// streamline advects as far as possible till the boundary or terminates at
// critical points. only two cases will happen: OUT_OF_BOUND & CRITICAL_POINT
int vtCStreamLine::executeInfiniteAdvection(TIME_DIR time_dir,
TIME_DEP time_dep,
vtListSeedTrace& seedTrace,
float& totalStepsize,
vector<float>* vStepsize)
{
int istat;
vtParticleInfo* thisSeed;
PointInfo thisParticle, prevParticle, second_prevParticle, seedInfo;
vtListParticleIter sIter;
float dt, dt_estimate, cell_volume, mag, curTime;
VECTOR3 vel;
INTEG_ORD integ_ord;
// initialize
integ_ord = m_integrationOrder;
sIter = m_lSeeds.begin();
thisSeed = *sIter;
seedInfo = thisSeed->m_pointInfo;
seedTrace.clear();
totalStepsize = 0.0;
// the first point
seedTrace.push_back(new VECTOR3(seedInfo.phyCoord));
istat = m_pField->at_phys(seedInfo.fromCell, seedInfo.phyCoord, seedInfo,
m_fCurrentTime, vel);
if((fabs(vel[0]) < m_fStationaryCutoff) &&
(fabs(vel[1]) < m_fStationaryCutoff) &&
(fabs(vel[2]) < m_fStationaryCutoff))
return CRITICAL_POINT;
thisParticle = seedInfo;
curTime = m_fCurrentTime;
// get the initial stepsize
cell_volume = m_pField->volume_of_cell(seedInfo.inCell);
mag = vel.GetMag();
if(fabs(mag) < 1.0e-6f)
dt_estimate = 1.0e-5f;
else
dt_estimate = pow(cell_volume, (float)0.3333333f) / mag;
dt = m_fInitialStepSize * dt_estimate;
#ifdef DEBUG
fprintf(fDebugOut, "****************new particle*****************\n");
fprintf(fDebugOut, "seed: %f, %f, %f with step size %f\n",
seedInfo.phyCoord[0],seedInfo.phyCoord[1],seedInfo.phyCoord[2],dt);
#endif
// start to advect
while(true)
{
second_prevParticle = prevParticle;
prevParticle = thisParticle;
// take a proper step, also calculates a new step size for the next step
if(integ_ord == SECOND || integ_ord == FOURTH)
istat = oneStepGeometric(integ_ord, time_dir, time_dep,
thisParticle, prevParticle,
second_prevParticle, &curTime, &dt,
seedTrace.size());
else if(integ_ord == RK45)
istat = oneStepEmbedded(integ_ord, time_dir, time_dep,
thisParticle, &curTime, &dt);
else
return OUT_OF_BOUND;
if(istat == OUT_OF_BOUND) // out of boundary
{
// find the boundary intersection point
VECTOR3 intersectP, startP, endP;
float oldStepsize, stepSize;
oldStepsize = stepSize = dt;
startP = prevParticle.phyCoord;
endP = thisParticle.phyCoord;
m_pField->BoundaryIntersection(intersectP, startP, endP, &stepSize,
oldStepsize);
totalStepsize += stepSize;
seedTrace.push_back(new VECTOR3(intersectP));
if(vStepsize != NULL)
vStepsize->push_back(stepSize);
return OUT_OF_BOUND;
}
// find the loop
list<VECTOR3*>::iterator searchIter;
searchIter = seedTrace.end();
searchIter--;
for(; searchIter != seedTrace.begin(); searchIter--)
{
if(thisParticle.phyCoord == **searchIter) // loop
return CRITICAL_POINT;
}
m_pField->at_phys(thisParticle.fromCell, thisParticle.phyCoord,
thisParticle, m_fCurrentTime, vel);
seedTrace.push_back(new VECTOR3(thisParticle.phyCoord));
if(vStepsize != NULL)
vStepsize->push_back(dt);
totalStepsize += dt;
#ifdef DEBUG
fprintf(fDebugOut, "***************advected particle***************\n");
fprintf(fDebugOut, "pos = (%f, %f, %f), vel = (%f, %f, %f) with step size %f, total step size %f\n", thisParticle.phyCoord[0], thisParticle.phyCoord[1], thisParticle.phyCoord[2], vel[0], vel[1], vel[2], dt, totalStepsize);
#endif
if(totalStepsize > 4000.0)
{
printf("curl\n");
vel.Set(0.0, 0.0, 0.0);
}
if((fabs(vel[0]) < m_fStationaryCutoff) &&
