792 lines
24 KiB
C++
792 lines
24 KiB
C++
#include "btReducedDeformableBody.h"
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#include "../btSoftBodyInternals.h"
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#include "btReducedDeformableBodyHelpers.h"
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#include "LinearMath/btTransformUtil.h"
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#include <iostream>
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#include <fstream>
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btReducedDeformableBody::btReducedDeformableBody(btSoftBodyWorldInfo* worldInfo, int node_count, const btVector3* x, const btScalar* m)
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: btSoftBody(worldInfo, node_count, x, m), m_rigidOnly(false)
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{
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// reduced deformable
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m_reducedModel = true;
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m_nReduced = 0;
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m_nFull = 0;
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m_nodeIndexOffset = 0;
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m_transform_lock = false;
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m_ksScale = 1.0;
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m_rhoScale = 1.0;
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// rigid motion
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m_linearVelocity.setZero();
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m_angularVelocity.setZero();
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m_internalDeltaLinearVelocity.setZero();
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m_internalDeltaAngularVelocity.setZero();
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m_angularVelocityFromReduced.setZero();
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m_internalDeltaAngularVelocityFromReduced.setZero();
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m_angularFactor.setValue(1, 1, 1);
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m_linearFactor.setValue(1, 1, 1);
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// m_invInertiaLocal.setValue(1, 1, 1);
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m_invInertiaLocal.setIdentity();
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m_mass = 0.0;
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m_inverseMass = 0.0;
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m_linearDamping = 0;
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m_angularDamping = 0;
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// Rayleigh damping
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m_dampingAlpha = 0;
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m_dampingBeta = 0;
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m_rigidTransformWorld.setIdentity();
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}
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void btReducedDeformableBody::setReducedModes(int num_modes, int full_size)
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{
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m_nReduced = num_modes;
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m_nFull = full_size;
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m_reducedDofs.resize(m_nReduced, 0);
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m_reducedDofsBuffer.resize(m_nReduced, 0);
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m_reducedVelocity.resize(m_nReduced, 0);
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m_reducedVelocityBuffer.resize(m_nReduced, 0);
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m_reducedForceElastic.resize(m_nReduced, 0);
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m_reducedForceDamping.resize(m_nReduced, 0);
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m_reducedForceExternal.resize(m_nReduced, 0);
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m_internalDeltaReducedVelocity.resize(m_nReduced, 0);
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m_nodalMass.resize(full_size, 0);
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m_localMomentArm.resize(m_nFull);
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}
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void btReducedDeformableBody::setMassProps(const tDenseArray& mass_array)
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{
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btScalar total_mass = 0;
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btVector3 CoM(0, 0, 0);
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for (int i = 0; i < m_nFull; ++i)
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{
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m_nodalMass[i] = m_rhoScale * mass_array[i];
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m_nodes[i].m_im = mass_array[i] > 0 ? 1.0 / (m_rhoScale * mass_array[i]) : 0;
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total_mass += m_rhoScale * mass_array[i];
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CoM += m_nodalMass[i] * m_nodes[i].m_x;
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}
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// total rigid body mass
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m_mass = total_mass;
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m_inverseMass = total_mass > 0 ? 1.0 / total_mass : 0;
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// original CoM
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m_initialCoM = CoM / total_mass;
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}
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void btReducedDeformableBody::setInertiaProps()
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{
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// make sure the initial CoM is at the origin (0,0,0)
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// for (int i = 0; i < m_nFull; ++i)
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// {
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// m_nodes[i].m_x -= m_initialCoM;
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// }
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// m_initialCoM.setZero();
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m_rigidTransformWorld.setOrigin(m_initialCoM);
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m_interpolationWorldTransform = m_rigidTransformWorld;
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updateLocalInertiaTensorFromNodes();
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// update world inertia tensor
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btMatrix3x3 rotation;
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rotation.setIdentity();
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updateInitialInertiaTensor(rotation);
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updateInertiaTensor();
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m_interpolateInvInertiaTensorWorld = m_invInertiaTensorWorld;
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}
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void btReducedDeformableBody::setRigidVelocity(const btVector3& v)
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{
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m_linearVelocity = v;
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}
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void btReducedDeformableBody::setRigidAngularVelocity(const btVector3& omega)
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{
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m_angularVelocity = omega;
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}
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void btReducedDeformableBody::setStiffnessScale(const btScalar ks)
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{
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m_ksScale = ks;
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}
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void btReducedDeformableBody::setMassScale(const btScalar rho)
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{
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m_rhoScale = rho;
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}
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void btReducedDeformableBody::setFixedNodes(const int n_node)
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{
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m_fixedNodes.push_back(n_node);
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m_nodes[n_node].m_im = 0; // set inverse mass to be zero for the constraint solver.
