public FluidSimulationFrame(IntSize3 leveSetSizeStokesSize, int numParticles, IntSize3 navierStokesSize, float navierStokesCellSize)
{
LeveSetSizeStokesSize = leveSetSizeStokesSize;
Particles = new Vector3[numParticles];
Phi = new double[leveSetSizeStokesSize.Volume()];
ParticleMask = new bool[leveSetSizeStokesSize.Volume()];
NavierStokesGrid = new NavierStokesGrid(navierStokesSize, navierStokesCellSize);
}
public LevelSet(IntSize3 size, float cellSize, INavierStokesGrid grid)
{
Size = size;
CellSize = cellSize;
phi = new double[size.Volume()];
backPhi = new double[size.Volume()];
mass = new float[size.Volume()];
backMass = new float[size.Volume()];
states = new NavierStokesCellState[size.Volume()];
particleMass = new float[size.Volume()];
particleMask = new bool[size.Volume()];
for (int j = 0; j < Size.Height - 1; j++)
{
for (int i = 0; i < Size.Width - 1; i++)
{
var point = new Vector3(i, j, 0) * CellSize;
State(i, j) = grid.StateAtPoint(point);
}
}
}
public void TransferPhi(float deltaT, INavierStokesGrid grid)
{
/*
* Parallel.For(0, Size.Volume(), index =>
* {
* var j = index / Size.Width;
* var i = index - j * Size.Width;
*
* if (i < 1 || i >= Size.Width - 1 || j < 1 || j >= Size.Height - 1)
* return;
*
* var dpdx = (Phi(i + 1, j) - Phi(i - 1, j)) / (2 * CellSize);
* var dpdy = (Phi(i, j + 1) - Phi(i, j - 1)) / (2 * CellSize);
* var point = CellSize * (new Vector3(i, j, 0) + new Vector3(0.5f, 0.5f, 0.5f));
* var u = grid.GetVelocityAt(point) * deltaT;
* var deltaPhi = -u.X * dpdx - u.Y * dpdy;
* BackPhi(i, j) = Phi(i, j) + deltaPhi;
* });*/
/*
* for (int j = 1; j < Size.Height - 1; j++)
* for (int i = 1; i < Size.Width - 1; i++)
* {
* var dpdx = (Phi(i + 1, j) - Phi(i - 1, j)) / (2 * CellSize);
* var dpdy = (Phi(i, j + 1) - Phi(i, j - 1)) / (2 * CellSize);
* var point = CellSize * (new Vector3(i, j, 0) + new Vector3(0.5f, 0.5f, 0.5f));
* var u = grid.GetVelocityAt(point) * deltaT;
* var deltaPhi = -u.X * dpdx - u.Y * dpdy;
* BackPhi(i, j) = Phi(i, j) + deltaPhi;
* }*/
Array.Clear(backPhi, 0, backPhi.Length);
var halfVector = new Vector3(0.5f, 0.5f, 0.5f);
var cornerOffset = CellSize * halfVector;
Parallel.For(0, Size.Volume(), index =>
{
var j = index / Size.Width;
var i = index - j * Size.Width;
if (i < 1 || i >= Size.Width - 1 || j < 1 || j >= Size.Height - 1)
{
return;
}
var remainingDeltaT = deltaT;
var point = CellSize * (new Vector3(i, j, 0) + halfVector);
while (remainingDeltaT > 0)
{
var v = grid.GetVelocityAt(point);
var vlen = v.Length();
var localDeltaT = vlen * remainingDeltaT > CellSize ? CellSize / vlen : remainingDeltaT;
var potentialPoint = point + v * localDeltaT;
var potentialCorner = potentialPoint - cornerOffset;
var normPotentialCorner = potentialCorner / CellSize;
var npci = (int)normPotentialCorner.X;
var npcj = (int)normPotentialCorner.Y;
if (State(npci, npcj) == NavierStokesCellState.Object)
{
break;
}
point = potentialPoint;
remainingDeltaT -= localDeltaT;
}
var corner = point - cornerOffset;
//var centerPoint = new Vector3(Size.Width, Size.Height, 0) * CellSize / 2;
//while (grid.StateAtPoint(corner) == NavierStokesCellState.Object)
//{
// corner = Vector3.Lerp(corner, centerPoint, 0.05f);
//}
var ti = (int)(corner.X / CellSize);
var tj = (int)(corner.Y / CellSize);
var intCorner = new Vector3(ti, tj, 0) * CellSize;
var rightVolume = (corner.X - intCorner.X) / CellSize;
var upVolume = (corner.Y - intCorner.Y) / CellSize;
var leftVolume = 1 - rightVolume;
var downVolume = 1 - upVolume;
var originalMass = Phi(i, j);
var a00 = originalMass * leftVolume * downVolume;
var a01 = originalMass * leftVolume * upVolume;
var a10 = originalMass * rightVolume * downVolume;
var a11 = originalMass * rightVolume * upVolume;
lock (backWriteLock)
{
BackPhi(ti, tj) += a00;
BackPhi(ti + 1, tj) += a10;
BackPhi(ti, tj + 1) += a01;
BackPhi(ti + 1, tj + 1) += a11;
}
});
CodingHelper.Swap(ref phi, ref backPhi);
}
