mirror of
https://github.com/bulletphysics/bullet3.git
synced 2026-10-23 09:10:59 +00:00
479 lines
22 KiB
C++
479 lines
22 KiB
C++
/*
|
|
Bullet Continuous Collision Detection and Physics Library
|
|
Copyright (c) 2016 Google Inc. http://bulletphysics.org
|
|
This software is provided 'as-is', without any express or implied warranty.
|
|
In no event will the authors be held liable for any damages arising from the use of this software.
|
|
Permission is granted to anyone to use this software for any purpose,
|
|
including commercial applications, and to alter it and redistribute it freely,
|
|
subject to the following restrictions:
|
|
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.
|
|
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
|
|
3. This notice may not be removed or altered from any source distribution.
|
|
*/
|
|
|
|
#include "btDeformableContactProjection.h"
|
|
#include "btDeformableRigidDynamicsWorld.h"
|
|
#include <algorithm>
|
|
#include <cmath>
|
|
static void findJacobian(const btMultiBodyLinkCollider* multibodyLinkCol,
|
|
btMultiBodyJacobianData& jacobianData,
|
|
const btVector3& contact_point,
|
|
const btVector3& dir)
|
|
{
|
|
const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
|
|
jacobianData.m_jacobians.resize(ndof);
|
|
jacobianData.m_deltaVelocitiesUnitImpulse.resize(ndof);
|
|
btScalar* jac = &jacobianData.m_jacobians[0];
|
|
|
|
multibodyLinkCol->m_multiBody->fillContactJacobianMultiDof(multibodyLinkCol->m_link, contact_point, dir, jac, jacobianData.scratch_r, jacobianData.scratch_v, jacobianData.scratch_m);
|
|
multibodyLinkCol->m_multiBody->calcAccelerationDeltasMultiDof(&jacobianData.m_jacobians[0], &jacobianData.m_deltaVelocitiesUnitImpulse[0], jacobianData.scratch_r, jacobianData.scratch_v);
|
|
}
|
|
|
|
static btVector3 generateUnitOrthogonalVector(const btVector3& u)
|
|
{
|
|
btScalar ux = u.getX();
|
|
btScalar uy = u.getY();
|
|
btScalar uz = u.getZ();
|
|
btScalar ax = std::abs(ux);
|
|
btScalar ay = std::abs(uy);
|
|
btScalar az = std::abs(uz);
|
|
btVector3 v;
|
|
if (ax <= ay && ax <= az)
|
|
v = btVector3(0, -uz, uy);
|
|
else if (ay <= ax && ay <= az)
|
|
v = btVector3(-uz, 0, ux);
|
|
else
|
|
v = btVector3(-uy, ux, 0);
|
|
v.normalize();
|
|
return v;
|
|
}
|
|
|
|
void btDeformableContactProjection::update()
|
|
{
|
|
///solve rigid body constraints
|
|
m_world->getSolverInfo().m_numIterations = 1;
|
|
m_world->btMultiBodyDynamicsWorld::solveInternalConstraints(m_world->getSolverInfo());
|
|
|
|
// loop through constraints to set constrained values
|
|
for (int index = 0; index < m_constraints.size(); ++index)
|
|
{
|
|
btAlignedObjectArray<DeformableFrictionConstraint>& frictions = *m_frictions[m_constraints.getKeyAtIndex(index)];
|
|
btAlignedObjectArray<DeformableContactConstraint>& constraints = *m_constraints.getAtIndex(index);
|
|
for (int i = 0; i < constraints.size(); ++i)
|
|
{
|
|
DeformableContactConstraint& constraint = constraints[i];
|
|
DeformableFrictionConstraint& friction = frictions[i];
|
|
for (int j = 0; j < constraint.m_contact.size(); ++j)
|
|
{
|
|
if (constraint.m_contact[j] == NULL)
|
|
{
|
|
// nothing needs to be done for dirichelet constraints
|
|
continue;
|
|
}
|
|
const btSoftBody::RContact* c = constraint.m_contact[j];
|
|
const btSoftBody::sCti& cti = c->m_cti;
