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switch explicit elastic force

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This commit is contained in:
Xuchen Han
2019-07-17 15:58:55 -07:00
parent 2fc376e8f5
commit 7846dd38dd
13 changed files with 193 additions and 77 deletions
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34
src/BulletSoftBody/btContactProjection.cpp
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@@ -85,35 +85,41 @@ void btContactProjection::update(const TVStack& dv, const TVStack& backupVelocit
// start friction handling
// copy old data
friction.m_direction_prev[j] = friction.m_direction[j];
friction.m_value_prev[j] = friction.m_value[j];
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];
if (accumulated_normal < 0 && accumulated_tangent.norm() > SIMD_EPSILON)
{
btScalar compare1 = -accumulated_normal*c->m_c3;
btScalar compare2 = accumulated_tangent.norm();
// do not allow switching from static friction to dynamic friction
// it causes cg to explode
if (-accumulated_normal*c->m_c3 < accumulated_tangent.norm() && friction.m_static_prev[j] == false)
if (-accumulated_normal*c->m_c3 < accumulated_tangent.norm() && friction.m_static_prev[j] == false && friction.m_released[j] == false)
{
friction.m_static[j] = false;
friction.m_value[j] = -accumulated_normal*c->m_c3;
friction.m_impulse[j] = -accumulated_normal*c->m_c3;
friction.m_dv[j] = -accumulated_normal*c->m_c3 *c->m_c2/m_dt ;
}
else
{
friction.m_static[j] = true;
friction.m_value[j] = accumulated_tangent.norm();
friction.m_impulse[j] = accumulated_tangent.norm();
friction.m_dv[j] = accumulated_tangent.norm() * c->m_c2/m_dt;
}
const btVector3 tangent_dir = accumulated_tangent.normalized();
impulse_tangent = friction.m_value[j] * tangent_dir;
friction.m_direction[j] = -tangent_dir;
}
else
{
friction.m_released[j] = true;
friction.m_static[j] = false;
friction.m_value[j] = 0;
impulse_tangent.setZero();
friction.m_impulse[j] = 0;
friction.m_dv[j] = 0;
}
friction.m_accumulated_impulse[j] = accumulated_normal * cti.m_normal - friction.m_impulse[j] * friction.m_direction[j];
if (1) // in the same CG solve, the set of constraits doesn't change
// if (dn <= SIMD_EPSILON)
{
@@ -128,8 +134,8 @@ void btContactProjection::update(const TVStack& dv, const TVStack& backupVelocit
// 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 + (friction.m_value_prev[j] * friction.m_direction_prev[j]) - (friction.m_value[j] * friction.m_direction[j]);
impulse = impulse_normal + (friction.m_impulse_prev[j] * friction.m_direction_prev[j]) - (friction.m_impulse[j] * friction.m_direction[j]);
// impulse = impulse_normal;
if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
{
if (rigidCol)
@@ -172,7 +178,6 @@ void btContactProjection::setConstraintDirections()
f.push_back(Friction());
f.push_back(Friction());
m_frictions[&(psb->m_nodes[j])] = f;
// no friction constraints for dirichlet
}
}
}
@@ -262,11 +267,14 @@ void btContactProjection::setConstraintDirections()
// push in an empty friction
frictions[j].m_direction.push_back(btVector3(0,0,0));
frictions[j].m_direction_prev.push_back(btVector3(0,0,0));
frictions[j].m_value.push_back(0);
frictions[j].m_value_prev.push_back(0);
frictions[j].m_impulse.push_back(0);
frictions[j].m_impulse_prev.push_back(0);
frictions[j].m_dv.push_back(0);
frictions[j].m_dv_prev.push_back(0);
frictions[j].m_static.push_back(false);
frictions[j].m_static_prev.push_back(false);
frictions[j].m_accumulated_impulse.push_back(btVector3(0,0,0));
frictions[j].m_released.push_back(false);
merged = true;
break;
}