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MpmCore.cpp
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#include "stdafx.h"
GridField::GridField( const Vector3f& grid_size, const Vector3f& grid_min, const Vector3i& grid_division, int boundary)
{
this->grid_size=grid_size;
this->grid_min=grid_min;
this->grid_division[0]=grid_division[0];
this->grid_division[1]=grid_division[1];
this->grid_division[2]=grid_division[2];
this->grid_max=grid_min + grid_size.cwiseProduct(grid_division.cast<float>());
this->boundary = boundary;
int totalSize = grid_division[0]*grid_division[1]*grid_division[2];
gridBuffer = new GridNode[totalSize];
GridNode* pn = gridBuffer;
grids.resize(boost::extents[grid_division[0]][grid_division[1]][grid_division[2]]);
for(int i=0;i<grids.shape()[0];i++)
for(int j=0;j<grids.shape()[1];j++)
for(int k=0;k<grids.shape()[2];k++)
{
grids[i][j][k]= pn;
pn++;
}
}
GridField::GridField()
{
grid_size.setZero();
grid_division[0] = grid_division[1] = grid_division[2] = 0;
boundary = 0;
gridBuffer = NULL;
}
void GridField::clear()
{
// for(int i=0;i<grids.shape()[0];i++)
// for(int j=0;j<grids.shape()[1];j++)
// for(int k=0;k<grids.shape()[2];k++)
// {
// if(grids[i][j][k])
// {
// delete grids[i][j][k];
// }
// }
if (gridBuffer)
{
delete[] gridBuffer;
gridBuffer = NULL;
}
}
GridField::~GridField()
{
clear();
}
float MpmCore::NX_bspline( float m )
{
m=fabs(m);
float m2 = m*m;
float m3 = m2*m;
float ret;
if(m<1.0f)
ret= m3*0.5 - m2 + 2.0/3.0;
else if(m<2.0f)
ret= m3/(-6)+ m2 - m*2 + 4.0/3.0;
else
return 0;
if(ret<0.0000001f)
return 0;
return ret;
}
float MpmCore::dNX_bsplineslope( float m )
{
float abs_m=fabs(m);
if(abs_m<1)
return 1.5*m*abs_m-2*m;
else if(abs_m<2)
return -m*abs_m/2+m*2-2*m/abs_m;
else
return 0;
}
float MpmCore::weight( Vector3f& d_xp )
{
return NX_bspline(d_xp[0])*NX_bspline(d_xp[1])*NX_bspline(d_xp[2]);
}
Vector3f MpmCore::weight_gradientF( Vector3f& d_xp )
{
float w0 = NX_bspline(d_xp[0]);
float w1 = NX_bspline(d_xp[1]);
float w2 = NX_bspline(d_xp[2]);
return Vector3f(
dNX_bsplineslope(d_xp[0])*w1*w2,
dNX_bsplineslope(d_xp[1])*w2*w0,
dNX_bsplineslope(d_xp[2])*w0*w1);
}
Matrix3f MpmCore::cauchy_stress( Matrix3f& Fe, Matrix3f& Fp, float particle_volume )
{
float det_fe=Fe.determinant();
float det_fp=Fp.determinant();
//formula 2
float factor= exp(ctrl_params.hardening*(1-det_fp));
float miu = factor*ctrl_params.miu;
float lambda= factor*ctrl_params.lambda;
//polar decomposition FE=RE SE
Eigen::JacobiSVD<Eigen::Matrix3f> svd(Fe, Eigen::ComputeFullU| Eigen::ComputeFullV);
Eigen::Matrix3f Re = svd.matrixU()*svd.matrixV().transpose();
Matrix3f I;
I.setIdentity();
//???? dx of fomular 1
//return (Fe-Re)*Fe.transpose()*2*miu + Matrix3f(lambda*det_fe*(det_fe-1));
return ((Fe-Re)*Fe.transpose()*(2*miu) + I*(lambda*det_fe*(det_fe-1)))*(particle_volume*-1);
}
void MpmCore::init_particle_volume_velocity()
{
int totalCell = grid->grid_division[0] * grid->grid_division[1] * grid->grid_division[2];
GridNode zeroNode;
tbb::parallel_for(tbb::blocked_range<int>(0, totalCell, 2500), [&](tbb::blocked_range<int>& r)
{
GridNode* pCell = grid->getNode(0,0,0) + r.begin();
for(int idx = r.begin(); idx != r.end(); idx++, pCell++)
{
pCell->mass=0;
}
});
for(int pit=0;pit<particles.size();pit++)
{
Particle* ptcl = &particles[pit];
Vector3f p_grid_index_f= ptcl->getGridIdx(grid->grid_min,grid->grid_size);
Vector3i p_grid_index_i= ptcl->getGridIdx_int(grid->grid_min,grid->grid_size);
for(int z=-2; z<=2;z++)
{
for(int y=-2; y<=2;y++)
{
for(int x=-2; x<=2;x++)
{
Vector3i index=p_grid_index_i+Vector3i(x,y,z);
if(inGrid(index, grid->grid_division))