(fabs(vel[1]) < m_fStationaryCutoff) &&
(fabs(vel[2]) < m_fStationaryCutoff))
return CRITICAL_POINT;
if((int)seedTrace.size() > 2)
adapt_step(second_prevParticle.phyCoord, prevParticle.phyCoord,
thisParticle.phyCoord, &dt);
}
return OUT_OF_BOUND;
}
int vtCStreamLine::computeFieldLine(TIME_DIR time_dir,
TIME_DEP time_dep,
vtListSeedTrace& seedTrace,
list<float>& stepList,
PointInfo& seedInfo)
{
int istat;
PointInfo thisParticle;
double dt, cell_vol, mag;
double curTime;
VECTOR3 vel;
float totalStepsize = 0.0;
bool onAdaptive = true;
int nSetAdaptiveCount = 0;
// the first particle
thisParticle = seedInfo;
seedTrace.push_back(new VECTOR3(seedInfo.phyCoord));
curTime = (double)m_fCurrentTime;
istat = m_pField->getFieldValue(seedInfo.phyCoord, m_fCurrentTime, vel);
if(istat == OUT_OF_BOUND)
return OUT_OF_BOUND; // the advection is out of boundary
if(istat == MISSING_VALUE ||((abs(vel[0]) < m_fStationaryCutoff) && (abs(vel[1]) < m_fStationaryCutoff) && (abs(vel[2]) < m_fStationaryCutoff)))
return CRITICAL_POINT; // this is critical point
// get the initial step size
cell_vol = m_pField->GetMinCellVolume();
mag = vel.GetDMag();
dt = m_fInitStepSize * cell_vol / mag;
//Determine the value of mag*dt to project 10 times init size.
double maxMagDt = 10.*dt*mag;
int rollbackCount = 0;
// start to advect
while(totalStepsize < (float)((m_nMaxsize-1)*m_fSamplingRate))
{
bool doingRetrace = false;
int retrace = true;
while(retrace)
{
retrace = false;
for(int magTry = 0; magTry < 40; magTry++) {
istat = runge_kutta4(time_dir, time_dep, thisParticle, &curTime, dt, maxMagDt);
if (istat != FIELD_TOO_BIG) break;
//Shrink dt by factor of 10.
dt = 0.1*dt;
}
assert (istat != FIELD_TOO_BIG);
seedTrace.push_back(new VECTOR3(thisParticle.phyCoord));
stepList.push_back(dt);
if(istat == OUT_OF_BOUND) // out of boundary
return OUT_OF_BOUND;
m_pField->getFieldValue(thisParticle.phyCoord, m_fCurrentTime, vel);
if((abs(vel[0]) < m_fStationaryCutoff) && (abs(vel[1]) < m_fStationaryCutoff) && (abs(vel[2]) < m_fStationaryCutoff))
return CRITICAL_POINT;
totalStepsize += dt; // accumulation of step size
nSetAdaptiveCount++;
if((nSetAdaptiveCount == 2) && (onAdaptive == false))
onAdaptive = true;
// just generate valid new point
if(((int)seedTrace.size() > 2)&&(onAdaptive))
{
double minStepsize, maxStepsize;
VECTOR3 thisPhy, prevPhy, second_prevPhy;
list<VECTOR3*>::iterator pIter = seedTrace.end();
pIter--;
thisPhy = **pIter;
pIter--;
prevPhy = **pIter;
pIter--;
second_prevPhy = **pIter;
mag = vel.GetDMag();
minStepsize = m_fInitStepSize * cell_vol / mag;
maxStepsize = m_fMaxStepSize * cell_vol / mag;
retrace = adapt_step(second_prevPhy, prevPhy, thisPhy, minStepsize, maxStepsize, &dt, onAdaptive);
if(onAdaptive == false)
nSetAdaptiveCount = 0;
assert (rollbackCount < 10000);//If we got here, it's surely an infinite loop!
// roll back and retrace
//the doingRetrace flag is to stop double retracing (which results in infinite loop!)
//Note a slightly different approach is in VTTimeVaryingFieldLine.cpp
if(retrace && !doingRetrace)
{
seedTrace.pop_back();
seedTrace.pop_back();
thisParticle.Set(*(seedTrace.back()));
totalStepsize -= stepList.back();
stepList.pop_back();
totalStepsize -= stepList.back();
stepList.pop_back();
rollbackCount++;
doingRetrace = true;
} else doingRetrace = false;
}
}// end of retrace
//What was the distance advected?
}// end of advection
return (OKAY);
}