|
|
|
|
if (cti.m_colObj->hasContactResponse())
|
|
{
|
|
btVector3 va(0, 0, 0);
|
|
btRigidBody* rigidCol = 0;
|
|
btMultiBodyLinkCollider* multibodyLinkCol = 0;
|
|
const btScalar* deltaV_normal;
|
|
|
|
// 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(c->m_c1)) * m_dt : 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 = &c->jacobianData_normal.m_jacobians[0];
|
|
const btScalar* J_t1 = &c->jacobianData_t1.m_jacobians[0];
|
|
const btScalar* J_t2 = &c->jacobianData_t2.m_jacobians[0];
|
|
const btScalar* local_v = multibodyLinkCol->m_multiBody->getVelocityVector();
|
|
deltaV_normal = &c->jacobianData_normal.m_deltaVelocitiesUnitImpulse[0];
|
|
// add in the normal component of the va
|
|
btScalar vel = 0.0;
|
|
for (int k = 0; k < ndof; ++k)
|
|
{
|
|
vel += local_v[k] * J_n[k];
|
|
}
|
|
va = cti.m_normal * vel * m_dt;
|
|
|
|
// add in the tangential components of the va
|
|
vel = 0.0;
|
|
for (int k = 0; k < ndof; ++k)
|
|
{
|
|
vel += local_v[k] * J_t1[k];
|
|
}
|
|
va += c->t1 * vel * m_dt;
|
|
vel = 0.0;
|
|
for (int k = 0; k < ndof; ++k)
|
|
{
|
|
vel += local_v[k] * J_t2[k];
|
|
}
|
|
va += c->t2 * vel * m_dt;
|
|
}
|
|
}
|
|
|
|
const btVector3 vb = c->m_node->m_v * m_dt;
|
|
const btVector3 vr = vb - va;
|
|
const btScalar dn = btDot(vr, cti.m_normal);
|
|
btVector3 impulse = c->m_c0 * vr;
|
|
const btVector3 impulse_normal = c->m_c0 * (cti.m_normal * dn);
|
|
const btVector3 impulse_tangent = impulse - impulse_normal;
|
|
|
|
// start friction handling
|
|
// copy old data
|
|
friction.m_impulse_prev[j] = friction.m_impulse[j];
|
|
friction.m_dv_prev[j] = friction.m_dv[j];
|
|
friction.m_static_prev[j] = friction.m_static[j];
|
|
|
|
// get the current tangent direction
|
|
btScalar local_tangent_norm = impulse_tangent.norm();
|
|
btVector3 local_tangent_dir = btVector3(0,0,0);
|
|
if (local_tangent_norm > SIMD_EPSILON)
|
|
local_tangent_dir = impulse_tangent.normalized();
|
|
|
|
// accumulated impulse on the rb in this and all prev cg iterations
|
|
constraint.m_accumulated_normal_impulse[j] += impulse_normal.dot(cti.m_normal);
|
|
const btScalar& accumulated_normal = constraint.m_accumulated_normal_impulse[j];
|
|
|
|
// the total tangential impulse required to stop sliding
|
|
btVector3 tangent = friction.m_accumulated_tangent_impulse[j] + impulse_tangent;
|
|
btScalar tangent_norm = tangent.norm();
|
|
|
|
if (accumulated_normal < 0)
|
|
{
|
|
friction.m_direction[j] = -local_tangent_dir;
|
|
// do not allow switching from static friction to dynamic friction
|
|
// it causes cg to explode
|
|
if (-accumulated_normal*c->m_c3 < tangent_norm && friction.m_static_prev[j] == false && friction.m_released[j] == false)
|
|
{
|
|
friction.m_static[j] = false;
|
|
friction.m_impulse[j] = -accumulated_normal*c->m_c3;
|
|
}
|
|
else
|
|
{
|
|
friction.m_static[j] = true;
|
|
friction.m_impulse[j] = tangent_norm;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
friction.m_released[j] = true;
|
|
friction.m_static[j] = false;
|
|
friction.m_impulse[j] = 0;
|
|
friction.m_direction[j] = btVector3(0,0,0);
|
|
}
|
|
friction.m_dv[j] = friction.m_impulse[j] * c->m_c2/m_dt;
|
|
friction.m_accumulated_tangent_impulse[j] = -friction.m_impulse[j] * friction.m_direction[j];
|
|
|
|
// the incremental impulse applied to rb in the tangential direction