{
Vector3f xp=(ptcl->position - grid->grid_size.cwiseProduct(Vector3f(index[0],index[1],index[2]))-grid->grid_min).cwiseQuotient(grid->grid_size);
float weight_p=weight(xp);
grid->getNode(index[0], index[1], index[2])->mass +=
weight_p * ptcl->pmass;
}
}
}
}
}
const float cellVolume = grid->grid_size[0] * grid->grid_size[1] * grid->grid_size[2];
for(int pit=0;pit<particles.size();pit++)
{
Particle* ptcl = &particles[pit];
float density=0.f;
Vector3f p_grid_index_f= ptcl->getGridIdx(grid->grid_min,grid->grid_size);
Vector3i p_grid_index_i= ptcl->getGridIdx_int(grid->grid_min,grid->grid_size);
for(int z=-2; z<=2;z++)
{
for(int y=-2; y<=2;y++)
{
for(int x=-2; x<=2;x++)
{
Vector3i index=p_grid_index_i+Vector3i(x,y,z);
if(inGrid(index, grid->grid_division))
{
Vector3f xp=(ptcl->position
- grid->grid_size.cwiseProduct(Vector3f(index[0],index[1],index[2]))
- grid->grid_min).cwiseQuotient(grid->grid_size);
float weight_p= weight(xp);
density+=grid->getNode(index[0],index[1],index[2])->mass *
weight_p / cellVolume;
}
}
}
}
ptcl->volume= ptcl->pmass/density;
}
}
void MpmCore::parallel_from_particles_to_grid()
{
// clock_t t0 = clock(), t1;
int totalCell = grid->grid_division[0] * grid->grid_division[1] * grid->grid_division[2];
GridNode zeroNode;
tbb::parallel_for(tbb::blocked_range<int>(0, totalCell, 2500), [&](tbb::blocked_range<int>& r)
{
GridNode* pCell = grid->getNode(0,0,0) + r.begin();
for(int idx = r.begin(); idx != r.end(); idx++, pCell++)
{
pCell->mass=0;
pCell->external_force.setZero();
pCell->velocity_old.setZero();
pCell->velocity_new.setZero();
pCell->active=false;
}
});
// t1 = clock();
// PRINT_F("--init %f s", (t1-t0)/ float(CLOCKS_PER_SEC));
// t0 = t1;
std::vector<ParticleTemp>& ptclTemp = m_particleTemp;
if (m_particleTemp.size() != particles.size())
{
ptclTemp.resize(particles.size());
}
tbb::parallel_for(tbb::blocked_range<int>(0, particles.size(), 2500), [&](tbb::blocked_range<int>& r)
{
for(int pit = r.begin(); pit != r.end(); pit++)
{
Particle* ptcl = &particles[pit];
ParticleTemp& ptclRes = ptclTemp[pit];
if (!ptcl->isValid)
continue;
Vector3f p_grid_index_f=ptcl->getGridIdx(grid->grid_min,grid->grid_size);
Vector3i p_grid_index_i=ptcl->getGridIdx_int(grid->grid_min,grid->grid_size);
Matrix3f cauchyStress = cauchy_stress(ptcl->Fe, ptcl->Fp, ptcl->volume);
Vector3i cornerIdx = p_grid_index_i + Vector3i(-neighbour,-neighbour,-neighbour);
ptclRes.cornerCell = grid->getNode(cornerIdx[0], cornerIdx[1], cornerIdx[2]);
for(int z=-neighbour, ithNeigh = 0; z<=neighbour;z++)
{
for(int y=-neighbour; y<=neighbour;y++)
{
for(int x=-neighbour; x<=neighbour;x++, ithNeigh++)
{
Vector3i index=p_grid_index_i+Vector3i(x,y,z);
if (index[0] < 0 || index[0] >= grid->grid_division[0])
ptclRes.weightX[x+neighbour] = -1.f;
else if(index[1] < 0 || index[1] >= grid->grid_division[1])
ptclRes.weightY[y+neighbour] = -1.f;
else if(index[2] < 0 || index[2] >= grid->grid_division[2])
ptclRes.weightZ[z+neighbour] = -1.f;
else
{
Vector3f xp=(ptcl->position - grid->grid_size.cwiseProduct(Vector3f(index[0],index[1],index[2])) -
grid->grid_min).cwiseQuotient(grid->grid_size);
//ptclRes.weight[ithNeigh] = weight(xp);
ptclRes.weightX[x+neighbour] = NX_bspline(xp[0]);
ptclRes.weightY[y+neighbour] = NX_bspline(xp[1]);
ptclRes.weightZ[z+neighbour] = NX_bspline(xp[2]);
Vector3f gradientWeight = weight_gradientF(xp).cwiseQuotient(grid->grid_size);
ptclRes.gradientWeight[ithNeigh] = cauchyStress * gradientWeight;
}
}
}
}
}
});
// t1 = clock();
// PRINT_F("--ptcl2grid parallel %f s", (t1-t0)/ float(CLOCKS_PER_SEC));
// t0 = t1;
