private void SetupForTesting(int Nparticles)
{
double gradScaleFactor = 3000.0;
double MinRad = 40.0;
double MaxRad = 50.0;
List<string> FFtype = new List<string>(new string[] { "SoftSpheres", "ExternalField" });
ParticleStaticObjects.AtomPropertiesDefinition.Clear();
ParticleStaticObjects.AtomPropertiesDefinition.addParticleDefinition(2, unchecked((int)0xc00A32FF), 0, 50); // neon blue
ParticleStaticObjects.AtomPropertiesDefinition.addParticleDefinition(4, unchecked((int)0xc0FF0A32), 1, 49); // red
ParticleStaticObjects.AtomPropertiesDefinition.addParticleDefinition(6, unchecked((int)0xc0320AFF), 2, 45); // purple
ParticleStaticObjects.AtomPropertiesDefinition.addParticleDefinition(9.2, unchecked((int)0xc026D8FF), 3, 43); // sky blue // 0xc032FF0A, 3, 43); // green
ParticleStaticObjects.AtomPropertiesDefinition.addParticleDefinition(12.6, unchecked((int)0xc0FF320A), 4, 38); // orange
ParticleStaticObjects.ReSeedRandom(42);
Ensemble1 = new ParticleEnsemble(Nparticles, MinRad, MaxRad, FFtype, m_SizeY, m_SizeX, gradScaleFactor);
Field = new ExternalField(Ensemble1);
double[] background = new double[m_NumberOfPixels];
for (int i = 0; i < m_NumberOfPixels; i++)
{
background[i] = 512;
}
Field.IncrementGrabberCalls(); // increment the number of grabber calls
Field.BackgroundCalibration(m_NumberOfPixels, background); // in order to simply set the background to zero
Field.SetCalibrating(false);
}
/*
// function to propagate the particle ensemble
public void VelocityVerletPropagation(int, int, ExternalField)
{
}
*/
// velocity verlet routine to propagate the particle ensemble
public void VelocityVerletPropagation(int Height, int Width, ExternalField pExternalField)
{
int i, kk;
double V = 0.0, T = 0.0, dt, pxnew, pynew, factor;
AllPositionsUnchangedFromLastStep = true;
BoxWidth = Width;
BoxHeight = Height;
if (NumberOfParticlesChangedFlag)
{
NumberOfParticlesChangedFlag = false;
if (NumberOfParticlesIsGreaterFlag)
{
for (kk = 0; kk < GetNumberOfForceFieldObjects(); ++kk)
{ // calculate the ij energy terms for particle set including the new ones
GetForceFieldObject(kk).UpdateEnergyTerms(this);
}
}
}
else
{
// Timestep = 1.0/(double)ofGetFrameRate();
Timestep = 0.005;
dt = Timestep;
++step; // increment ParticleEnsemble Private data member step
if (BerendsenThermostat)
{ // Berendsen Thermostat
BerendsenVelocityRescaling();
}
// T=GetKineticEnergy();
// V=GetPotentialEnergy(); // get the potential energy - pretty useless when the external field is time dependent - but useful for
// TotalEnergy=T+V; // testing that new interparticle forceFields conserve energy
//this loop uses verlet scheme (VV) to propagate the positions forward one step
for (i = 0; i < GetNumberOfParticles(); ++i)
{
SetLastXParticlePosition(i, GetXParticlePosition(i));
SetLastYParticlePosition(i, GetYParticlePosition(i));
factor = 0.5 * dt * dt / GetParticleMass(i);
pxnew = GetXParticlePosition(i) + GetXParticleVelocity(i) * dt + GetXParticleForce(i) * factor;
pynew = GetYParticlePosition(i) + GetYParticleVelocity(i) * dt + GetYParticleForce(i) * factor;
// cout << "x " << pxnew << " y " << pynew << endl;
if (pxnew > GetParticleRadius(i) && pxnew < (BoxWidth - GetParticleRadius(i)))
{
SetXParticlePosition(i, pxnew); // this the standard VV code here
// AllPositionsUnchangedFromLastStep = false; // this is a stability measure, to detect if the simulation has frozen from frame to frame
}