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}
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void btReducedDeformableBody::setDamping(const btScalar alpha, const btScalar beta)
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{
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m_dampingAlpha = alpha;
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m_dampingBeta = beta;
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}
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void btReducedDeformableBody::internalInitialization()
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{
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// zeroing
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endOfTimeStepZeroing();
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// initialize rest position
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updateRestNodalPositions();
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// initialize local nodal moment arm form the CoM
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updateLocalMomentArm();
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// initialize projection matrix
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updateExternalForceProjectMatrix(false);
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}
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void btReducedDeformableBody::updateLocalMomentArm()
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{
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TVStack delta_x;
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delta_x.resize(m_nFull);
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for (int i = 0; i < m_nFull; ++i)
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{
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for (int k = 0; k < 3; ++k)
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{
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// compute displacement
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delta_x[i][k] = 0;
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for (int j = 0; j < m_nReduced; ++j)
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{
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delta_x[i][k] += m_modes[j][3 * i + k] * m_reducedDofs[j];
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}
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}
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// get new moment arm Sq + x0
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m_localMomentArm[i] = m_x0[i] - m_initialCoM + delta_x[i];
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}
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}
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void btReducedDeformableBody::updateExternalForceProjectMatrix(bool initialized)
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{
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// if not initialized, need to compute both P_A and Cq
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// otherwise, only need to udpate Cq
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if (!initialized)
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{
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// resize
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m_projPA.resize(m_nReduced);
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m_projCq.resize(m_nReduced);
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m_STP.resize(m_nReduced);
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m_MrInvSTP.resize(m_nReduced);
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// P_A
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for (int r = 0; r < m_nReduced; ++r)
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{
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m_projPA[r].resize(3 * m_nFull, 0);
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for (int i = 0; i < m_nFull; ++i)
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{
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btMatrix3x3 mass_scaled_i = Diagonal(1) - Diagonal(m_nodalMass[i] / m_mass);
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btVector3 s_ri(m_modes[r][3 * i], m_modes[r][3 * i + 1], m_modes[r][3 * i + 2]);
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btVector3 prod_i = mass_scaled_i * s_ri;
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for (int k = 0; k < 3; ++k)
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m_projPA[r][3 * i + k] = prod_i[k];
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// btScalar ratio = m_nodalMass[i] / m_mass;
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// m_projPA[r] += btVector3(- m_modes[r][3 * i] * ratio,
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// - m_modes[r][3 * i + 1] * ratio,
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// - m_modes[r][3 * i + 2] * ratio);
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}
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}
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}
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// C(q) is updated once per position update
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for (int r = 0; r < m_nReduced; ++r)
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{
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m_projCq[r].resize(3 * m_nFull, 0);
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for (int i = 0; i < m_nFull; ++i)
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{
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btMatrix3x3 r_star = Cross(m_localMomentArm[i]);
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btVector3 s_ri(m_modes[r][3 * i], m_modes[r][3 * i + 1], m_modes[r][3 * i + 2]);
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btVector3 prod_i = r_star * m_invInertiaTensorWorld * r_star * s_ri;
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for (int k = 0; k < 3; ++k)
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m_projCq[r][3 * i + k] = m_nodalMass[i] * prod_i[k];
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// btVector3 si(m_modes[r][3 * i], m_modes[r][3 * i + 1], m_modes[r][3 * i + 2]);
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// m_projCq[r] += m_nodalMass[i] * si.cross(m_localMomentArm[i]);
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}
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}
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}
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void btReducedDeformableBody::endOfTimeStepZeroing()
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{
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for (int i = 0; i < m_nReduced; ++i)
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{
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m_reducedForceElastic[i] = 0;
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m_reducedForceDamping[i] = 0;
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m_reducedForceExternal[i] = 0;
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m_internalDeltaReducedVelocity[i] = 0;
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m_reducedDofsBuffer[i] = m_reducedDofs[i];
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m_reducedVelocityBuffer[i] = m_reducedVelocity[i];
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}
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// std::cout << "zeroed!\n";
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}
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void btReducedDeformableBody::applyInternalVelocityChanges()
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{
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m_linearVelocity += m_internalDeltaLinearVelocity;
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m_angularVelocity += m_internalDeltaAngularVelocity;
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m_internalDeltaLinearVelocity.setZero();
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m_internalDeltaAngularVelocity.setZero();