|
|
btVector3 incremental_tangent = (friction.m_impulse_prev[j] * friction.m_direction_prev[j])-(friction.m_impulse[j] * friction.m_direction[j]);
|
|
|
|
|
|
// dv = new_impulse + accumulated velocity change in previous CG iterations
|
|
// so we have the invariant node->m_v = backupVelocity + dv;
|
|
|
|
btScalar dvn = -accumulated_normal * c->m_c2/m_dt;
|
|
|
|
// the following is equivalent
|
|
/*
|
|
btVector3 dv = -impulse_normal * c->m_c2/m_dt + c->m_node->m_v - backupVelocity[m_indices->at(c->m_node)];
|
|
btScalar dvn = dv.dot(cti.m_normal);
|
|
*/
|
|
|
|
constraint.m_value[j] = dvn;
|
|
|
|
// the incremental impulse:
|
|
// in the normal direction it's the normal component of "impulse"
|
|
// in the tangent direction it's the difference between the frictional impulse in the iteration and the previous iteration
|
|
impulse = impulse_normal + incremental_tangent;
|
|
if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
|
|
{
|
|
if (rigidCol)
|
|
rigidCol->applyImpulse(impulse, c->m_c1);
|
|
}
|
|
else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
|
|
{
|
|
if (multibodyLinkCol)
|
|
{
|
|
// apply normal component of the impulse
|
|
multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof(deltaV_normal, impulse.dot(cti.m_normal));
|
|
if (incremental_tangent.norm() > SIMD_EPSILON)
|
|
{
|
|
// apply tangential component of the impulse
|
|
const btScalar* deltaV_t1 = &c->jacobianData_t1.m_deltaVelocitiesUnitImpulse[0];
|
|
multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof(deltaV_t1, impulse.dot(c->t1));
|
|
const btScalar* deltaV_t2 = &c->jacobianData_t2.m_deltaVelocitiesUnitImpulse[0];
|
|
multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof(deltaV_t2, impulse.dot(c->t2));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void btDeformableContactProjection::setConstraints()
|
|
{
|
|
BT_PROFILE("setConstraints");
|
|
// set Dirichlet constraint
|
|
for (int i = 0; i < m_softBodies.size(); ++i)
|
|
{
|
|
btSoftBody* psb = m_softBodies[i];
|
|
for (int j = 0; j < psb->m_nodes.size(); ++j)
|
|
{
|
|
if (psb->m_nodes[j].m_im == 0)
|
|
{
|
|
btAlignedObjectArray<DeformableContactConstraint> c;
|
|
c.reserve(3);
|
|
c.push_back(DeformableContactConstraint(btVector3(1,0,0)));
|
|
c.push_back(DeformableContactConstraint(btVector3(0,1,0)));
|
|
c.push_back(DeformableContactConstraint(btVector3(0,0,1)));
|
|
m_constraints.insert(psb->m_nodes[j].index, c);
|
|
|
|
btAlignedObjectArray<DeformableFrictionConstraint> f;
|
|
f.reserve(3);
|
|
f.push_back(DeformableFrictionConstraint());
|
|
f.push_back(DeformableFrictionConstraint());
|
|
f.push_back(DeformableFrictionConstraint());
|
|
m_frictions.insert(psb->m_nodes[j].index, f);
|
|
}
|
|
}
|
|
}
|
|
for (int i = 0; i < m_softBodies.size(); ++i)
|
|
{
|
|
btSoftBody* psb = m_softBodies[i];
|
|
btMultiBodyJacobianData jacobianData_normal;
|
|
btMultiBodyJacobianData jacobianData_complementary;
|
|
for (int j = 0; j < psb->m_rcontacts.size(); ++j)
|
|
{
|
|
const btSoftBody::RContact& c = psb->m_rcontacts[j];
|
|
// skip anchor points
|
|
if (c.m_node->m_im == 0)
|
|
{
|
|
continue;
|
|
}
|
|
|
|
const btSoftBody::sCti& cti = c.m_cti;
|
|
if (cti.m_colObj->hasContactResponse())
|
|
{
|
|
btVector3 va(0, 0, 0);
|
|
