private static string GetFluidResponseSource(
ICollisionSettings settings,
string roughSurfaceSource)
{
var src = "";
if (settings.RoughSurface)
{
src += roughSurfaceSource;
}
src += $@"
float projVelocity = dot(n, velocity);
float3 normalVelocity = projVelocity * n;
float3 tangentVelocity = velocity - normalVelocity;
float3 v = 0;
if (projVelocity < 0)
{{
v -= ((1 + Elasticity) * projVelocity) * n;
}}
v -= Friction * tangentVelocity;
// Repulsion force
{(settings.RepulsionForce ? "force += v * (1.0f / mass) * RepulsionForce * invDt;" : "")}
velocity += v;
oldPosition = position;
age += (LifetimeLoss * lifetime);";
return(src);
}
private static string GetFluidResponseSource(
ICollisionSettings settings,
string roughSurfaceSource)
{
var hasPreviousPosition = false;
var hasLifetime = false;
var block = settings as VFXBlock;
if (block != null)
{
hasPreviousPosition = block.GetData().IsCurrentAttributeWritten(FluvioFXAttribute.PreviousPosition);
hasLifetime = block.GetData().IsCurrentAttributeWritten(VFXAttribute.Alive);
}
var src = "";
if (settings.RoughSurface)
{
src += roughSurfaceSource;
}
src += $@"
float projVelocity = dot(n, velocity);
float3 normalVelocity = projVelocity * n;
float3 tangentVelocity = velocity - normalVelocity;
float3 v = 0;
if (projVelocity < 0)
{{
v -= ((1 + Bounce) * projVelocity) * n;
}}
v -= Friction * tangentVelocity;
// Repulsion force
{(settings.RepulsionForce ? "force += v * (1.0f / mass) * RepulsionForce * invDt;" : "")}
velocity += v;
{(hasPreviousPosition ? "previousPosition = position - v;" : "")}
age += (LifetimeLoss * lifetime);";
return(src);
}
public static IEnumerable <VFXPropertyWithValue> GetInputProperties(
ICollisionSettings collisionSettings,
IEnumerable <VFXPropertyWithValue> baseProperties)
{
var properties = baseProperties;
if (collisionSettings.BoundaryPressure)
{
properties = properties
.Concat(FluvioFXBlock.PropertiesFromType(typeof(BoundaryPressureProperties)));
}
if (collisionSettings.BoundaryViscosity)
{
properties = properties
.Concat(FluvioFXBlock.PropertiesFromType(typeof(BoundaryViscosityProperties)));
}
if (collisionSettings.RepulsionForce)
{
properties = properties
.Concat(FluvioFXBlock.PropertiesFromType(typeof(RepulsionForceProperties)));
}
return(properties);
}
public static string GetCollisionSource(
ICollisionSettings settings,
string baseSource,
string collisionResponseSource,
string roughSurfaceSource)
{
if (!settings.BoundaryPressure && !settings.BoundaryViscosity)
{
return(baseSource.Replace(collisionResponseSource, GetFluidResponseSource(settings, roughSurfaceSource)));
}
var proxyTestSource = baseSource
.Replace("float3 nextPos = position + velocity * deltaTime;", "")
.Replace("nextPos", "proxyPosition")
.Replace("position", "dummyPosition")
.Replace(collisionResponseSource, " collisionTest = true;");
var split = proxyTestSource.Split(new []
{
"\r\n",
"\r",
"\n"
}, StringSplitOptions.None);
proxyTestSource = string.Join("\n ", split);
var data = (settings as VFXBlock)?.GetData();
return($@"{FluvioFXBlock.CheckAlive(data)}
{{
float3 offset, proxyPosition, dummyPosition, dist;
float density = 0;
float pressure, lenSq, diffSq;
bool collisionTest = false;
float searchRadius = solverData_KernelSize.x;
float step = solverData_KernelSize.w;
float3 gridJitter = float3(FIXED_RAND3(0x5f7b48e2)) * step;
float x, y, z;
// Fluid density calculation
for(x = -searchRadius; x < searchRadius; x += step)
{{
for(y = -searchRadius; y < searchRadius; y += step)
{{
for(z = -searchRadius; z < searchRadius; z += step)
{{
// Get proxy particle position
offset = float3(x, y, z);
proxyPosition = position + offset;
// Snap to random grid, but keep the grid consistent per particle
proxyPosition = (round(proxyPosition / step) * step) + gridJitter;
collisionTest = false;
{proxyTestSource}
if (collisionTest)
{{
// Range check
// TODO: We can optimize this away since we know the precise step size
dist = position - proxyPosition;
lenSq = dot(dist, dist);
if (lenSq < solverData_KernelSize.y)
{{
// Sum density
diffSq = solverData_KernelSize.y - lenSq;
density += mass * Poly6Calculate(diffSq, solverData_KernelFactors.x);
}}
}}
}}
}}
}}
density = max(density, solverData_Fluid_MinimumDensity);
pressure = solverData_Fluid_GasConstant * (density - solverData_Fluid_Density);
float2 neighborDensityPressure = float2(
solverData_Fluid_Density,
{(settings.BoundaryPressure ? "GasConstant * solverData_Fluid_Density" : "0")});
float len, len3, diff, bodyRadiusSq, scalar;
float3 f, neighborVelocity, bodyDist;
for(x = -searchRadius; x < searchRadius; x += step)
{{
for(y = -searchRadius; y < searchRadius; y += step)
{{
for(z = -searchRadius; z < searchRadius; z += step)
{{
if (abs(x) < step && abs(y) < step && abs(z) < step)
{{
continue;
}}
// Get proxy particle position
offset = float3(x, y, z);
proxyPosition = position + offset;
// Snap to random grid, but keep the grid consistent per particle
proxyPosition = (round(proxyPosition / step) * step) + gridJitter;
collisionTest = false;
{proxyTestSource}
if (collisionTest)
{{
// Range check
// TODO: We can optimize this away since we know the precise step size
dist = position - proxyPosition;
lenSq = dot(dist, dist);
if (lenSq < solverData_KernelSize.y)
{{
// For kernels
lenSq = dot(dist, dist);
len = sqrt(lenSq);
len3 = len * len * len;
diffSq = solverData_KernelSize.y - lenSq;
diff = solverData_KernelSize.x - len;
{(settings.BoundaryPressure ? @"// Pressure term
scalar = mass
* (pressure + neighborDensityPressure.y) / (neighborDensityPressure.x * 2.0f);
f = SpikyCalculateGradient(dist, diff, len, solverData_KernelFactors.y);
f *= scalar;
force -= f;" : "")}
{(settings.BoundaryViscosity ? @"// Viscosity term
bodyDist = proxyPosition - CenterOfGravity;
bodyRadiusSq = sqrt(dot(bodyDist, bodyDist));
neighborVelocity = Velocity + (AngularVelocity / FLUVIO_TAU) * FLUVIO_TAU * bodyRadiusSq;
scalar = mass
* ViscosityCalculateLaplacian(
diff,
solverData_KernelSize.z,
solverData_KernelFactors.z)
* (1.0f / neighborDensityPressure.x);
f = neighborVelocity - velocity;
f *= scalar * Viscosity;
force += f;" : "")}
}}
}}
}}
}}
}}
// Write totals to density/pressure (zw)
density = max(densityPressure.z + density, solverData_Fluid_MinimumDensity);
pressure = solverData_Fluid_GasConstant * (density - solverData_Fluid_Density);
densityPressure.zw = float2(density, pressure);
}}
{baseSource.Replace(collisionResponseSource, GetFluidResponseSource(settings,roughSurfaceSource))}");
}