const int nx = grid->grid_division[0];
const int ny = grid->grid_division[1];
const int w = neighbour*2+1;
for(int pit=0;pit<particles.size();pit++)
{
Particle* ptcl = &particles[pit];
if(!ptcl->isValid)
continue;
ParticleTemp& ptclRes = ptclTemp[pit];
GridNode* pCell = ptclRes.cornerCell;
for(int z=0, ithNeigh = 0; z<w; z++, pCell += nx*(ny-w))
{
const float weightZ = ptclRes.weightZ[z];
for(int y=0; y<w; y++, pCell += nx-w)
{
const float weightY = ptclRes.weightY[y];
const float weightYZ= weightY * weightZ;
for(int x=0; x<w;x++, ithNeigh++, pCell++)
{
//if(ptclRes.weight[ithNeigh] > 0.f)
const float weightX = ptclRes.weightX[x];
if (weightX > 0.f &&
weightY > 0.f &&
weightZ > 0.f)
{
// float weight_p = ptclRes.weight[ithNeigh]* ptcl->pmass;
float weight_p = weightX * weightYZ * ptcl->pmass;
pCell->mass += weight_p;
//now velocity is v*m. we need to divide m before use it
pCell->velocity_old += weight_p * ptcl->velocity;
//fomular 6
pCell->external_force += ptclRes.gradientWeight[ithNeigh];
}
}
}
}
}
// t1 = clock();
// PRINT_F("--collect %f s", (t1-t0)/ float(CLOCKS_PER_SEC));
}
void MpmCore::from_particles_to_grid()
{
for(int x=0;x<grid->grid_division[0];x++)
{
for(int y=0;y<grid->grid_division[1];y++)
{
for(int z=0;z<grid->grid_division[2];z++)
{
GridNode* pCell = grid->getNode(x,y,z);
pCell->mass=0;
pCell->external_force.setZero();
pCell->velocity_old.setZero();
pCell->velocity_new.setZero();
pCell->active=false;
}
}
}
for(int pit=0;pit<particles.size();pit++)
{
Particle* ptcl = &particles[pit];
if(!ptcl->isValid)
continue;
Vector3f p_grid_index_f=ptcl->getGridIdx(grid->grid_min,grid->grid_size);
Vector3i p_grid_index_i=ptcl->getGridIdx_int(grid->grid_min,grid->grid_size);
Matrix3f cauchyStress=cauchy_stress(ptcl->Fe, ptcl->Fp, ptcl->volume);
for(int z=-2; z<=2;z++)
{
for(int y=-2; y<=2;y++)
{
for(int x=-2; x<=2;x++)
{
Vector3i index=p_grid_index_i+Vector3i(x,y,z);
if(inGrid(index, grid->grid_division))
{
Vector3f xp=(ptcl->position - grid->grid_size.cwiseProduct(Vector3f(index[0],index[1],index[2])) - grid->grid_min).cwiseQuotient(grid->grid_size);
float weight_p=weight(xp);
Vector3f gradient_weight=weight_gradientF(xp).cwiseQuotient(grid->grid_size);
GridNode* pCell = grid->getNode(index[0], index[1], index[2]);
pCell->mass+=weight_p*ptcl->pmass;
//now velocity is v*m. we need to divide m before use it
pCell->velocity_old+=weight_p*ptcl->pmass*ptcl->velocity;
//fomular 6
pCell->external_force+=cauchyStress*gradient_weight;
}
}
}
}
}
}
void MpmCore::compute_grid_velocity()
{
//fstream fs("G://snow//log.txt",std::ios_base::app);
//fs<<"frame "<<ctrl_params.frame<<":"<<endl;
for(int x=0;x<grid->grids.shape()[0];x++)
for(int y=0;y<grid->grids.shape()[1];y++)
for(int z=0;z<grid->grids.shape()[2];z++)
{
GridNode* cell = grid->getNode(x,y,z);
if(cell->mass>0.f)
{
//as velocity is v*m in step 1. we need to divide m before use it
cell->velocity_old/=cell->mass;
cell->external_force+=ctrl_params.gravity*cell->mass;
//v=v+f/m*deltaT
cell->velocity_new=cell->velocity_old+cell->external_force/cell->mass*ctrl_params.deltaT;
cell->active=true;
//fs<<x<<","<<y<<","<<z<<":"<<grid->grids[x][y][z]->velocity_old[0]<<","<<grid->grids[x][y][z]->velocity_old[1]<<","<<grid->grids[x][y][z]->velocity_old[2]<<"|"<<
// //external_force_old[0]<<","<<external_force_old[1]<<","<<external_force_old[2]<<"|"<<
// grid->grids[x][y][z]->mass<<endl;
}
}
//fs<<endl;
//fs.flush();
//fs.close();
}
float MpmCore::getSDFPhai_interploted(Vector3f& pos, int time, Vector3f& vco_log, Vector3f& pos_cur_log, Vector3f& grid_cur_log,
Vector3f& pos_next_log, Vector3f& grid_next_log, Vector3f& sdf_log)
