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diff --git a/thirdparty/bullet/BulletSoftBody/btDeformableMassSpringForce.h b/thirdparty/bullet/BulletSoftBody/btDeformableMassSpringForce.h
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-/*
- Written by Xuchen Han <xuchenhan2015@u.northwestern.edu>
-
- Bullet Continuous Collision Detection and Physics Library
- Copyright (c) 2019 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.
- */
-
-#ifndef BT_MASS_SPRING_H
-#define BT_MASS_SPRING_H
-
-#include "btDeformableLagrangianForce.h"
-
-class btDeformableMassSpringForce : public btDeformableLagrangianForce
-{
- // If true, the damping force will be in the direction of the spring
- // If false, the damping force will be in the direction of the velocity
- bool m_momentum_conserving;
- btScalar m_elasticStiffness, m_dampingStiffness, m_bendingStiffness;
-
-public:
- typedef btAlignedObjectArray<btVector3> TVStack;
- btDeformableMassSpringForce() : m_momentum_conserving(false), m_elasticStiffness(1), m_dampingStiffness(0.05)
- {
- }
- btDeformableMassSpringForce(btScalar k, btScalar d, bool conserve_angular = true, double bending_k = -1) : m_momentum_conserving(conserve_angular), m_elasticStiffness(k), m_dampingStiffness(d), m_bendingStiffness(bending_k)
- {
- if (m_bendingStiffness < btScalar(0))
- {
- m_bendingStiffness = m_elasticStiffness;
- }
- }
-
- virtual void addScaledForces(btScalar scale, TVStack& force)
- {
- addScaledDampingForce(scale, force);
- addScaledElasticForce(scale, force);
- }
-
- virtual void addScaledExplicitForce(btScalar scale, TVStack& force)
- {
- addScaledElasticForce(scale, force);
- }
-
- virtual void addScaledDampingForce(btScalar scale, TVStack& force)
- {
- int numNodes = getNumNodes();
- btAssert(numNodes <= force.size());
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- const btSoftBody* psb = m_softBodies[i];
- if (!psb->isActive())
- {
- continue;
- }
- for (int j = 0; j < psb->m_links.size(); ++j)
- {
- const btSoftBody::Link& link = psb->m_links[j];
- btSoftBody::Node* node1 = link.m_n[0];
- btSoftBody::Node* node2 = link.m_n[1];
- size_t id1 = node1->index;
- size_t id2 = node2->index;
-
- // damping force
- btVector3 v_diff = (node2->m_v - node1->m_v);
- btVector3 scaled_force = scale * m_dampingStiffness * v_diff;
- if (m_momentum_conserving)
- {
- if ((node2->m_x - node1->m_x).norm() > SIMD_EPSILON)
- {
- btVector3 dir = (node2->m_x - node1->m_x).normalized();
- scaled_force = scale * m_dampingStiffness * v_diff.dot(dir) * dir;
- }
- }
- force[id1] += scaled_force;
- force[id2] -= scaled_force;
- }
- }
- }
-
- virtual void addScaledElasticForce(btScalar scale, TVStack& force)
- {
- int numNodes = getNumNodes();
- btAssert(numNodes <= force.size());
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- const btSoftBody* psb = m_softBodies[i];
- if (!psb->isActive())
- {
- continue;
- }
- for (int j = 0; j < psb->m_links.size(); ++j)
- {
- const btSoftBody::Link& link = psb->m_links[j];
- btSoftBody::Node* node1 = link.m_n[0];
- btSoftBody::Node* node2 = link.m_n[1];
- btScalar r = link.m_rl;
- size_t id1 = node1->index;
- size_t id2 = node2->index;
-
- // elastic force
- btVector3 dir = (node2->m_q - node1->m_q);
- btVector3 dir_normalized = (dir.norm() > SIMD_EPSILON) ? dir.normalized() : btVector3(0, 0, 0);
- btScalar scaled_stiffness = scale * (link.m_bbending ? m_bendingStiffness : m_elasticStiffness);
- btVector3 scaled_force = scaled_stiffness * (dir - dir_normalized * r);
- force[id1] += scaled_force;
- force[id2] -= scaled_force;
- }
- }
- }
-
- virtual void addScaledDampingForceDifferential(btScalar scale, const TVStack& dv, TVStack& df)
- {
- // implicit damping force differential
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- btSoftBody* psb = m_softBodies[i];