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(c.m_c1)) * m_dt : btVector3(0, 0, 0);
|
|
}
|
|
else if (cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
|
|
{
|
|
multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(cti.m_colObj);
|
|
if (multibodyLinkCol)
|
|
{
|
|
btScalar vel = 0.0;
|
|
const btScalar* jac = &c.jacobianData_normal.m_jacobians[0];
|
|
const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
|
|
for (int j = 0; j < ndof; ++j)
|
|
{
|
|
vel += multibodyLinkCol->m_multiBody->getVelocityVector()[j] * jac[j];
|
|
}
|
|
va = cti.m_normal * vel * m_dt;
|
|
}
|
|
}
|
|
|
|
const btVector3 vb = c.m_node->m_v * m_dt;
|
|
const btVector3 vr = vb - va;
|
|
const btScalar dn = btDot(vr, cti.m_normal);
|
|
if (dn < SIMD_EPSILON)
|
|
{
|
|
|
|
if (m_constraints.find(c.m_node->index) == NULL)
|
|
{
|
|
btAlignedObjectArray<DeformableContactConstraint> constraints;
|
|
constraints.push_back(DeformableContactConstraint(c));
|
|
m_constraints.insert(c.m_node->index,constraints);
|
|
btAlignedObjectArray<DeformableFrictionConstraint> frictions;
|
|
frictions.push_back(DeformableFrictionConstraint());
|
|
m_frictions.insert(c.m_node->index,frictions);
|
|
}
|
|
else
|
|
{
|
|
// group colinear constraints into one
|
|
const btScalar angle_epsilon = 0.015192247; // less than 10 degree
|
|
bool merged = false;
|
|
btAlignedObjectArray<DeformableContactConstraint>& constraints = *m_constraints[c.m_node->index];
|
|
btAlignedObjectArray<DeformableFrictionConstraint>& frictions = *m_frictions[c.m_node->index];
|
|
for (int j = 0; j < constraints.size(); ++j)
|
|
{
|
|
const btAlignedObjectArray<btVector3>& dirs = constraints[j].m_direction;
|
|
btScalar dot_prod = dirs[0].dot(cti.m_normal);
|
|
if (std::abs(std::abs(dot_prod) - 1) < angle_epsilon)
|
|
{
|
|
// group the constraints
|
|
constraints[j].append(c);
|
|
// push in an empty friction
|
|
frictions[j].append();
|
|
merged = true;
|
|
break;
|
|
}
|
|
}
|
|
const int dim = 3;
|
|
// hard coded no more than 3 constraint directions
|
|
if (!merged && constraints.size() < dim)
|
|
{
|
|
constraints.push_back(DeformableContactConstraint(c));
|
|
frictions.push_back(DeformableFrictionConstraint());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void btDeformableContactProjection::enforceConstraint(TVStack& x)
|
|
{
|
|
const int dim = 3;
|
|
for (int index = 0; index < m_constraints.size(); ++index)
|
|
{
|
|
const btAlignedObjectArray<DeformableContactConstraint>& constraints = *m_constraints.getAtIndex(index);
|
|
size_t i = m_constraints.getKeyAtIndex(index).getUid1();
|
|
const btAlignedObjectArray<DeformableFrictionConstraint>& frictions = *m_frictions[m_constraints.getKeyAtIndex(index)];
|
|
btAssert(constraints.size() <= dim);
|
|
btAssert(constraints.size() > 0);
|
|
if (constraints.size() == 1)
|
|
{
|
|
x[i] -= x[i].dot(constraints[0].m_direction[0]) * constraints[0].m_direction[0];
|
|
for (int j = 0; j < constraints[0].m_direction.size(); ++j)
|
|
x[i] += constraints[0].m_value[j] * constraints[0].m_direction[j];
|
|
}
|
|
else if (constraints.size() == 2)
|
|
{
|
|
btVector3 free_dir = btCross(constraints[0].m_direction[0], constraints[1].m_direction[0]);
|
|
btAssert(free_dir.norm() > SIMD_EPSILON)
|
|
free_dir.normalize();
|
|
x[i] = x[i].dot(free_dir) * free_dir;
|
|
for (int j = 0; j < constraints.size(); ++j)