{
Vector3i grid_idx = ((pos - grid->grid_min).cwiseQuotient(grid->grid_size)).cast<int>();
GridNode* cell = grid->inGrid(grid_idx) ? grid->getNode(grid_idx[0],grid_idx[1],grid_idx[2]) : NULL;
//velocity of collider
Vector3f vco;
if(cell)
{
vco =(1-ctrl_params.iteplote)* cell->collision_velocity_prev
+ctrl_params.iteplote * cell->collision_velocity;
}
else
vco.setZero();
//pos of this maya frame
Vector3f pos_cur = pos - ctrl_params.iteplote * ctrl_params.maya_deltaT * vco;
Vector3f grid_idx_cur= grid->getGridIdx(pos_cur);
float sdf_cur= getSDFPhaiPrev(grid_idx_cur.cast<int>());
//pos of next maya frame
Vector3f pos_next=pos+(1-ctrl_params.iteplote)*ctrl_params.maya_deltaT*vco;
Vector3f grid_idx_next=grid->getGridIdx(pos_next);
float sdf_next=getSDFPhaiNow(grid_idx_next.cast<int>());
float sdf = (1.f - ctrl_params.iteplote) * sdf_cur + ctrl_params.iteplote * sdf_next;
vco_log=vco;
pos_cur_log=pos_cur;
grid_cur_log=grid_idx_cur;
pos_next_log=pos_next;
grid_next_log=grid_idx_next;
sdf_log= Vector3f(sdf_cur, sdf_next, sdf);
return sdf;
}
bool MpmCore::getSDFNormal(Vector3f& pos, Vector3f& out_sdf_normal)
{
Vector3f vco_log;
Vector3f pos_cur_log;
Vector3f grid_cur_log;
Vector3f pos_next_log;
Vector3f grid_next_log;
Vector3f sdf_log;
float sdf = getSDFPhai_interploted(pos, 0, vco_log, pos_cur_log, grid_cur_log,
pos_next_log, grid_next_log, sdf_log);
if(sdf>=0)
return false;
Vector3f vco_log1;
Vector3f pos_cur_log1;
Vector3f grid_cur_log1;
Vector3f pos_next_log1;
Vector3f grid_next_log1;
Vector3f sdf_log1;
Vector3f pos_dx = pos - Vector3f(grid->grid_size[0], 0, 0);
Vector3f pos_dy = pos - Vector3f(0, grid->grid_size[1], 0);
Vector3f pos_dz = pos - Vector3f(0, 0, grid->grid_size[2]);
out_sdf_normal[0]=-(getSDFPhai_interploted(pos_dx, 0,vco_log1, pos_cur_log1, grid_cur_log1,
pos_next_log1, grid_next_log1, sdf_log1)-sdf);
out_sdf_normal[1]=-(getSDFPhai_interploted(pos_dy, 0,vco_log1, pos_cur_log1, grid_cur_log1,
pos_next_log1, grid_next_log1, sdf_log1)-sdf);
out_sdf_normal[2]=-(getSDFPhai_interploted(pos_dz, 0,vco_log1, pos_cur_log1, grid_cur_log1,
pos_next_log1, grid_next_log1, sdf_log1)-sdf);
if(out_sdf_normal.norm()<=max(abs(sdf_log[1]-sdf_log[0])*(1-ctrl_params.iteplote),0.0001f))
return false;
out_sdf_normal.normalize();
return true;
}
/*
bool MpmCore::getSDFNormal( Vector3f& pos, Vector3f& out_sdf_normal )
{
Vector3i grid_idx = ((pos - grid->grid_min).cwiseQuotient(grid->grid_size)).cast<int>();
const int idxX = grid_idx[0];
const int idxY = grid_idx[1];
const int idxZ = grid_idx[2];
GridNode* cell = grid->getNode(idxX, idxY, idxZ);
if(cell->collision_sdf<0)
return false;
out_sdf_normal[0]=grid->getNode(idxX-1,idxY,idxZ)->collision_sdf - grid->getNode(idxX+1,idxY,idxZ)->collision_sdf;
out_sdf_normal[1]=grid->getNode(idxX,idxY-1,idxZ)->collision_sdf - grid->getNode(idxX,idxY+1,idxZ)->collision_sdf;
out_sdf_normal[2]=grid->getNode(idxX,idxY,idxZ-1)->collision_sdf - grid->getNode(idxX,idxY,idxZ+1)->collision_sdf;
if(out_sdf_normal.norm()<=0.00000001)
return false;
out_sdf_normal.normalize();
return true;
}*/
bool MpmCore::getSDFNormal_box( Vector3f& grid_idx_new, Vector3f& out_sdf_normal )
{
out_sdf_normal= Vector3f(0,0,0);
if(grid_idx_new[0]>=grid->grid_division[0]-grid->boundary)
out_sdf_normal[0]=-1;
if(grid_idx_new[0]<grid->boundary)
out_sdf_normal[0]=1;
if(grid_idx_new[1]>=grid->grid_division[1]-grid->boundary)
out_sdf_normal[1]=-1;
if(grid_idx_new[1]<grid->boundary)
out_sdf_normal[1]=1;
if(grid_idx_new[2]>=grid->grid_division[2]-grid->boundary)
out_sdf_normal[2]=-1;
if(grid_idx_new[2]<grid->boundary)
out_sdf_normal[2]=1;
