public void calcViscosityForce(Sphere p)
{
Vector3 f = new Vector3(0, 0, 0);
int[] closePointInds = Game.neighborsIndicesConcatenated(p.Position);
for (int i = 0; i < closePointInds.Length; i++)
{
int index = (int)((Game.getDistance(p.Position, Game.particles[closePointInds[i]].Position) * 100) / d);
float lap = 0;
if (index <= 100 && index >= 0)
{
lap = laplacianLookup[index];
}
else
{
lap = Poly6WeightKernel(p.Position, Game.particles[closePointInds[i]].Position);
}
f += viscosity * Game.particles[closePointInds[i]].Mass * ((Game.particles[closePointInds[i]].Velocity - p.Velocity) / Game.particles[closePointInds[i]].Density) * lap;
}
// Console.WriteLine("viscosity force: " + f);
if (p.verbose)
{
Console.WriteLine("Viscocity: " + f);
}
p.NetForce += f;
}
public void calcPresssureForce(Sphere p)
{
Vector3 f = new Vector3(0, 0, 0);
int[] closePointInds = Game.neighborsIndicesConcatenated(p.Position);
for (int i = 0; i < closePointInds.Length; i++)
{
float fScalar = -1.0f * Game.particles[closePointInds[i]].Mass * ((p.Pressure + Game.particles[closePointInds[i]].Pressure) / (2 * Game.particles[closePointInds[i]].Density));
f += fScalar * spikyPressureKernel(p.Position, Game.particles[closePointInds[i]].Position);
}
float withSelf = -1.0f * p.Mass * ((p.Pressure + p.Pressure) / (2 * p.Density));
f -= withSelf * spikyPressureKernel(p.Position, p.Position);
if (p.verbose)
{
Console.WriteLine("pressure: " + f + " -- " + p.Density);
}
if (f.Length > 80)
{
f.Normalize();
f *= 80;
}
p.NetForce += f;
}
public void calcColorGradient(Sphere p)
{
Vector3 n = new Vector3(0, 0, 0);
int[] closePointInds = Game.neighborsIndicesConcatenated(p.Position);
for (int i = 0; i < closePointInds.Length; i++)
{
n += ((Game.particles[closePointInds[i]].Mass / Game.particles[closePointInds[i]].Density)) * Poly6GradientKernel(p.Position, Game.particles[closePointInds[i]].Position);
}
if (n.Length > 0)
{
n.Normalize();
}
p.normal = n;
}
public void calcSurfaceTension(Sphere p)
{
if (p.normal.Length < gradientFieldThreshold)
{
return;
}
Vector3 f = new Vector3(0, 0, 0);
Vector3 cNormal = new Vector3(0, 0, 0);
Vector3 cCurvature = new Vector3(0, 0, 0);
float K = p.Density;
int[] closePointInds = Game.neighborsIndicesConcatenated(p.Position);
for (int i = 0; i < closePointInds.Length; i++)
{
Vector3 r = p.Position - Game.particles[closePointInds[i]].Position;
if (Game.getDistance(p.Position, Game.particles[closePointInds[i]].Position) > 0)
{
cNormal += Game.particles[closePointInds[i]].Mass * CohesionKernel(p.Position, Game.particles[closePointInds[i]].Position) * (r / r.Length);
cCurvature += p.normal - Game.particles[closePointInds[i]].normal;
K += Game.particles[closePointInds[i]].Density;
}
}
cNormal *= p.Mass * -sigma;
cCurvature *= p.Mass * -sigma;
if (K > 0.0001)
{
K = 2 * p0 / K;
}
else
{
K = 0;
}
f = K * (cNormal + cCurvature);
if (p.verbose)
{
Console.WriteLine("Surface: " + f);
}
p.NetForce += f;
}
/**
* The following functions are implementations of the langrangian fluid equations provided here:
* https://www.cs.ubc.ca/~rbridson/fluidsimulation/fluids_notes.pdf
*
* This source was linked by Amir on the game physics course page
**/
public void calcDensity(Sphere p)
{
float dense = 1f;
int[] closePointInds = Game.neighborsIndicesConcatenated(p.Position);
for (int i = 0; i < closePointInds.Length; i++)
{
int index = (int)((Game.getDistance(p.Position, Game.particles[closePointInds[i]].Position) * 100) / d);
float poly = 0;
if (false)
{
poly = poly6Lookup[index];
}
else
{
poly = Poly6WeightKernel(p.Position, Game.particles[closePointInds[i]].Position);
}
dense += Game.particles[closePointInds[i]].Mass * poly;
}
p.Density = dense;
}
