo);
// set up constraints among multibodies
{

1
src/BulletSoftBody/btSoftBodyInternals.h
View File

@@ -1182,6 +1182,7 @@ struct btSoftColliders
c.m_face = &f;
// friction is handled by the nodes to prevent sticking
const btScalar fc = 0;
// const btScalar fc = psb->m_cfg.kDF * m_colObj1Wrap->getCollisionObject()->getFriction();
// the effective inverse mass of the face as in https://graphics.stanford.edu/papers/cloth-sig02/cloth.pdf
ima = bary.getX()*c.m_weights.getX() * n0->m_im + bary.getY()*c.m_weights.getY() * n1->m_im + bary.getZ()*c.m_weights.getZ() * n2->m_im;