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for (int r = 0; r < m_nReduced; ++r)
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{
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m_reducedVelocity[r] += m_internalDeltaReducedVelocity[r];
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m_internalDeltaReducedVelocity[r] = 0;
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}
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}
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void btReducedDeformableBody::predictIntegratedTransform(btScalar dt, btTransform& predictedTransform)
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{
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btTransformUtil::integrateTransform(m_rigidTransformWorld, m_linearVelocity, m_angularVelocity, dt, predictedTransform);
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}
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void btReducedDeformableBody::updateReducedDofs(btScalar solverdt)
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{
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for (int r = 0; r < m_nReduced; ++r)
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{
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m_reducedDofs[r] = m_reducedDofsBuffer[r] + solverdt * m_reducedVelocity[r];
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}
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}
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void btReducedDeformableBody::mapToFullPosition(const btTransform& ref_trans)
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{
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btVector3 origin = ref_trans.getOrigin();
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btMatrix3x3 rotation = ref_trans.getBasis();
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for (int i = 0; i < m_nFull; ++i)
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{
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m_nodes[i].m_x = rotation * m_localMomentArm[i] + origin;
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m_nodes[i].m_q = m_nodes[i].m_x;
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}
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}
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void btReducedDeformableBody::updateReducedVelocity(btScalar solverdt)
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{
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// update reduced velocity
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for (int r = 0; r < m_nReduced; ++r)
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{
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// the reduced mass is always identity!
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btScalar delta_v = 0;
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delta_v = solverdt * (m_reducedForceElastic[r] + m_reducedForceDamping[r]);
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// delta_v = solverdt * (m_reducedForceElastic[r] + m_reducedForceDamping[r] + m_reducedForceExternal[r]);
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m_reducedVelocity[r] = m_reducedVelocityBuffer[r] + delta_v;
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}
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}
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void btReducedDeformableBody::mapToFullVelocity(const btTransform& ref_trans)
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{
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// compute the reduced contribution to the angular velocity
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// btVector3 sum_linear(0, 0, 0);
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// btVector3 sum_angular(0, 0, 0);
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// m_linearVelocityFromReduced.setZero();
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// m_angularVelocityFromReduced.setZero();
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// for (int i = 0; i < m_nFull; ++i)
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// {
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// btVector3 r_com = ref_trans.getBasis() * m_localMomentArm[i];
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// btMatrix3x3 r_star = Cross(r_com);
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// btVector3 v_from_reduced(0, 0, 0);
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// for (int k = 0; k < 3; ++k)
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// {
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// for (int r = 0; r < m_nReduced; ++r)
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// {
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// v_from_reduced[k] += m_modes[r][3 * i + k] * m_reducedVelocity[r];
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// }
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// }
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// btVector3 delta_linear = m_nodalMass[i] * v_from_reduced;
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// btVector3 delta_angular = m_nodalMass[i] * (r_star * ref_trans.getBasis() * v_from_reduced);
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// sum_linear += delta_linear;
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// sum_angular += delta_angular;
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// // std::cout << "delta_linear: " << delta_linear[0] << "\t" << delta_linear[1] << "\t" << delta_linear[2] << "\n";
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// // std::cout << "delta_angular: " << delta_angular[0] << "\t" << delta_angular[1] << "\t" << delta_angular[2] << "\n";
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// // std::cout << "sum_linear: " << sum_linear[0] << "\t" << sum_linear[1] << "\t" << sum_linear[2] << "\n";
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// // std::cout << "sum_angular: " << sum_angular[0] << "\t" << sum_angular[1] << "\t" << sum_angular[2] << "\n";
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// }
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// m_linearVelocityFromReduced = 1.0 / m_mass * (ref_trans.getBasis() * sum_linear);
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// m_angularVelocityFromReduced = m_interpolateInvInertiaTensorWorld * sum_angular;
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// m_linearVelocity -= m_linearVelocityFromReduced;
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// m_angularVelocity -= m_angularVelocityFromReduced;
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for (int i = 0; i < m_nFull; ++i)
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{
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m_nodes[i].m_v = computeNodeFullVelocity(ref_trans, i);
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}
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}
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const btVector3 btReducedDeformableBody::computeTotalAngularMomentum() const
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{
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btVector3 L_rigid = m_invInertiaTensorWorld.inverse() * m_angularVelocity;
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btVector3 L_reduced(0, 0, 0);
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btMatrix3x3 omega_prime_star = Cross(m_angularVelocityFromReduced);
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for (int i = 0; i < m_nFull; ++i)
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{
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btVector3 r_com = m_rigidTransformWorld.getBasis() * m_localMomentArm[i];
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btMatrix3x3 r_star = Cross(r_com);
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btVector3 v_from_reduced(0, 0, 0);
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for (int k = 0; k < 3; ++k)
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{