if(out_sdf_normal.norm()<=0.00000001)
return false;
out_sdf_normal.normalize();
return true;
}
bool MpmCore::updateVelocityWithSolvingCollision( Vector3f& collider_velocity, Vector3f& grid_velocity, Vector3f& sdf_normal, Vector3f& out_velocity )
{
Vector3f v_rel=grid_velocity-collider_velocity;
float vn=v_rel.dot(sdf_normal);
if(vn>=0)
return false;
out_velocity=v_rel-sdf_normal*vn;
float stickness=vn*ctrl_params.frictionCoeff;
float out_v_length=out_velocity.norm();
if(out_v_length<=-stickness)
out_velocity=collider_velocity;//stick
else
out_velocity=out_velocity+out_velocity*stickness/out_v_length+collider_velocity;//friction
return true;
}
void MpmCore::solve_grid_collision()
{
for(int x=1;x<grid->grids.shape()[0]-1;x++)
for(int y=1;y<grid->grids.shape()[1]-1;y++)
for(int z=1;z<grid->grids.shape()[2]-1;z++)
{
GridNode* cell = grid->getNode(x,y,z);
if(!cell->active)
continue;
Vector3i index(x,y,z);
/*
Vector3f sdf_normal;
if(getSDFNormal(index,sdf_normal))
{
Vector3f updated_v;
if( updateVelocityWithSolvingCollision( cell->collision_velocity, cell->velocity_new, sdf_normal, updated_v) )
{
cell->velocity_new=updated_v;
}
}*/
//velocity of collider
Vector3f vco= (1-ctrl_params.iteplote) * cell->collision_velocity_prev
+ ctrl_params.iteplote * cell->collision_velocity;
Vector3f sdf_normal;
Vector3f grid_pos= grid->grid_min + grid->grid_size.cwiseProduct(Vector3f(x,y,z));// * index;
if(getSDFNormal(grid_pos,sdf_normal))
{
Vector3f updated_v;
if( updateVelocityWithSolvingCollision( vco, cell->velocity_new, sdf_normal, updated_v) )
{
cell->velocity_new = updated_v;
}
}
}
}
void MpmCore::compute_deformation_gradient_F()
{
for(int pit=0;pit<particles.size();pit++)
{
Particle* ptcl = &particles[pit];
Vector3f p_grid_index_f = ptcl->getGridIdx(grid->grid_min,grid->grid_size);
Vector3i p_grid_index_i = ptcl->getGridIdx_int(grid->grid_min,grid->grid_size);
Matrix3f velocity_gradient;
velocity_gradient.setZero();
for(int z=-2; z<=2;z++)
{
for(int y=-2; y<=2;y++)
{
for(int x=-2; x<=2;x++)
{
Vector3i index=p_grid_index_i+Vector3i(x,y,z);
if(inGrid(index, grid->grid_division))
{
Vector3f xp=(ptcl->position - grid->grid_size.cwiseProduct(Vector3f(index[0],index[1],index[2]))-grid->grid_min).cwiseQuotient(grid->grid_size);
Vector3f gradient_weight=weight_gradientF(xp);
//fomular in step 4
velocity_gradient+=Eigen::Vector3f(grid->getNode(index[0],index[1],index[2])->velocity_new)*
Eigen::Vector3f(gradient_weight).transpose();
}
}
}
}
//fomular 11
Eigen::Matrix3f Fe_new=(Eigen::Matrix3f::Identity()+velocity_gradient*ctrl_params.deltaT)*ptcl->Fe;
Eigen::Matrix3f F_new=Fe_new*ptcl->Fp;
Eigen::JacobiSVD<Eigen::Matrix3f> svd(Fe_new, Eigen::ComputeFullV | Eigen::ComputeFullU);
Matrix3f clamped_S;
clamped_S.setZero();
clamped_S(0,0)=clamp(svd.singularValues()(0), 1-ctrl_params.critical_compression, 1+ ctrl_params.critical_stretch);
clamped_S(1,1)=clamp(svd.singularValues()(1), 1-ctrl_params.critical_compression, 1+ ctrl_params.critical_stretch);
clamped_S(2,2)=clamp(svd.singularValues()(2), 1-ctrl_params.critical_compression, 1+ ctrl_params.critical_stretch);
Matrix3f clamped_S_inv;
clamped_S_inv.setZero();
clamped_S_inv(0,0)=1/clamped_S(0,0);
clamped_S_inv(1,1)=1/clamped_S(1,1);
clamped_S_inv(2,2)=1/clamped_S(2,2);
Eigen::Matrix3f U=svd.matrixU();
Eigen::Matrix3f V=svd.matrixV();
//fomular 12
ptcl->Fe = U*clamped_S *V.transpose();
ptcl->Fp = V*clamped_S_inv*U.transpose()*F_new;
}
}
void MpmCore::parallel_compute_deformation_gradient_F()
{
tbb::parallel_for(tbb::blocked_range<int>(0, particles.size(), 2500), [&](tbb::blocked_range<int>& r)
{