- if (!psb->isActive())
- {
- continue;
- }
- btScalar scaled_k_damp = m_dampingStiffness * scale;
- for (int j = 0; j < psb->m_links.size(); ++j)
- {
- const btSoftBody::Link& link = psb->m_links[j];
- btSoftBody::Node* node1 = link.m_n[0];
- btSoftBody::Node* node2 = link.m_n[1];
- size_t id1 = node1->index;
- size_t id2 = node2->index;
-
- btVector3 local_scaled_df = scaled_k_damp * (dv[id2] - dv[id1]);
- if (m_momentum_conserving)
- {
- if ((node2->m_x - node1->m_x).norm() > SIMD_EPSILON)
- {
- btVector3 dir = (node2->m_x - node1->m_x).normalized();
- local_scaled_df = scaled_k_damp * (dv[id2] - dv[id1]).dot(dir) * dir;
- }
- }
- df[id1] += local_scaled_df;
- df[id2] -= local_scaled_df;
- }
- }
- }
-
- virtual void buildDampingForceDifferentialDiagonal(btScalar scale, TVStack& diagA)
- {
- // implicit damping force differential
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- btSoftBody* psb = m_softBodies[i];
- if (!psb->isActive())
- {
- continue;
- }
- btScalar scaled_k_damp = m_dampingStiffness * scale;
- for (int j = 0; j < psb->m_links.size(); ++j)
- {
- const btSoftBody::Link& link = psb->m_links[j];
- btSoftBody::Node* node1 = link.m_n[0];
- btSoftBody::Node* node2 = link.m_n[1];
- size_t id1 = node1->index;
- size_t id2 = node2->index;
- if (m_momentum_conserving)
- {
- if ((node2->m_x - node1->m_x).norm() > SIMD_EPSILON)
- {
- btVector3 dir = (node2->m_x - node1->m_x).normalized();
- for (int d = 0; d < 3; ++d)
- {
- if (node1->m_im > 0)
- diagA[id1][d] -= scaled_k_damp * dir[d] * dir[d];
- if (node2->m_im > 0)
- diagA[id2][d] -= scaled_k_damp * dir[d] * dir[d];
- }
- }
- }
- else
- {
- for (int d = 0; d < 3; ++d)
- {
- if (node1->m_im > 0)
- diagA[id1][d] -= scaled_k_damp;
- if (node2->m_im > 0)
- diagA[id2][d] -= scaled_k_damp;
- }
- }
- }
- }
- }
-
- virtual double totalElasticEnergy(btScalar dt)
- {
- double energy = 0;
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- const btSoftBody* psb = m_softBodies[i];
- if (!psb->isActive())
- {
- continue;
- }
- for (int j = 0; j < psb->m_links.size(); ++j)
- {
- const btSoftBody::Link& link = psb->m_links[j];
- btSoftBody::Node* node1 = link.m_n[0];
- btSoftBody::Node* node2 = link.m_n[1];
- btScalar r = link.m_rl;
-
- // elastic force
- btVector3 dir = (node2->m_q - node1->m_q);
- energy += 0.5 * m_elasticStiffness * (dir.norm() - r) * (dir.norm() - r);
- }
- }
- 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];
- if (!psb->isActive())
- {
- continue;
- }
- 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
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- const btSoftBody* psb = m_softBodies[i];
- if (!psb->isActive())
- {
- continue;
- }
- for (int j = 0; j < psb->m_links.size(); ++j)
- {
- const btSoftBody::Link& link = psb->m_links[j];
- btSoftBody::Node* node1 = link.m_n[0];
- btSoftBody::Node* node2 = link.m_n[1];
- size_t id1 = node1->index;
- size_t id2 = node2->index;
- btScalar r = link.m_rl;
-
- btVector3 dir = (node1->m_q - node2->m_q);
- btScalar dir_norm = dir.norm();
- btVector3 dir_normalized = (dir_norm > SIMD_EPSILON) ? dir.normalized() : btVector3(0, 0, 0);
- btVector3 dx_diff = dx[id1] - dx[id2];
- btVector3 scaled_df = btVector3(0, 0, 0);
- btScalar scaled_k = scale * (link.m_bbending ? m_bendingStiffness : m_elasticStiffness);
- if (dir_norm > SIMD_EPSILON)
- {
- scaled_df -= scaled_k * dir_normalized.dot(dx_diff) * dir_normalized;
- scaled_df += scaled_k * dir_normalized.dot(dx_diff) * ((dir_norm - r) / dir_norm) * dir_normalized;
- scaled_df -= scaled_k * ((dir_norm - r) / dir_norm) * dx_diff;
- }
-
- df[id1] += scaled_df;
- df[id2] -= scaled_df;
- }
- }
- }
-
- virtual btDeformableLagrangianForceType getForceType()
- {
- return BT_MASSSPRING_FORCE;
- }
-};
-
-#endif /* btMassSpring_h */
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