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treat the feature with the deepest penetration as static in deformable contact

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This commit is contained in:
Xuchen Han
2020-04-15 14:48:53 -07:00
parent ebc84b3b8d
commit 5cb252dc4c
5 changed files with 23 additions and 27 deletions
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2
src/BulletSoftBody/btDeformableBodySolver.cpp
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@@ -431,7 +431,7 @@ void btDeformableBodySolver::predictDeformableMotion(btSoftBody* psb, btScalar d
n.m_v *= max_v;
}
n.m_q = n.m_x + n.m_v * dt;
n.m_constrained = false;
n.m_penetration = 0;
}
/* Nodes */

18
src/BulletSoftBody/btDeformableContactProjection.cpp
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@@ -224,7 +224,7 @@ void btDeformableContactProjection::setProjection()
for (int j = 0; j < m_staticConstraints[i].size(); ++j)
{
int index = m_staticConstraints[i][j].m_node->index;
m_staticConstraints[i][j].m_node->m_constrained = true;
m_staticConstraints[i][j].m_node->m_penetration = SIMD_INFINITY;
btAlignedObjectArray<int> indices;
btAlignedObjectArray<btVector3> vecs1,vecs2,vecs3;
indices.push_back(index);
@@ -239,7 +239,7 @@ void btDeformableContactProjection::setProjection()
for (int j = 0; j < m_nodeAnchorConstraints[i].size(); ++j)
{
int index = m_nodeAnchorConstraints[i][j].m_anchor->m_node->index;
m_nodeAnchorConstraints[i][j].m_anchor->m_node->m_constrained = true;
m_nodeAnchorConstraints[i][j].m_anchor->m_node->m_penetration = SIMD_INFINITY;
btAlignedObjectArray<int> indices;
btAlignedObjectArray<btVector3> vecs1,vecs2,vecs3;
indices.push_back(index);
@@ -253,7 +253,7 @@ void btDeformableContactProjection::setProjection()
for (int j = 0; j < m_nodeRigidConstraints[i].size(); ++j)
{
int index = m_nodeRigidConstraints[i][j].m_node->index;
m_nodeRigidConstraints[i][j].m_node->m_constrained = true;
m_nodeRigidConstraints[i][j].m_node->m_penetration = -m_nodeRigidConstraints[i][j].getContact()->m_cti.m_offset;
btAlignedObjectArray<int> indices;
indices.push_back(index);
btAlignedObjectArray<btVector3> vecs1,vecs2,vecs3;
@@ -276,11 +276,12 @@ void btDeformableContactProjection::setProjection()
{
const btSoftBody::Face* face = m_faceRigidConstraints[i][j].m_face;
btVector3 bary = m_faceRigidConstraints[i][j].getContact()->m_bary;
btScalar penetration = -m_faceRigidConstraints[i][j].getContact()->m_cti.m_offset;
if (m_faceRigidConstraints[i][j].m_static)
{
for (int l = 0; l < 3; ++l)
{
face->m_n[l]->m_constrained = true;
face->m_n[l]->m_penetration = penetration;
btReducedVector rv(dof);
for (int k = 0; k < 3; ++k)
{
@@ -340,7 +341,7 @@ void btDeformableContactProjection::setLagrangeMultiplier()
for (int j = 0; j < m_staticConstraints[i].size(); ++j)
{
int index = m_staticConstraints[i][j].m_node->index;
m_staticConstraints[i][j].m_node->m_constrained = true;
m_staticConstraints[i][j].m_node->m_penetration = SIMD_INFINITY;
LagrangeMultiplier lm;
lm.m_num_nodes = 1;
lm.m_indices[0] = index;
@@ -354,7 +355,7 @@ void btDeformableContactProjection::setLagrangeMultiplier()
for (int j = 0; j < m_nodeAnchorConstraints[i].size(); ++j)
{
int index = m_nodeAnchorConstraints[i][j].m_anchor->m_node->index;
m_nodeAnchorConstraints[i][j].m_anchor->m_node->m_constrained = true;
m_nodeAnchorConstraints[i][j].m_anchor->m_node->m_penetration = SIMD_INFINITY;
LagrangeMultiplier lm;
lm.m_num_nodes = 1;
lm.m_indices[0] = index;
@@ -368,7 +369,7 @@ void btDeformableContactProjection::setLagrangeMultiplier()
for (int j = 0; j < m_nodeRigidConstraints[i].size(); ++j)
{
int index = m_nodeRigidConstraints[i][j].m_node->index;
m_nodeRigidConstraints[i][j].m_node->m_constrained = true;
m_nodeRigidConstraints[i][j].m_node->m_penetration = -m_nodeRigidConstraints[i][j].getContact()->m_cti.m_offset;
LagrangeMultiplier lm;
lm.m_num_nodes = 1;
lm.m_indices[0] = index;
@@ -392,11 +393,12 @@ void btDeformableContactProjection::setLagrangeMultiplier()
const btSoftBody::Face* face = m_faceRigidConstraints[i][j].m_face;
btVector3 bary = m_faceRigidConstraints[i][j].getContact()->m_bary;
btScalar penetration = -m_faceRigidConstraints[i][j].getContact()->m_cti.m_offset;
LagrangeMultiplier lm;
lm.m_num_nodes = 3;
for (int k = 0; k<3; ++k)
{
face->m_n[k]->m_constrained = true;
face->m_n[k]->m_penetration = penetration;
lm.m_indices[k] = face->m_n[k]->index;
lm.m_weights[k] = bary[k];
}

