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add damping energy to mass spring

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This commit is contained in:
Xuchen Han
2019-09-18 16:06:09 -07:00
parent d761b2cd68
commit cca220eb27
5 changed files with 50 additions and 18 deletions
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2
src/BulletSoftBody/btDeformableBackwardEulerObjective.h
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@@ -93,6 +93,7 @@ public:
m_preconditioner->operator()(x,b);
}
// reindex all the vertices
virtual void updateId()
{
size_t node_id = 0;
@@ -125,6 +126,7 @@ public:
m_implicit = implicit;
}
// Calculate the total potential energy in the system
btScalar totalEnergy(btScalar dt);
};

38
src/BulletSoftBody/btDeformableMassSpringForce.h
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@@ -62,9 +62,9 @@ public:
btVector3 scaled_force = scale * m_dampingStiffness * v_diff;
if (m_momentum_conserving)
{
if ((node2->m_q - node1->m_q).norm() > SIMD_EPSILON)
if ((node2->m_x - node1->m_x).norm() > SIMD_EPSILON)
{
btVector3 dir = (node2->m_q - node1->m_q).normalized();
btVector3 dir = (node2->m_x - node1->m_x).normalized();
scaled_force = scale * m_dampingStiffness * v_diff.dot(dir) * dir;
}
}
@@ -118,9 +118,9 @@ public:
btVector3 local_scaled_df = scaled_k_damp * (dv[id2] - dv[id1]);
if (m_momentum_conserving)
{
if ((node2->m_q - node1->m_q).norm() > SIMD_EPSILON)
if ((node2->m_x - node1->m_x).norm() > SIMD_EPSILON)
{
btVector3 dir = (node2->m_q - node1->m_q).normalized();
btVector3 dir = (node2->m_x - node1->m_x).normalized();
local_scaled_df= scaled_k_damp * (dv[id2] - dv[id1]).dot(dir) * dir;
}
}
@@ -129,6 +129,7 @@ public:
}
}
}
virtual double totalElasticEnergy(btScalar dt)
{
double energy = 0;
@@ -150,6 +151,35 @@ public:
return energy;
}
virtual double totalDampingEnergy(btScalar dt)
{
double energy = 0;
int sz = 0;
for (int i = 0; i < m_softBodies.size(); ++i)
{
btSoftBody* psb = m_softBodies[i];
for (int j = 0; j < psb->m_nodes.size(); ++j)
{
sz = btMax(sz, psb->m_nodes[j].index);
}
}
TVStack dampingForce;
dampingForce.resize(sz+1);
for (int i = 0; i < dampingForce.size(); ++i)
dampingForce[i].setZero();
addScaledDampingForce(0.5, dampingForce);
for (int i = 0; i < m_softBodies.size(); ++i)
{
btSoftBody* psb = m_softBodies[i];
for (int j = 0; j < psb->m_nodes.size(); ++j)
{
const btSoftBody::Node& node = psb->m_nodes[j];
energy -= dampingForce[node.index].dot(node.m_v) / dt;
}
}
return energy;
}
virtual void addScaledElasticForceDifferential(btScalar scale, const TVStack& dx, TVStack& df)
{
// implicit damping force differential