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for (int r = 0; r < m_nReduced; ++r)
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{
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v_from_reduced[k] += m_modes[r][3 * i + k] * m_reducedVelocity[r];
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}
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}
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L_reduced += m_nodalMass[i] * (r_star * (m_rigidTransformWorld.getBasis() * v_from_reduced - omega_prime_star * r_com));
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// L_reduced += m_nodalMass[i] * (r_star * (m_rigidTransformWorld.getBasis() * v_from_reduced));
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}
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return L_rigid + L_reduced;
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}
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const btVector3 btReducedDeformableBody::computeNodeFullVelocity(const btTransform& ref_trans, int n_node) const
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{
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btVector3 v_from_reduced(0, 0, 0);
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btVector3 r_com = ref_trans.getBasis() * m_localMomentArm[n_node];
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// compute velocity contributed by the reduced velocity
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for (int k = 0; k < 3; ++k)
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{
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for (int r = 0; r < m_nReduced; ++r)
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{
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v_from_reduced[k] += m_modes[r][3 * n_node + k] * m_reducedVelocity[r];
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}
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}
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// get new velocity
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btVector3 vel = m_angularVelocity.cross(r_com) +
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ref_trans.getBasis() * v_from_reduced +
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m_linearVelocity;
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return vel;
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}
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const btVector3 btReducedDeformableBody::internalComputeNodeDeltaVelocity(const btTransform& ref_trans, int n_node) const
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{
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btVector3 deltaV_from_reduced(0, 0, 0);
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btVector3 r_com = ref_trans.getBasis() * m_localMomentArm[n_node];
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// compute velocity contributed by the reduced velocity
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for (int k = 0; k < 3; ++k)
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{
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for (int r = 0; r < m_nReduced; ++r)
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{
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deltaV_from_reduced[k] += m_modes[r][3 * n_node + k] * m_internalDeltaReducedVelocity[r];
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}
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}
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// get delta velocity
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btVector3 deltaV = m_internalDeltaAngularVelocity.cross(r_com) +
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ref_trans.getBasis() * deltaV_from_reduced +
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m_internalDeltaLinearVelocity;
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return deltaV;
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}
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void btReducedDeformableBody::proceedToTransform(btScalar dt, bool end_of_time_step)
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{
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btTransformUtil::integrateTransform(m_rigidTransformWorld, m_linearVelocity, m_angularVelocity, dt, m_interpolationWorldTransform);
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updateInertiaTensor();
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// m_interpolateInvInertiaTensorWorld = m_interpolationWorldTransform.getBasis().scaled(m_invInertiaLocal) * m_interpolationWorldTransform.getBasis().transpose();
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m_rigidTransformWorld = m_interpolationWorldTransform;
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m_invInertiaTensorWorld = m_interpolateInvInertiaTensorWorld;
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}
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void btReducedDeformableBody::transformTo(const btTransform& trs)
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{
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btTransform current_transform = getRigidTransform();
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btTransform new_transform(trs.getBasis() * current_transform.getBasis().transpose(),
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trs.getOrigin() - current_transform.getOrigin());
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transform(new_transform);
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}
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void btReducedDeformableBody::transform(const btTransform& trs)
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{
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m_transform_lock = true;
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// transform mesh
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{
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const btScalar margin = getCollisionShape()->getMargin();
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ATTRIBUTE_ALIGNED16(btDbvtVolume)
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vol;
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btVector3 CoM = m_rigidTransformWorld.getOrigin();
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btVector3 translation = trs.getOrigin();
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btMatrix3x3 rotation = trs.getBasis();
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for (int i = 0; i < m_nodes.size(); ++i)
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{
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Node& n = m_nodes[i];
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n.m_x = rotation * (n.m_x - CoM) + CoM + translation;
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n.m_q = rotation * (n.m_q - CoM) + CoM + translation;
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n.m_n = rotation * n.m_n;
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vol = btDbvtVolume::FromCR(n.m_x, margin);
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m_ndbvt.update(n.m_leaf, vol);
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}
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updateNormals();
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updateBounds();
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updateConstants();
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}
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// update modes
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updateModesByRotation(trs.getBasis());
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// update inertia tensor
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updateInitialInertiaTensor(trs.getBasis());
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updateInertiaTensor();
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m_interpolateInvInertiaTensorWorld = m_invInertiaTensorWorld;
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// update rigid frame (No need to update the rotation. Nodes have already been updated.)
