/// <summary>
/// velocity verlet routine to propagate the particle ensemble
/// </summary>
/// <param name="Height"></param>
/// <param name="Width"></param>
/// <param name="pExternalField"></param>
public void VelocityVerletPropagation(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 < NumberOfForceFieldObjects; ++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;
// increment ParticleEnsemble Private data member step
++step;
if (BerendsenThermostat)
{
// Berendsen Thermostat
BerendsenVelocityRescaling();
}
// this loop uses verlet scheme (VV) to propagate the positions forward one step
for (i = 0; i < NumberOfParticles; ++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;
if (pxnew > GetParticleRadius(i) && pxnew < (BoxWidth - GetParticleRadius(i)))
{
// this the standard VV code here
SetXParticlePosition(i, pxnew);
}
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);
}
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);
}
Particles[i].GridSector.GetSector(Particles[i].Position);
}
// check whether all the positions are changed from the last step
for (i = 0; i < NumberOfParticles; ++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,
// adjust particle positions to eliminate overlap - this can cause the sim to freeze
EliminateParticleOverlap(BoxHeight, BoxWidth);
for (i = 0; i < NumberOfParticles; ++i)
{
// then we zero out the forces and velocities & repropagate the positions
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);
Particles[i].GridSector.GetSector(Particles[i].Position);
}
AllPositionsUnchangedFromLastStep = false;
}
UpdateInterParticleSeparations();
if (pExternalField != null)
{
pExternalField.CalculateForceField(this);
}
if (GetForceFieldObject(0).ForceFieldType == "HardSphereForceField")
{
GetForceFieldObject(0).CalculateForceField(this);
}
else
{
for (i = 0; i < NumberOfParticles; ++i)
{
// save the present forces to t-1 vectors
SetLastXParticleForce(i, GetXParticleForce(i));
SetLastYParticleForce(i, GetYParticleForce(i));
}
// zero out the force vectors & potential energy
ZeroXForces();
ZeroYForces();
PotentialEnergy = 0.0;
for (kk = 0; kk < NumberOfForceFieldObjects; ++kk)
{
// calculate & set the forces at the new positions
GetForceFieldObject(kk).CalculateForceField(this);
}
for (i = 0; i < NumberOfParticles; ++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);
}
// Update the ensemble velocity autocorrelation function
//if (m_FFTenabled)
//{
// UpdateVelocityAutoCorrelationFunction();
// FFTVelocityAutoCorrelationFunction();
//}
// see whether any collisions occurred
DetermineIfCollisionsOccurred();
}
}
}
public static void LoadConfig(string filename)
{
#region Load the actual config
if (File.Exists(filename))
{
RC.WriteLine(ConsoleThemeColor.TitleText1, "Loading config '" + filename + "'");
XmlDocument doc = new XmlDocument();
doc.Load(filename);
m_Options.Load(doc.DocumentElement);
}
#endregion
#region Setup The Field Image
m_CompositeFieldImage.Bounds = m_Options.Kinect.Bounds;
int i = 0;
foreach (DS.Simulation.CompositeFieldImage.KinectFieldImage field in m_CompositeFieldImage.Images)
{
field.X = m_Options.Kinect.Cameras[i].X;
field.Y = m_Options.Kinect.Cameras[i++].Y;
}
#endregion
#region Setup The Particle Simulation
double gradScaleFactor = 1000.0;
double MinRad = 10.0;
double MaxRad = 30.0;
List<string> FFtype = new List<string>(new string[] { "SoftSpheres", "ExternalField" });
ParticleStaticObjects.AtomPropertiesDefinition.Clear();
ParticleStaticObjects.AtomPropertiesDefinition.AddParticleDefinition("A", 1, new Color3(0.0390625f, 0.1953125f, 0.99609375f), 0, 20); // neon blue 0xc00A32FF
ParticleStaticObjects.AtomPropertiesDefinition.AddParticleDefinition("B", 4, new Color3(1f, 0.03921569f, 0.1960784f), 1, 49); // red 0xc0FF0A32
ParticleStaticObjects.AtomPropertiesDefinition.AddParticleDefinition("C", 6, new Color3(0.1960784f, 0.03921569f, 1f), 2, 45); // purple 0xc0320AFF
ParticleStaticObjects.AtomPropertiesDefinition.AddParticleDefinition("D", 9.2, new Color3(0.1490196f, 0.8470589f, 1f), 3, 43); // sky blue 0xc026D8FF // 0xc032FF0A, 3, 43); // green
ParticleStaticObjects.AtomPropertiesDefinition.AddParticleDefinition("E", 12.6, new Color3(1f, 0.1960784f, 0.03921569f), 4, 38); // orange 0xc0FF320A
ParticleStaticObjects.ReSeedRandom(42);
m_Ensemble = new ParticleEnsemble(1, MinRad, MaxRad, FFtype, ArtworkStaticObjects.CompositeFieldImage.Height, ArtworkStaticObjects.CompositeFieldImage.Width, gradScaleFactor);
m_ExternalField = new ExternalField(m_Ensemble, ArtworkStaticObjects.CompositeFieldImage);
for (int j = 0; j < ParticleStaticObjects.AtomPropertiesDefinition.Count; j++)
{
ParticleStaticObjects.AtomPropertiesDefinition.SetAttractiveOrRepulsive(j, Options.Simulation.ParticleTypes[j].AttractiveOrRepulsive);
ParticleStaticObjects.AtomPropertiesDefinition.SetEnabled(j, Options.Simulation.ParticleTypes[j].IsEnabled);
ParticleStaticObjects.AtomPropertiesDefinition.SetSound(j, Options.Simulation.ParticleTypes[j].IsSoundOn);
}
m_Ensemble.BerendsenThermostatCoupling = Options.Simulation.BerendsenThermostatCoupling;
m_Ensemble.EquilibriumTemperature = Options.Simulation.EquilibriumTemperature;
m_Ensemble.GradientScaleFactor = Options.Simulation.GradientScaleFactor;
int newNumber = Options.Simulation.NumberOfParticles;
while (ArtworkStaticObjects.Ensemble.NumberOfParticles < newNumber)
{
ArtworkStaticObjects.Ensemble.InitializeOneNewParticle();
}
while (ArtworkStaticObjects.Ensemble.NumberOfParticles > newNumber)
{
ArtworkStaticObjects.Ensemble.Particles.Pop();
}
m_Ensemble.ParticleScale = Options.Simulation.ParticleScale;
m_Ensemble.PotentialEnergy = Options.Simulation.PotentialEnergy;
//ParticleStaticObjects.AtomPropertiesDefinition.ToggleAttractiveOrRepulsive(0);
#endregion
}
