private void InitializePlasticity()
{
_isPlasticityInitialized = true;
_springs.Clear();
foreach (Particle pa in Particles)
{
foreach (Particle pb in Particles)
{
if (pa.GetHashCode() == pb.GetHashCode())
{
continue;
}
float q = pa.Position.dst(pb.Position);
_rij.Set(pb.Position);
_rij.Sub(pa.Position);
_rij.mul(1 / q);
if (q < RestLength)
{
_springs.Add(new Spring2(pa, pb, q));
}
}
pa.Velocity.Set(0, 0);
}
}
private void ApplyViscosity(float deltaTime)
{
for (int i = 0; i < Particles.Count; i++)
{
Particle particle = Particles[i];
_tempParticles = Particles.GetNearby(particle);
int len2 = _tempParticles.Count;
if (len2 > MaxNeighbors)
{
len2 = MaxNeighbors;
}
for (int j = 0; j < len2; j++)
{
Particle tempParticle = _tempParticles[j];
float q = particle.Position.dst2(tempParticle.Position);
if ((q < InfluenceRadiusSquared) && (q != 0))
{
q = (float)Math.Sqrt(q);
_rij.Set(tempParticle.Position);
_rij.Sub(particle.Position);
_rij.mul(1 / q);
q /= InfluenceRadius;
_tempVect.Set(particle.Velocity);
_tempVect.Sub(tempParticle.Velocity);
float u = _tempVect.dot(_rij);
if (u <= 0.0f)
{
continue;
}
float I = (deltaTime * (1 - q) * (ViscositySigma * u + ViscosityBeta * u * u));
_rij.mul(I * 0.5f);
_tempVect.Set(particle.Velocity);
_tempVect.Sub(_rij);
particle.Velocity.Set(_tempVect);
_tempVect.Set(tempParticle.Velocity);
_tempVect.add(_rij);
tempParticle.Velocity.Set(_tempVect);
}
}
}
}
private void DoubleDensityRelaxation()
{
for (int i = 0; i < Particles.Count; i++)
{
Particle particle = Particles[i];
particle.Density = 0;
particle.NearDensity = 0;
_tempParticles = Particles.GetNearby(particle);
int len2 = _tempParticles.Count;
if (len2 > MaxNeighbors)
{
len2 = MaxNeighbors;
}
for (int j = 0; j < len2; j++)
{
Particle tempParticle = _tempParticles[j];
float q = particle.Position.dst2(tempParticle.Position);
if (q < InfluenceRadiusSquared && q != 0)
{
q = (float)Math.Sqrt(q);
q /= InfluenceRadius;
float qq = ((1 - q) * (1 - q));
particle.Density += qq;
particle.NearDensity += qq * (1 - q);
}
}
particle.Pressure = (Stiffness * (particle.Density - DensityRest));
particle.NearPressure = (StiffnessNear * particle.NearDensity);
_dx.Set(0.0f, 0.0f);
for (int j = 0; j < len2; j++)
{
Particle tempParticle = _tempParticles[j];
float q = particle.Position.dst2(tempParticle.Position);
if ((q < InfluenceRadiusSquared) && (q != 0))
{
q = (float)Math.Sqrt(q);
_rij.Set(tempParticle.Position);
_rij.Sub(particle.Position);
_rij.mul(1 / q);
q /= InfluenceRadius;
float D = (_deltaTime2 * (particle.Pressure * (1 - q) + particle.NearPressure * (1 - q) * (1 - q)));
_rij.mul(D * 0.5f);
tempParticle.Position.Set(tempParticle.Position.X + _rij.X, tempParticle.Position.Y + _rij.Y);
_dx.Sub(_rij);
}
}
particle.Position.Set(particle.Position.add(_dx));
}
}