for(int pit = r.begin(); pit != r.end(); pit++)
{
Particle* ptcl = &particles[pit];
Vector3f p_grid_index_f = ptcl->getGridIdx(grid->grid_min,grid->grid_size);
Vector3i p_grid_index_i = ptcl->getGridIdx_int(grid->grid_min,grid->grid_size);
Matrix3d velocity_gradient;
velocity_gradient.setZero();
for(int z=-2; z<=2;z++)
{
for(int y=-2; y<=2;y++)
{
for(int x=-2; x<=2;x++)
{
Vector3i index=p_grid_index_i+Vector3i(x,y,z);
if(inGrid(index, grid->grid_division))
{
Vector3f xp=(ptcl->position - grid->grid_size.cwiseProduct(Vector3f(index[0],index[1],index[2]))-grid->grid_min).cwiseQuotient(grid->grid_size);
Vector3d gradient_weight = weight_gradientF(xp).cast<double>();
//fomular in step 4
GridNode* node = grid->getNode(index[0], index[1], index[2]);
velocity_gradient += node->velocity_new.cast<double>()*
gradient_weight.transpose();
}
}
}
}
//fomular 11
Eigen::Matrix3d Fe_new = (Eigen::Matrix3d::Identity()+velocity_gradient*ctrl_params.deltaT)* ptcl->Fe.cast<double>();
Eigen::Matrix3d F_new = Fe_new * ptcl->Fp.cast<double>();
Eigen::JacobiSVD<Eigen::Matrix3d> svd(Fe_new, Eigen::ComputeFullV | Eigen::ComputeFullU);
Matrix3d clamped_S;
clamped_S.setZero();
clamped_S(0,0)=clamp(svd.singularValues()(0), 1.0-ctrl_params.critical_compression, 1.0+ ctrl_params.critical_stretch);
clamped_S(1,1)=clamp(svd.singularValues()(1), 1.0-ctrl_params.critical_compression, 1.0+ ctrl_params.critical_stretch);
clamped_S(2,2)=clamp(svd.singularValues()(2), 1.0-ctrl_params.critical_compression, 1.0+ ctrl_params.critical_stretch);
Matrix3d clamped_S_inv;
clamped_S_inv.setZero();
clamped_S_inv(0,0)=1/clamped_S(0,0);
clamped_S_inv(1,1)=1/clamped_S(1,1);
clamped_S_inv(2,2)=1/clamped_S(2,2);
Eigen::Matrix3d U=svd.matrixU();
Eigen::Matrix3d V=svd.matrixV();
//fomular 12
ptcl->Fe = (U*clamped_S *V.transpose()).cast<float>();
ptcl->Fp = (V*clamped_S_inv*U.transpose()*F_new).cast<float>();
}
});
}
void MpmCore::parallel_from_grid_to_particle()
{
tbb::parallel_for(tbb::blocked_range<int>(0, particles.size(), 2500), [&](tbb::blocked_range<int>& r)
{
for(int pit = r.begin(); pit != r.end(); pit++)
{
Particle* ptcl = &particles[pit];
if(!ptcl->isValid)
continue;
//Vector3f p_grid_index_f=particles[pit]->getGridIdx(grid->grid_center,grid->grid_size);
Vector3i p_grid_index_i= ptcl->getGridIdx_int(grid->grid_min,grid->grid_size);
Vector3f v_PIC(0,0,0);
Vector3f v_FLIP= ptcl->velocity;
//Matrix3f cauchyStress=cauchy_stress(particles[pit]->Fe, particles[pit]->Fp)*particles[pit]->volume*-1;
for(int z=-2; z<=2;z++)
{
for(int y=-2; y<=2;y++)
{
for(int x=-2; x<=2;x++)
{
Vector3i index=p_grid_index_i+Vector3i(x,y,z);
if(inGrid(index, grid->grid_division))
{
GridNode* pCell = grid->getNode(index[0], index[1], index[2]);
Vector3f xp=(ptcl->position-grid->grid_size.cwiseProduct(Vector3f(index[0],index[1],index[2]))-grid->grid_min).cwiseQuotient(grid->grid_size);
float weight_p=weight(xp);
v_PIC += pCell->velocity_new*weight_p;
v_FLIP += (pCell->velocity_new - pCell->velocity_old)*weight_p;
}
}
}
}
ptcl->velocity=v_PIC*(1-ctrl_params.flip_percent)+v_FLIP*ctrl_params.flip_percent;
if(pit==0)
cout<<"vel:"<<ptcl->velocity[0]<<" "<<ptcl->velocity[1]<<" "<<ptcl->velocity[2]<<endl;
}
});
}
void MpmCore::from_grid_to_particle()
{
for(int pit=0;pit<particles.size();pit++)
{
Particle* ptcl = &particles[pit];
if(!ptcl->isValid)
continue;
//Vector3f p_grid_index_f=particles[pit]->getGridIdx(grid->grid_center,grid->grid_size);
Vector3i p_grid_index_i= ptcl->getGridIdx_int(grid->grid_min,grid->grid_size);
Vector3f v_PIC(0,0,0);
Vector3f v_FLIP= ptcl->velocity;