else
{ // this is to reflect off the walls; added by DRG in lieu of soft walls to improve real time stability... not part of a standard VV scheme
SetXParticlePosition(i, GetLastXParticlePosition(i));
SetXParticleVelocity(i, -1.0 * GetXParticleVelocity(i));
SetWasReflectedByWall(i, true);
calculateParticleVelocitiesInXWallFrame(i);
// cout << "X Wall Reflection, Particle " << i << endl;
}
if (pynew > GetParticleRadius(i) && pynew < (BoxHeight - GetParticleRadius(i)))
{ // this the standard VV code here
SetYParticlePosition(i, pynew);
}
else
{ // this is to reflect off the walls; added by DRG in lieu of soft walls to improve real time stability... not part of a standard VV scheme
SetYParticlePosition(i, GetLastYParticlePosition(i));
SetYParticleVelocity(i, -1.0 * GetYParticleVelocity(i));
SetWasReflectedByWall(i, true);
calculateParticleVelocitiesInYWallFrame(i);
// cout << "Y Wall Reflection, Particle " << i << endl;
}
}
//check whether all the positions are changed from the last step
for (i = 0; i < GetNumberOfParticles(); ++i)
{
if (GetYParticlePosition(i) != GetLastYParticlePosition(i) || GetXParticlePosition(i) != GetLastXParticlePosition(i))
{
AllPositionsUnchangedFromLastStep = false;
}
}
if (AllPositionsUnchangedFromLastStep)
{ // this is a stability measure; if the frame is frozen wrt to the previous frame,
//cout << "Positions unchanged" << endl;
EliminateParticleOverlap(BoxHeight, BoxWidth); // adjust particle positions to eliminate overlap - this can cause the sim to freeze
for (i = 0; i < GetNumberOfParticles(); ++i)
{ // then we zero out the forces and velocities & repropagate the positions
// cout << px[i] << " " << py[i] << " " << vx[i] << " " << vy[i] << " " << fx[i] << " " << fy[i] << " " << fxLast[i] << " " << fyLast[i] << endl;
SetXParticleForce(i, 0.0);
SetYParticleForce(i, 0.0);
SetLastXParticlePosition(i, GetXParticlePosition(i));
SetLastYParticlePosition(i, GetYParticlePosition(i));
SetXParticlePosition(i, GetXParticlePosition(i) + GetXParticleVelocity(i) * dt + (GetXParticleForce(i) / GetParticleMass(i)) * dt * dt * 0.5);
SetYParticlePosition(i, GetYParticlePosition(i) + GetYParticleVelocity(i) * dt + (GetYParticleForce(i) / GetParticleMass(i)) * dt * dt * 0.5);
}
AllPositionsUnchangedFromLastStep = false;
}
UpdateInterParticleSeparations();
if (pExternalField != null)
{
pExternalField.CalculateForceField(this);
}
if (GetForceFieldObject(0).ForceFieldType == "HardSphereForceField")
{
GetForceFieldObject(0).CalculateForceField(this);
}
else
{
for (i = 0; i < GetNumberOfParticles(); ++i)
{ // save the present forces to t-1 vectors
SetLastXParticleForce(i, GetXParticleForce(i));
SetLastYParticleForce(i, GetYParticleForce(i));
}
ZeroXForces(); // zero out the force vectors & potential energy
ZeroYForces();
SetPotentialEnergy(0.0);
for (kk = 0; kk < GetNumberOfForceFieldObjects(); ++kk)
{ // calculate & set the forces at the new positions
GetForceFieldObject(kk).CalculateForceField(this);
}
for (i = 0; i < GetNumberOfParticles(); ++i)
{ // use VV scheme to propagate the velocities forward
factor = dt * 0.5 / GetParticleMass(i);
SetXParticleVelocity(i, GetXParticleVelocity(i) + (GetXParticleForce(i) + GetLastXParticleForce(i)) * factor);
SetYParticleVelocity(i, GetYParticleVelocity(i) + (GetYParticleForce(i) + GetLastYParticleForce(i)) * factor);
}
// see whether any collisions occurred
DetermineIfCollisionsOccurred();
}
}
}
