void SimulateStep()
{
FluidMath.VelStep(N, M, u, v, uS, vS, viscosity, 1.0f);
FluidMath.DensStep(N, M, d, dS, u, v, diffusion, 1.0f);
// Clear source arrays.
for (int i = 0; i < size; i++)
{
dS[i] = 0; uS[i] = 0; vS[i] = 0;
}
}
void AddCenteredRect(float coverage, float densityFull)
{
int xH = GetXH(coverage);
int yH = GetYH(coverage);
int offsetX = GetOffsetX(xH);
int offsetY = GetOffsetY(yH);
float fill = ((N * M) / (xH * yH)) * densityFull;
for (int i = offsetX; i <= offsetX + xH - 1; i++)
{
for (int j = offsetY; j <= offsetY + yH - 1; j++)
{
dS[FluidMath.IX(N, i, j)] = fill;
}
}
}
void Draw(SKSurface surface, int width, int height)
{
Stopwatch sw = new Stopwatch();
if (canRender)
{
var canvas = surface.Canvas;
canvas.Clear(SKColors.White);
sw.Restart();
using (var paint = new SKPaint())
{
paint.Style = SKPaintStyle.Fill;
SKRect rect = new SKRect();
Color densityColor;
float xCord = 0;
float yCord = 0;
float xInc, yInc;
float colorScale = 1.0f;
float density;
xInc = width / (float)N;
yInc = height / (float)M;
// Loop through, match simulation format of first cell (0,0) at bottom left.
for (int i = 1; i <= N; i++)
{
yCord = height;
for (int j = 1; j <= M; j++)
{
// Set bounds of rectangle.
rect.Left = xCord;
rect.Top = yCord - yInc;
rect.Right = xCord + xInc;
rect.Bottom = yCord;
// Read from corresponding cell to set color based on density. Note bottom left in simulation is index 1,1.
density = d[FluidMath.IX(N, i, j)];
colorScale = colorScaleFactor * Math.Max(1.0f, Math.Min(1.0f, (1 / density)));
if (density > 0.05)
{
densityColor = new Color(baseColor.R * colorScale, baseColor.G * colorScale, baseColor.B * colorScale, baseColor.A * Math.Pow(density, 1 - Math.Min(1.0, density)));
paint.Color = densityColor.ToSKColor();
canvas.DrawRect(rect, paint);
}
// Decrement y for next rectangle.
yCord -= yInc;
}
// Increment x for next rectangle.
xCord += xInc;
}
canvas.Flush();
}
var drawTime = sw.ElapsedMilliseconds;
if (drawTime > 10)
{
#if DEBUG
Debug.WriteLine("Slow render time: {0} milliseconds.", drawTime);
#endif
}
}
}
void Spin()
{
float cellVelocity = 0, addU = 0, addV = 0;
int xH = GetXH(SPIN_FORCE_COVERAGE); int yH = GetYH(SPIN_FORCE_COVERAGE);
int average = (xH + yH) / 2;
xH = average; yH = average;
int offsetX = GetOffsetX(xH);
int offsetY = GetOffsetY(yH);
float gravity = this.gravity * 1.2f; // Extra force for spin.
// Normalize and reverse X & Y direction.
MotionVector normalizedMotion = new MotionVector();
normalizedMotion.X = (double)N / (N + M) * (N + M / 30); normalizedMotion.Y = (double)M / (N + M) * (N + M / 30);
switch (spin)
{
case 0:
normalizedMotion.X *= 1; normalizedMotion.Y *= 1;
break;
case 1:
normalizedMotion.X *= 1; normalizedMotion.Y *= -1;
break;
case 2:
normalizedMotion.X *= -1; normalizedMotion.Y *= -1;
break;
case 3:
normalizedMotion.X *= -1; normalizedMotion.Y *= 1;
break;
}
if (lastSpin.ElapsedMilliseconds >= 120 || !lastSpin.IsRunning)
{
lastSpin.Restart();
spin += 1;
if (spin > 3)
{
spin = 0;
}
}
if (lastSpinMove.ElapsedMilliseconds >= 1920 || !lastSpinMove.IsRunning)
{
lastSpinMove.Restart();
// Find random spot where there is some fluid (>10% density).