//Matrix3f cauchyStress=cauchy_stress(particles[pit]->Fe, particles[pit]->Fp)*particles[pit]->volume*-1;
for(int z=-2; z<=2;z++)
{
for(int y=-2; y<=2;y++)
{
for(int x=-2; x<=2;x++)
{
Vector3i index=p_grid_index_i+Vector3i(x,y,z);
if(inGrid(index, grid->grid_division))
{
GridNode* pCell = grid->getNode(index[0], index[1], index[2]);// grid->grids[index[0]][index[1]][index[2]];
Vector3f xp=(ptcl->position-grid->grid_size.cwiseProduct(Vector3f(index[0],index[1],index[2]))-grid->grid_min).cwiseQuotient(grid->grid_size);
float weight_p=weight(xp);
v_PIC += pCell->velocity_new*weight_p;
v_FLIP += (pCell->velocity_new - pCell->velocity_old)*weight_p;
}
}
}
}
ptcl->velocity=v_PIC*(1-ctrl_params.flip_percent)+v_FLIP*ctrl_params.flip_percent;
if(pit==0)
cout<<"vel:"<<ptcl->velocity[0]<<" "<<ptcl->velocity[1]<<" "<<ptcl->velocity[2]<<endl;
}
}
/*
void MpmCore::solve_particle_collision()
{
for(int pit=0;pit<particles.size();pit++)
{
Particle* ptcl = &particles[pit];
if(!ptcl->isValid)
continue;
Vector3f p_grid_index_f= ptcl->getGridIdx(grid->grid_min,grid->grid_size);
Vector3i p_grid_index_i= ptcl->getGridIdx_int(grid->grid_min,grid->grid_size);
Vector3f p_grid_index_i_new=(ptcl->position+ptcl->velocity*ctrl_params.deltaT-grid->grid_min).cwiseQuotient(grid->grid_size);
Vector3i index_check_1=p_grid_index_i-Vector3i(1,1,1);
Vector3i index_check_2=p_grid_index_i+Vector3i(1,1,1);
if(!inGrid(p_grid_index_i,grid->grid_division)||!inGrid(index_check_1,grid->grid_division)||!inGrid(index_check_2,grid->grid_division))
{
ptcl->isValid=false;
continue;
}
float sdf=0;
Vector3f sdf_normal;
Vector3f velocity_collider(0,0,0);
for(int z=p_grid_index_i.z(); z<=p_grid_index_i.z()+1;z++)
{
for(int y=p_grid_index_i.y(); y<=p_grid_index_i.y()+1;y++)
{
for(int x=p_grid_index_i.x(); x<=p_grid_index_i.x()+1;x++)
{
float weight_sdf=fabs( ( p_grid_index_f.z()-z)*
( p_grid_index_f.y()-y)*
( p_grid_index_f.x()-x) );
Vector3i index(x,y,z);
Vector3i index_check_1=Vector3i(x-1,y-1,z-1);
Vector3i index_check_2=Vector3i(x+1,y+1,z+1);
if(inGrid(index, grid->grid_division)&&inGrid(index_check_1,grid->grid_division)&&inGrid(index_check_2,grid->grid_division))
{
Vector3f temp_normal;
getSDFNormal(index,temp_normal);
sdf_normal+=temp_normal*weight_sdf;
GridNode* cell = grid->getNode(index[0], index[1], index[2]);
sdf+=cell->collision_sdf*weight_sdf;
velocity_collider+= cell->collision_velocity*weight_sdf;
}
}
}
}
//if(getSDFNormal_box(p_grid_index_i_new,sdf_normal))
if(sdf>0)
{
Vector3f updated_v;
sdf_normal.normalize();
if( updateVelocityWithSolvingCollision( velocity_collider, ptcl->velocity, sdf_normal, updated_v) )
{
ptcl->velocity=updated_v;
}
}
}
}*/
//step 9 handle particle collision
void MpmCore::solve_particle_collision()
{
for(int pit=0;pit<particles.size();pit++)
{
Particle* ptcl = &particles[pit];
if(!ptcl->isValid)
continue;
Vector3f p_grid_index_f = ptcl->getGridIdx(grid->grid_min, grid->grid_size);
Vector3i p_grid_index_i = ptcl->getGridIdx_int(grid->grid_min,grid->grid_size);
Vector3i index_check_1=p_grid_index_i-Vector3i(1,1,1);
Vector3i index_check_2=p_grid_index_i+Vector3i(1,1,1);
if(!inGrid(p_grid_index_i,grid->grid_division)||!inGrid(index_check_1,grid->grid_division)||!inGrid(index_check_2, grid->grid_division))
{
ptcl->isValid=false;
continue;
}
Vector3f p_grid_index_i_new=(ptcl->position + ptcl->velocity * ctrl_params.deltaT - grid->grid_min).cwiseQuotient(grid->grid_size);
float sdf=0;
Vector3f sdf_normal;
//velocity of collider
GridNode* cell = grid->getNode(p_grid_index_i[0], p_grid_index_i[1], p_grid_index_i[2]);
Vector3f vco= (1-ctrl_params.iteplote) * cell->collision_velocity_prev