|
|
{
|
|
for (int k = 0; k < constraints[j].m_direction.size(); ++k)
|
|
{
|
|
x[i] += constraints[j].m_value[k] * constraints[j].m_direction[k];
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
x[i].setZero();
|
|
for (int j = 0; j < constraints.size(); ++j)
|
|
{
|
|
for (int k = 0; k < constraints[j].m_direction.size(); ++k)
|
|
{
|
|
x[i] += constraints[j].m_value[k] * constraints[j].m_direction[k];
|
|
}
|
|
}
|
|
}
|
|
|
|
// apply friction if the node is not constrained in all directions
|
|
if (constraints.size() < 3)
|
|
{
|
|
for (int f = 0; f < frictions.size(); ++f)
|
|
{
|
|
const DeformableFrictionConstraint& friction= frictions[f];
|
|
for (int j = 0; j < friction.m_direction.size(); ++j)
|
|
{
|
|
// add the friction constraint
|
|
if (friction.m_static[j] == true)
|
|
{
|
|
x[i] -= x[i].dot(friction.m_direction[j]) * friction.m_direction[j];
|
|
x[i] += friction.m_direction[j] * friction.m_dv[j];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void btDeformableContactProjection::project(TVStack& x)
|
|
{
|
|
const int dim = 3;
|
|
for (int index = 0; index < m_constraints.size(); ++index)
|
|
{
|
|
const btAlignedObjectArray<DeformableContactConstraint>& constraints = *m_constraints.getAtIndex(index);
|
|
size_t i = m_constraints.getKeyAtIndex(index).getUid1();
|
|
btAlignedObjectArray<DeformableFrictionConstraint>& frictions = *m_frictions[m_constraints.getKeyAtIndex(index)];
|
|
btAssert(constraints.size() <= dim);
|
|
btAssert(constraints.size() > 0);
|
|
if (constraints.size() == 1)
|
|
{
|
|
x[i] -= x[i].dot(constraints[0].m_direction[0]) * constraints[0].m_direction[0];
|
|
}
|
|
else if (constraints.size() == 2)
|
|
{
|
|
btVector3 free_dir = btCross(constraints[0].m_direction[0], constraints[1].m_direction[0]);
|
|
btAssert(free_dir.norm() > SIMD_EPSILON)
|
|
free_dir.normalize();
|
|
x[i] = x[i].dot(free_dir) * free_dir;
|
|
}
|
|
else
|
|
x[i].setZero();
|
|
|
|
// apply friction if the node is not constrained in all directions
|
|
if (constraints.size() < 3)
|
|
{
|
|
bool has_static_constraint = false;
|
|
for (int f = 0; f < frictions.size(); ++f)
|
|
{
|
|
DeformableFrictionConstraint& friction= frictions[f];
|
|
for (int j = 0; j < friction.m_static.size(); ++j)
|
|
has_static_constraint = has_static_constraint || friction.m_static[j];
|
|
}
|
|
|
|
for (int f = 0; f < frictions.size(); ++f)
|
|
{
|
|
DeformableFrictionConstraint& friction= frictions[f];
|
|
for (int j = 0; j < friction.m_direction.size(); ++j)
|
|
{
|
|
// clear the old friction force
|
|
if (friction.m_static_prev[j] == false)
|
|
{
|
|
x[i] -= friction.m_direction_prev[j] * friction.m_impulse_prev[j];
|
|
}
|
|
|
|
// only add to the rhs if there is no static friction constraint on the node
|
|
if (friction.m_static[j] == false)
|
|
{
|
|
if (!has_static_constraint)
|
|
x[i] += friction.m_direction[j] * friction.m_impulse[j];
|
|
}
|
|
else
|
|
{
|
|
// otherwise clear the constraint in the friction direction
|
|
x[i] -= x[i].dot(friction.m_direction[j]) * friction.m_direction[j];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void btDeformableContactProjection::reinitialize(bool nodeUpdated)
|
|
{
|
|
btCGProjection::reinitialize(nodeUpdated);
|
|
m_constraints.clear();
|
|
m_frictions.clear();
|
|
}
|
|
|
|
|
|
|