void ApplyPreconditioner(Array2Df x, Array2Df y, Array2Df m)
{
//Maybe Incomplete Cholesky??
int i, j;
float d;
m.Reset();
// solve L*m=x
for (j = 1; j < x.ny - 1; ++j)
{
for (i = 1; i < x.nx - 1; ++i)
{
if (marker[i, j] == FLUID)
{
d = x[i, j] - poisson[i - 1, j, 1] * preconditioner[i - 1, j] * m[i - 1, j]
- poisson[i, j - 1, 2] * preconditioner[i, j - 1] * m[i, j - 1];
m[i, j] = preconditioner[i, j] * d;
}
}
}
// solve L'*y=m
y.Reset();
for (j = x.ny - 2; j > 0; --j)
{
for (i = x.nx - 2; i > 0; --i)
{
if (marker[i, j] == FLUID)
{
d = m[i, j] - poisson[i, j, 1] * preconditioner[i, j] * y[i + 1, j]
- poisson[i, j, 2] * preconditioner[i, j] * y[i, j + 1];
y[i, j] = preconditioner[i, j] * d;
}
}
}
}
public PICParticles(PICGrid grid, PICMain.SimType type)
{
this.grid = grid;
this.type = type;
np = 0;
sum = new Array2Df(grid.pressure.nx + 1, grid.pressure.ny + 1);
}
public PICGrid(float gravity, int nx, int ny, float domainSize)
{
this.gravity = gravity;
domainx = domainSize;
domainy = ny * domainx / nx;
h = domainx / nx;
invH = 1 / h;
u = new Array2Df(nx + 1, ny);
v = new Array2Df(nx, ny + 1);
pressure = new Array2Df(nx, ny);
marker = new Array2Di(nx, ny);
phi = new Array2Df(nx, ny);
du = new Array2Df(nx, ny);
dv = new Array2Df(nx, ny);
poisson = new Array2Dx3f(nx, ny);
preconditioner = new Array2Df(nx, ny);
m = new Array2Df(nx, ny);
r = new Array2Df(nx, ny);
z = new Array2Df(nx, ny);
s = new Array2Df(nx, ny);
rhsB = new Array2Df(nx, ny);
}
public void SolveDistance(float p, float q, ref float r)
{
float d = Mathf.Min(p, q) + 1;
if (d > Mathf.Max(p, q))
{
d = (p + q + Mathf.Sqrt(2 - sqr(p - q))) / 2;
}
if (d < r)
{
r = d;
}
}
float GetPressureCoeff(Array2Df press, Array2Di marker, int u, int v)
{
u = Mathf.Max(0, u);
v = Mathf.Max(0, v);
u = Mathf.Min(this.pressure.nx - 1, u);
v = Mathf.Min(this.pressure.ny - 1, v);
if (marker[u, v] == SOLID)
{
return(1);
}
else
{
return(0);
}
}
float GetNeighborPressureCoeff(Array2Df press, Array2Di marker, int u, int v)
{
u = Mathf.Max(0, u);
v = Mathf.Max(0, v);
u = Mathf.Min(this.pressure.nx - 1, u);
v = Mathf.Min(this.pressure.ny - 1, v);
if (marker[u, v] == FLUID)
{
return(-press[u, v]);
}
else
{
return(0);
}
}
public void ApplyPoisson(Array2Df x, Array2Df y)
{
y.Reset();
for (int j = 1; j < poisson.ny - 1; ++j)
{
for (int i = 1; i < poisson.nx - 1; ++i)
{
if (marker[i, j] == FLUID)
{
y[i, j] = poisson[i, j, 0] * x[i, j]
+ poisson[i - 1, j, 1] * x[i - 1, j]
+ poisson[i, j, 1] * x[i + 1, j]
+ poisson[i, j - 1, 2] * x[i, j - 1]
+ poisson[i, j, 2] * x[i, j + 1];
}
}
}
}
void accumulate(Array2Df accum, float q, int i, int j, float fx, float fy)
{
float weight;
weight = (1 - fx) * (1 - fy);
accum[i, j] += weight * q;
sum[i, j] += weight;
weight = fx * (1 - fy);
accum[i + 1, j] += weight * q;
sum[i + 1, j] += weight;
weight = (1 - fx) * fy;
accum[i, j + 1] += weight * q;
sum[i, j + 1] += weight;
weight = fx * fy;
accum[i + 1, j + 1] += weight * q;
sum[i + 1, j + 1] += weight;
}
/* call this function to incorporate c[] when transfering particles to grid */
/* This function should take the c_pa^n values from c, and update them, with proper weighting, */
/* into the correct grid velocity values in accum */
void affineFix(Array2Df accum, Vector2 c, int i, int j, float fx, float fy)
{
var w00 = (1 - fx) * (1 - fy);
var w10 = fx * (1 - fy);
var w01 = (1 - fx) * fy;
var w11 = fx * fy;
var d00 = new Vector2(-fx, -fy);
var d10 = new Vector2(1 - fx, -fy);
var d01 = new Vector2(-fx, 1 - fy);
var d11 = new Vector2(1 - fx, 1 - fy);
accum[i, j] += Vector2.Dot(c, d00) * w00;
accum[i + 1, j] += Vector2.Dot(c, d10) * w10;
accum[i, j + 1] += Vector2.Dot(c, d01) * w01;
accum[i + 1, j + 1] += Vector2.Dot(c, d11) * w11;
}
/* this function computes c from the gradient of w and the velocity field from the grid. */
Vector2 computeC(Array2Df ufield, int i, int j, float fx, float fy)
{
var f00 = ufield[i, j];
var f10 = ufield[i + 1, j];
var f01 = ufield[i, j + 1];
var f11 = ufield[i + 1, j + 1];
var w00 = new Vector2((1 - fx), (1 - fy));
var w10 = new Vector2(fx, (1 - fy));
var w01 = new Vector2((1 - fx), fy);
var w11 = new Vector2(fx, fy);
var gw00 = new Vector2(-(1 - fy), -(1 - fx));
var gw10 = new Vector2(1 - fy, -fx);
var gw01 = new Vector2(-fy, 1 - fx);
var gw11 = new Vector2(fy, fx);
return(gw00 * f00 + gw10 * f10 +
gw01 * f01 + gw11 * f11);
}