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m_rigidTransformWorld.setOrigin(m_initialCoM + trs.getOrigin());
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m_interpolationWorldTransform = m_rigidTransformWorld;
|
|
m_initialCoM = m_rigidTransformWorld.getOrigin();
|
|
|
|
internalInitialization();
|
|
}
|
|
|
|
void btReducedDeformableBody::scale(const btVector3& scl)
|
|
{
|
|
// Scaling the mesh after transform is applied is not allowed
|
|
btAssert(!m_transform_lock);
|
|
|
|
// scale the mesh
|
|
{
|
|
const btScalar margin = getCollisionShape()->getMargin();
|
|
ATTRIBUTE_ALIGNED16(btDbvtVolume)
|
|
vol;
|
|
|
|
btVector3 CoM = m_rigidTransformWorld.getOrigin();
|
|
|
|
for (int i = 0; i < m_nodes.size(); ++i)
|
|
{
|
|
Node& n = m_nodes[i];
|
|
n.m_x = (n.m_x - CoM) * scl + CoM;
|
|
n.m_q = (n.m_q - CoM) * scl + CoM;
|
|
vol = btDbvtVolume::FromCR(n.m_x, margin);
|
|
m_ndbvt.update(n.m_leaf, vol);
|
|
}
|
|
updateNormals();
|
|
updateBounds();
|
|
updateConstants();
|
|
initializeDmInverse();
|
|
}
|
|
|
|
// update inertia tensor
|
|
updateLocalInertiaTensorFromNodes();
|
|
|
|
btMatrix3x3 id;
|
|
id.setIdentity();
|
|
updateInitialInertiaTensor(id); // there is no rotation, but the local inertia tensor has changed
|
|
updateInertiaTensor();
|
|
m_interpolateInvInertiaTensorWorld = m_invInertiaTensorWorld;
|
|
|
|
internalInitialization();
|
|
}
|
|
|
|
void btReducedDeformableBody::setTotalMass(btScalar mass, bool fromfaces)
|
|
{
|
|
// Changing the total mass after transform is applied is not allowed
|
|
btAssert(!m_transform_lock);
|
|
|
|
btScalar scale_ratio = mass / m_mass;
|
|
|
|
// update nodal mass
|
|
for (int i = 0; i < m_nFull; ++i)
|
|
{
|
|
m_nodalMass[i] *= scale_ratio;
|
|
}
|
|
m_mass = mass;
|
|
m_inverseMass = mass > 0 ? 1.0 / mass : 0;
|
|
|
|
// update inertia tensors
|
|
updateLocalInertiaTensorFromNodes();
|
|
|
|
btMatrix3x3 id;
|
|
id.setIdentity();
|
|
updateInitialInertiaTensor(id); // there is no rotation, but the local inertia tensor has changed
|
|
updateInertiaTensor();
|
|
m_interpolateInvInertiaTensorWorld = m_invInertiaTensorWorld;
|
|
|
|
internalInitialization();
|
|
}
|
|
|
|
void btReducedDeformableBody::updateRestNodalPositions()
|
|
{
|
|
// update reset nodal position
|
|
m_x0.resize(m_nFull);
|
|
for (int i = 0; i < m_nFull; ++i)
|
|
{
|
|
m_x0[i] = m_nodes[i].m_x;
|
|
}
|
|
}
|
|
|
|
// reference notes:
|
|
// https://ocw.mit.edu/courses/aeronautics-and-astronautics/16-07-dynamics-fall-2009/lecture-notes/MIT16_07F09_Lec26.pdf
|
|
void btReducedDeformableBody::updateLocalInertiaTensorFromNodes()
|
|
{
|
|
btMatrix3x3 inertia_tensor;
|
|
inertia_tensor.setZero();
|
|
|
|
for (int p = 0; p < m_nFull; ++p)