do
{
spinOffsetAddX = spinRandom.Next(-(N - xH - 2) / 2, (N - xH - 2) / 2);
spinOffsetAddY = spinRandom.Next(-(M - yH - 2) / 2, (M - yH - 2) / 2);
} while (d[FluidMath.IX(N, offsetX + spinOffsetAddX, offsetY + spinOffsetAddY)] < 0.10f);
}
offsetX += spinOffsetAddX;
offsetY += spinOffsetAddY;
for (int i = offsetX; i <= offsetX + xH - 1; i++)
{
for (int j = offsetY; j <= offsetY + yH - 1; j++)
{
if (d[FluidMath.IX(N, i, j)] > 0)
{
addU = gravity * (float)normalizedMotion.X * d[FluidMath.IX(N, i, j)];
addV = gravity * (float)normalizedMotion.Y * d[FluidMath.IX(N, i, j)];
}
else
{
addU = gravity * (float)normalizedMotion.X;
addV = gravity * (float)normalizedMotion.Y;
}
uS[FluidMath.IX(N, i, j)] = addU;
vS[FluidMath.IX(N, i, j)] = addV;
// Set u.
cellVelocity = u[FluidMath.IX(N, i, j)] + addU;
if (cellVelocity < -terminalVelocity)
{
uS[FluidMath.IX(N, i, j)] = addU - (cellVelocity - -terminalVelocity);
}
else if (cellVelocity > terminalVelocity)
{
uS[FluidMath.IX(N, i, j)] = addU - (cellVelocity - terminalVelocity);
}
else
{
uS[FluidMath.IX(N, i, j)] = addU;
}
// Set v.
cellVelocity = v[FluidMath.IX(N, i, j)] + addV;
if (cellVelocity < -terminalVelocity)
{
vS[FluidMath.IX(N, i, j)] = addV - (cellVelocity - -terminalVelocity);;
}
else if (cellVelocity > terminalVelocity)
{
vS[FluidMath.IX(N, i, j)] = addV - (cellVelocity - terminalVelocity);
}
else
{
vS[FluidMath.IX(N, i, j)] = addV;
}
}
}
}
void AddForces()
{
float cellVelocity = 0, addU = 0, addV = 0;
int xH = GetXH(FORCE_COVERAGE); int yH = GetYH(FORCE_COVERAGE);
int average = (xH + yH) / 2;
xH = average; yH = average;
int offsetX = GetOffsetX(xH);
int offsetY = GetOffsetY(yH);
// Normalize and reverse X & Y direction.
MotionVector normalizedMotion = new MotionVector();
double normal = 1.0d; //; Math.Sqrt(Math.Pow(deviceMotion.X, 2) + Math.Pow(deviceMotion.Y, 2) + Math.Pow(deviceMotion.Z, 2));
normalizedMotion.X = deviceMotion.X / -normal; normalizedMotion.Y = deviceMotion.Y / -normal;
for (int i = offsetX; i <= offsetX + xH - 1; i++)
{
for (int j = offsetY; j <= offsetY + yH - 1; j++)
{
if (d[FluidMath.IX(N, i, j)] > 0)
{
addU = gravity * (float)normalizedMotion.X * d[FluidMath.IX(N, i, j)];
addV = gravity * (float)normalizedMotion.Y * d[FluidMath.IX(N, i, j)];
}
else
{
addU = gravity * (float)normalizedMotion.X;
addV = gravity * (float)normalizedMotion.Y;
}
uS[FluidMath.IX(N, i, j)] = addU;
vS[FluidMath.IX(N, i, j)] = addV;
// Set u.
cellVelocity = u[FluidMath.IX(N, i, j)] + addU;
if (cellVelocity < -terminalVelocity)
{
uS[FluidMath.IX(N, i, j)] = addU - (cellVelocity - -terminalVelocity);
}
else if (cellVelocity > terminalVelocity)
{
uS[FluidMath.IX(N, i, j)] = addU - (cellVelocity - terminalVelocity);
}
else
{
uS[FluidMath.IX(N, i, j)] = addU;
}
// Set v.
cellVelocity = v[FluidMath.IX(N, i, j)] + addV;
if (cellVelocity < -terminalVelocity)
{
vS[FluidMath.IX(N, i, j)] = addV - (cellVelocity - -terminalVelocity);;
}
else if (cellVelocity > terminalVelocity)
{
vS[FluidMath.IX(N, i, j)] = addV - (cellVelocity - terminalVelocity);
}
else
{
vS[FluidMath.IX(N, i, j)] = addV;
}
}
}
}
