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

add elastic and damping stiffness of spring into the force class

Browse Source
This commit is contained in:
Xuchen Han
2019-08-15 17:47:28 -07:00
parent df7f216bf8
commit aa4d5bda3e
1 changed files with 9 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
src/BulletSoftBody/btDeformableMassSpringForce.h
View File

@@ -19,9 +19,13 @@
class btDeformableMassSpringForce : public btDeformableLagrangianForce class btDeformableMassSpringForce : public btDeformableLagrangianForce
{ {
bool m_momentum_conserving; bool m_momentum_conserving;
btScalar m_elasticStiffness, m_dampingStiffness;
public: public:
typedef btAlignedObjectArray<btVector3> TVStack; typedef btAlignedObjectArray<btVector3> TVStack;
btDeformableMassSpringForce() : m_momentum_conserving(false) btDeformableMassSpringForce() : m_momentum_conserving(false), m_elasticStiffness(1), m_dampingStiffness(0.05)
{
}
btDeformableMassSpringForce(btScalar k, btScalar d, bool conserve_angular = false) : m_momentum_conserving(conserve_angular), m_elasticStiffness(k), m_dampingStiffness(d)
{ {
} }
@@ -52,14 +56,13 @@ public:
// damping force // damping force
btVector3 v_diff = (node2->m_v - node1->m_v); btVector3 v_diff = (node2->m_v - node1->m_v);
btScalar k_damp = psb->m_dampingCoefficient; btVector3 scaled_force = scale * m_dampingStiffness * v_diff;
btVector3 scaled_force = scale * k_damp * v_diff;
if (m_momentum_conserving) if (m_momentum_conserving)
{ {
if ((node2->m_q - node1->m_q).norm() > SIMD_EPSILON) if ((node2->m_q - node1->m_q).norm() > SIMD_EPSILON)
{ {
btVector3 dir = (node2->m_q - node1->m_q).normalized(); btVector3 dir = (node2->m_q - node1->m_q).normalized();
scaled_force = scale * k_damp * v_diff.dot(dir) * dir; scaled_force = scale * m_dampingStiffness * v_diff.dot(dir) * dir;
} }
} }
force[id1] += scaled_force; force[id1] += scaled_force;
@@ -80,7 +83,6 @@ public:
const btSoftBody::Link& link = psb->m_links[j]; const btSoftBody::Link& link = psb->m_links[j];
btSoftBody::Node* node1 = link.m_n[0]; btSoftBody::Node* node1 = link.m_n[0];
btSoftBody::Node* node2 = link.m_n[1]; btSoftBody::Node* node2 = link.m_n[1];
btScalar kLST = link.Feature::m_material->m_kLST;
btScalar r = link.m_rl; btScalar r = link.m_rl;
size_t id1 = node1->index; size_t id1 = node1->index;
size_t id2 = node2->index; size_t id2 = node2->index;
@@ -89,7 +91,7 @@ public:
// explicit elastic force // explicit elastic force
btVector3 dir = (node2->m_q - node1->m_q); btVector3 dir = (node2->m_q - node1->m_q);
btVector3 dir_normalized = dir.normalized(); btVector3 dir_normalized = dir.normalized();
btVector3 scaled_force = scale * kLST * (dir - dir_normalized * r); btVector3 scaled_force = scale * m_elasticStiffness * (dir - dir_normalized * r);
force[id1] += scaled_force; force[id1] += scaled_force;
force[id2] -= scaled_force; force[id2] -= scaled_force;
} }
@@ -102,7 +104,7 @@ public:
for (int i = 0; i < m_softBodies.size(); ++i) for (int i = 0; i < m_softBodies.size(); ++i)
{ {
const btSoftBody* psb = m_softBodies[i]; const btSoftBody* psb = m_softBodies[i];
btScalar scaled_k_damp = psb->m_dampingCoefficient * scale; btScalar scaled_k_damp = m_dampingStiffness * scale;
for (int j = 0; j < psb->m_links.size(); ++j) for (int j = 0; j < psb->m_links.size(); ++j)
{ {
const btSoftBody::Link& link = psb->m_links[j]; const btSoftBody::Link& link = psb->m_links[j];