|
|
{
|
|
btMatrix3x3 particle_inertia;
|
|
particle_inertia.setZero();
|
|
|
|
btVector3 r = m_nodes[p].m_x - m_initialCoM;
|
|
|
|
particle_inertia[0][0] = m_nodalMass[p] * (r[1] * r[1] + r[2] * r[2]);
|
|
particle_inertia[1][1] = m_nodalMass[p] * (r[0] * r[0] + r[2] * r[2]);
|
|
particle_inertia[2][2] = m_nodalMass[p] * (r[0] * r[0] + r[1] * r[1]);
|
|
|
|
particle_inertia[0][1] = - m_nodalMass[p] * (r[0] * r[1]);
|
|
particle_inertia[0][2] = - m_nodalMass[p] * (r[0] * r[2]);
|
|
particle_inertia[1][2] = - m_nodalMass[p] * (r[1] * r[2]);
|
|
|
|
particle_inertia[1][0] = particle_inertia[0][1];
|
|
particle_inertia[2][0] = particle_inertia[0][2];
|
|
particle_inertia[2][1] = particle_inertia[1][2];
|
|
|
|
inertia_tensor += particle_inertia;
|
|
}
|
|
m_invInertiaLocal = inertia_tensor.inverse();
|
|
}
|
|
|
|
void btReducedDeformableBody::updateInitialInertiaTensor(const btMatrix3x3& rotation)
|
|
{
|
|
// m_invInertiaTensorWorldInitial = rotation.scaled(m_invInertiaLocal) * rotation.transpose();
|
|
m_invInertiaTensorWorldInitial = rotation * m_invInertiaLocal * rotation.transpose();
|
|
}
|
|
|
|
void btReducedDeformableBody::updateModesByRotation(const btMatrix3x3& rotation)
|
|
{
|
|
for (int r = 0; r < m_nReduced; ++r)
|
|
{
|
|
for (int i = 0; i < m_nFull; ++i)
|
|
{
|
|
btVector3 nodal_disp(m_modes[r][3 * i], m_modes[r][3 * i + 1], m_modes[r][3 * i + 2]);
|
|
nodal_disp = rotation * nodal_disp;
|
|
|
|
for (int k = 0; k < 3; ++k)
|
|
{
|
|
m_modes[r][3 * i + k] = nodal_disp[k];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void btReducedDeformableBody::updateInertiaTensor()
|
|
{
|
|
m_invInertiaTensorWorld = m_rigidTransformWorld.getBasis() * m_invInertiaTensorWorldInitial * m_rigidTransformWorld.getBasis().transpose();
|
|
}
|
|
|
|
void btReducedDeformableBody::applyDamping(btScalar timeStep)
|
|
{
|
|
m_linearVelocity *= btScalar(1) - m_linearDamping;
|
|
m_angularDamping *= btScalar(1) - m_angularDamping;
|
|
}
|
|
|
|
void btReducedDeformableBody::applyCentralImpulse(const btVector3& impulse)
|
|
{
|
|
m_linearVelocity += impulse * m_linearFactor * m_inverseMass;
|
|
#if defined(BT_CLAMP_VELOCITY_TO) && BT_CLAMP_VELOCITY_TO > 0
|
|
clampVelocity(m_linearVelocity);
|
|
#endif
|
|
}
|
|
|
|
void btReducedDeformableBody::applyTorqueImpulse(const btVector3& torque)
|
|
{
|
|
m_angularVelocity += m_interpolateInvInertiaTensorWorld * torque * m_angularFactor;
|
|
#if defined(BT_CLAMP_VELOCITY_TO) && BT_CLAMP_VELOCITY_TO > 0
|
|
clampVelocity(m_angularVelocity);
|
|
#endif
|
|
}
|
|
|
|
void btReducedDeformableBody::internalApplyRigidImpulse(const btVector3& impulse, const btVector3& rel_pos)
|
|
{
|
|
if (m_inverseMass == btScalar(0.))