5
src/BulletSoftBody/btDeformableMultiBodyDynamicsWorld.cpp
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@@ -261,10 +261,7 @@ void btDeformableMultiBodyDynamicsWorld::performGeometricCollisions(btScalar tim
{
for (int j = 0; j < psb->m_nodes.size(); ++j)
{
if (!psb->m_nodes[j].m_constrained)
{
psb->m_nodes[j].m_v *= psb->m_dampingCoefficient;
}
psb->m_nodes[j].m_v *= psb->m_dampingCoefficient;
}
}
}

22
src/BulletSoftBody/btSoftBody.h
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@@ -268,7 +268,7 @@ public:
btScalar m_im; // 1/mass
btScalar m_area; // Area
btDbvtNode* m_leaf; // Leaf data
bool m_constrained; // constrained node
btScalar m_penetration; // depth of penetration
int m_battach : 1; // Attached
int index;
};
@@ -1303,20 +1303,20 @@ public:
I = -btMin(repulsionStiffness * timeStep * d, mass * (OVERLAP_REDUCTION_FACTOR * d / timeStep - vn));
if (vn < 0)
I += 0.5 * mass * vn;
bool face_constrained = false, node_constrained = node->m_constrained;
btScalar face_penetration = 0, node_penetration = node->m_penetration;
for (int i = 0; i < 3; ++i)
face_constrained |= face->m_n[i]->m_constrained;
face_penetration = btMax(face_penetration, face->m_n[i]->m_penetration);
btScalar I_tilde = .5 *I /(1.0+w.length2());
// double the impulse if node or face is constrained.
if (face_constrained || node_constrained)
I_tilde *= 2.0;
if (!face_constrained)
// if (face_penetration > 0 || node_penetration > 0)
// I_tilde *= 2.0;
if (face_penetration <= node_penetration)
{
for (int j = 0; j < 3; ++j)
face->m_n[j]->m_v += w[j]*n*I_tilde*node->m_im;
}
if (!node_constrained)
if (face_penetration >= node_penetration)
{
node->m_v -= I_tilde*node->m_im*n;
}
@@ -1332,14 +1332,14 @@ public:
vt.safeNormalize();
I_tilde = .5 *I /(1.0+w.length2());
// double the impulse if node or face is constrained.
if (face_constrained || node_constrained)
I_tilde *= 2.0;
if (!face_constrained)
// if (face_penetration > 0 || node_penetration > 0)
// I_tilde *= 2.0;
if (face_penetration <= node_penetration)
{
for (int j = 0; j < 3; ++j)
face->m_n[j]->m_v += w[j] * vt * I_tilde * (face->m_n[j])->m_im;
}
if (!node_constrained)
if (face_penetration >= node_penetration)
{
node->m_v -= I_tilde * node->m_im * vt;
}

3
src/BulletSoftBody/btSoftBodyInternals.h
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@@ -1664,7 +1664,6 @@ struct btSoftColliders
const btScalar ms = ima + imb;
if (ms > 0)
{
n.m_constrained = true;
// resolve contact at x_n
psb->checkDeformableContact(m_colObj1Wrap, n.m_x, m, c.m_cti, /*predict = */ false);
btSoftBody::sCti& cti = c.m_cti;
@@ -1745,8 +1744,6 @@ struct btSoftColliders
btSoftBody::Node* n0 = f.m_n[0];
btSoftBody::Node* n1 = f.m_n[1];
btSoftBody::Node* n2 = f.m_n[2];
if (n0->m_constrained && n1->m_constrained && n2->m_constrained)
return;
const btScalar m = (n0->m_im > 0 && n1->m_im > 0 && n2->m_im > 0 )? dynmargin : stamargin;
btSoftBody::DeformableFaceRigidContact c;
btVector3 contact_point;