+ ctrl_params.iteplote * cell->collision_velocity;
if(getSDFNormal(ptcl->position,sdf_normal))
//if(getSDFNormal_box(p_grid_index_i_new,sdf_normal))
//if(sdf>0)
{
Vector3f updated_v;
sdf_normal.normalize();
if( updateVelocityWithSolvingCollision( vco, ptcl->velocity, sdf_normal, updated_v) )
{
ptcl->velocity=updated_v;
}
}
}
}
void MpmCore::update_position()
{
for(int pit=0;pit<particles.size();pit++)
{
Particle* ptcl = &particles[pit];
ptcl->position+= ptcl->velocity*ctrl_params.deltaT;
}
}
bool MpmCore::step(int ithFrame, float deltaTime, int nSubstep)
{
// 更新粒子位置
const MpmStatus* status = m_recorder.getStatusPtr(ithFrame-1);
bool res = true;
if (status)
{
res &= status->copy(particles);
res &= status->copyGrid(grid);
}
if (!res)
{
return false;
}
initTimer();
int msArray[8] = {0,0,0,0, 0,0,0,0};
ctrl_params.deltaT = deltaTime / nSubstep;
ctrl_params.maya_deltaT = deltaTime;
PRINT_F("delta time %f, maya %f", ctrl_params.deltaT, ctrl_params.maya_deltaT);
for (int ithStep = 0; ithStep < nSubstep; ++ithStep)
{
ctrl_params.iteplote = (float)(ithStep + 1.f) / (float)nSubstep;
if(ctrl_params.frame!=0)
{
//from_particles_to_grid();
parallel_from_particles_to_grid();
msArray[0] += getDeltaTime();
}
if(ctrl_params.frame==0)
{
// init_particle_volume_velocity();
// msArray[1] += getDeltaTime();
}
compute_grid_velocity();
msArray[2] += getDeltaTime();
solve_grid_collision();
msArray[3] += getDeltaTime();
parallel_compute_deformation_gradient_F();
msArray[4] += getDeltaTime();
parallel_from_grid_to_particle();
msArray[5] += getDeltaTime();
solve_particle_collision();
msArray[6] += getDeltaTime();
update_position();
msArray[7] += getDeltaTime();
ctrl_params.frame++;
}
PRINT_F("from_particles_to_grid: %f", float(msArray[0])/CLOCKS_PER_SEC);
PRINT_F("init_particle_volume_velocity: %f", float(msArray[1])/CLOCKS_PER_SEC);
PRINT_F("compute_grid_velocity: %f", float(msArray[2])/CLOCKS_PER_SEC);
PRINT_F("solve_grid_collision: %f", float(msArray[3])/CLOCKS_PER_SEC);
PRINT_F("compute_deformation_gradient: %f", float(msArray[4])/CLOCKS_PER_SEC);
PRINT_F("from_grid_to_particle: %f", float(msArray[5])/CLOCKS_PER_SEC);
PRINT_F("solve_particle_collision: %f", float(msArray[6])/CLOCKS_PER_SEC);
PRINT_F("update_position: %f", float(msArray[7])/CLOCKS_PER_SEC);
// 将模拟结果记下来
m_recorder.addStatus(ithFrame, MpmStatus(particles, m_worldMatList, grid));
return true;
}
void MpmCore::createGrid(const Vector3f& gridMin,
const Vector3f& gridMax,
const Vector3f& gridCellSize,
int boundary)
{
PRINT_F("boundary %d", boundary);
Vector3i gridDimClamp = (gridMax-gridMin).cwiseQuotient(gridCellSize).cwiseMax(Vector3f(5,5,5)).cast<int>();
Vector3f cellSize = (gridMax - gridMin).cwiseQuotient(gridDimClamp.cast<float>());
grid = new GridField(cellSize, gridMin, gridDimClamp, boundary);
const int bId[3][2] = {
{boundary, gridDimClamp[0]-1-boundary},
{boundary, gridDimClamp[1]-1-boundary},
{boundary, gridDimClamp[2]-1-boundary},
};
float depth[3];
for (int i = 0; i < gridDimClamp[0]; ++i)
{
depth[0] = min(i-bId[0][0],bId[0][1]-i) * cellSize[0];
for (int j = 0; j < gridDimClamp[1]; ++j)
{
depth[1] = min(j-bId[1][0],bId[1][1]-j) * cellSize[1];
for (int k =0; k < gridDimClamp[2]; ++k)
{
depth[2] = min(k-bId[2][0],bId[2][1]-k) * cellSize[2];
float d = min(min(depth[0], depth[1]), depth[2]);
if (d > 0)
{
continue;
}
GridNode* cell = grid->getNode(i,j,k);
cell->collision_sdf= d;
cell->collision_sdf_prev= d;
cell->collision_velocity.setZero();
cell->collision_velocity_prev.setZero();
//PRINT_F("depth %d %d %d, %f", i,j,k,grid->grids[i][j][k]->collision_sdf);
}
}
}
}
void MpmCore::create_grid()
{