|
|
{
|
|
std::cout << "something went wrong...probably didn't initialize?\n";
|
|
btAssert(false);
|
|
}
|
|
// delta linear velocity
|
|
m_internalDeltaLinearVelocity += impulse * m_linearFactor * m_inverseMass;
|
|
// delta angular velocity
|
|
btVector3 torque = rel_pos.cross(impulse * m_linearFactor);
|
|
m_internalDeltaAngularVelocity += m_interpolateInvInertiaTensorWorld * torque * m_angularFactor;
|
|
}
|
|
|
|
btVector3 btReducedDeformableBody::getRelativePos(int n_node)
|
|
{
|
|
btMatrix3x3 rotation = m_interpolationWorldTransform.getBasis();
|
|
btVector3 ri = rotation * m_localMomentArm[n_node];
|
|
return ri;
|
|
}
|
|
|
|
btMatrix3x3 btReducedDeformableBody::getImpulseFactor(int n_node)
|
|
{
|
|
// relative position
|
|
btMatrix3x3 rotation = m_interpolationWorldTransform.getBasis();
|
|
btVector3 ri = rotation * m_localMomentArm[n_node];
|
|
btMatrix3x3 ri_skew = Cross(ri);
|
|
|
|
// calculate impulse factor
|
|
// rigid part
|
|
btScalar inv_mass = m_nodalMass[n_node] > btScalar(0) ? btScalar(1) / m_mass : btScalar(0);
|
|
btMatrix3x3 K1 = Diagonal(inv_mass);
|
|
K1 -= ri_skew * m_interpolateInvInertiaTensorWorld * ri_skew;
|
|
|
|
// reduced deformable part
|
|
btMatrix3x3 SA;
|
|
SA.setZero();
|
|
for (int i = 0; i < 3; ++i)
|
|
{
|
|
for (int j = 0; j < 3; ++j)
|
|
{
|
|
for (int r = 0; r < m_nReduced; ++r)
|
|
{
|
|
SA[i][j] += m_modes[r][3 * n_node + i] * (m_projPA[r][3 * n_node + j] + m_projCq[r][3 * n_node + j]);
|
|
}
|
|
}
|
|
}
|
|
btMatrix3x3 RSARinv = rotation * SA * rotation.transpose();
|
|
|
|
|
|
TVStack omega_helper; // Sum_i m_i r*_i R S_i
|
|
omega_helper.resize(m_nReduced);
|
|
for (int r = 0; r < m_nReduced; ++r)
|
|
{
|
|
omega_helper[r].setZero();
|
|
for (int i = 0; i < m_nFull; ++i)
|
|
{
|
|
btMatrix3x3 mi_rstar_i = rotation * Cross(m_localMomentArm[i]) * m_nodalMass[i];
|
|
btVector3 s_ri(m_modes[r][3 * i], m_modes[r][3 * i + 1], m_modes[r][3 * i + 2]);
|
|
omega_helper[r] += mi_rstar_i * rotation * s_ri;
|
|
}
|
|
}
|
|
|
|
btMatrix3x3 sum_multiply_A;
|
|
sum_multiply_A.setZero();
|
|
for (int i = 0; i < 3; ++i)
|
|
{
|
|
for (int j = 0; j < 3; ++j)
|
|
{
|
|
for (int r = 0; r < m_nReduced; ++r)
|
|
{
|
|
sum_multiply_A[i][j] += omega_helper[r][i] * (m_projPA[r][3 * n_node + j] + m_projCq[r][3 * n_node + j]);
|
|
}
|
|
}
|
|
}
|
|
|
|
btMatrix3x3 K2 = RSARinv + ri_skew * m_interpolateInvInertiaTensorWorld * sum_multiply_A * rotation.transpose();
|
|
|
|
return m_rigidOnly ? K1 : K1 + K2;
|
|
}
|
|
|
|
void btReducedDeformableBody::internalApplyFullSpaceImpulse(const btVector3& impulse, const btVector3& rel_pos, int n_node, btScalar dt)
|
|
{
|
|
if (!m_rigidOnly)
|
|
{
|
|
// apply impulse force
|
|
applyFullSpaceNodalForce(impulse / dt, n_node);
|
|
|
|
// update delta damping force
|
|
tDenseArray reduced_vel_tmp;
|
|
reduced_vel_tmp.resize(m_nReduced);
|
|
for (int r = 0; r < m_nReduced; ++r)
|
|
{
|
|
reduced_vel_tmp[r] = m_reducedVelocity[r] + m_internalDeltaReducedVelocity[r];
|
|
}
|
|
applyReducedDampingForce(reduced_vel_tmp);
|
|
// applyReducedDampingForce(m_internalDeltaReducedVelocity);
|
|
|
|
// delta reduced velocity
|
|
for (int r = 0; r < m_nReduced; ++r)
|
|
{
|
|
// The reduced mass is always identity!
|
|
m_internalDeltaReducedVelocity[r] += dt * (m_reducedForceDamping[r] + m_reducedForceExternal[r]);
|
|
}
|
|
}
|
|
|
|
internalApplyRigidImpulse(impulse, rel_pos);
|
|
}
|
|
|
|
void btReducedDeformableBody::applyFullSpaceNodalForce(const btVector3& f_ext, int n_node)
|
|
{
|
|
// f_local = R^-1 * f_ext //TODO: interpoalted transfrom
|
|
// btVector3 f_local = m_rigidTransformWorld.getBasis().transpose() * f_ext;
|
|
btVector3 f_local = m_interpolationWorldTransform.getBasis().transpose() * f_ext;
|
|
|
|
// f_ext_r = [S^T * P]_{n_node} * f_local
|
|
tDenseArray f_ext_r;
|
|
f_ext_r.resize(m_nReduced, 0);
|
|
for (int r = 0; r < m_nReduced; ++r)
|
|
{
|
|
m_reducedForceExternal[r] = 0;
|
|
for (int k = 0; k < 3; ++k)
|
|
{
|
|
f_ext_r[r] += (m_projPA[r][3 * n_node + k] + m_projCq[r][3 * n_node + k]) * f_local[k];
|
|
}
|
|
|
|
m_reducedForceExternal[r] += f_ext_r[r];
|
|
}
|
|
}
|
|
|
|
void btReducedDeformableBody::applyRigidGravity(const btVector3& gravity, btScalar dt)
|
|
{
|
|
// update rigid frame velocity
|
|
m_linearVelocity += dt * gravity;
|
|
}
|
|
|
|
void btReducedDeformableBody::applyReducedElasticForce(const tDenseArray& reduce_dofs)
|
|
{
|
|
for (int r = 0; r < m_nReduced; ++r)
|
|
{
|
|
m_reducedForceElastic[r] = - m_ksScale * m_Kr[r] * reduce_dofs[r];
|
|
}
|
|
}
|
|
|
|
void btReducedDeformableBody::applyReducedDampingForce(const tDenseArray& reduce_vel)
|
|
{
|
|
for (int r = 0; r < m_nReduced; ++r)
|
|
{
|
|
m_reducedForceDamping[r] = - m_dampingBeta * m_ksScale * m_Kr[r] * reduce_vel[r];
|
|
}
|
|
}
|
|
|
|
btScalar btReducedDeformableBody::getTotalMass() const
|
|
{
|
|
return m_mass;
|
|
}
|
|
|
|
btTransform& btReducedDeformableBody::getRigidTransform()
|
|
{
|
|
return m_rigidTransformWorld;
|
|
}
|
|
|
|
const btVector3& btReducedDeformableBody::getLinearVelocity() const
|
|
{
|
|
return m_linearVelocity;
|
|
}
|
|
|
|
const btVector3& btReducedDeformableBody::getAngularVelocity() const
|
|
{
|
|
return m_angularVelocity;
|
|
}
|
|
|
|
void btReducedDeformableBody::disableReducedModes(const bool rigid_only)
|
|
{
|
|
m_rigidOnly = rigid_only;
|
|
}
|
|
|
|
bool btReducedDeformableBody::isReducedModesOFF() const
|
|
{
|
|
return m_rigidOnly;
|
|
} |