void solveViscous()
{
float viscousStrength = fluidSystemDef.viscousStrength;
for (int i = 0; i < bodyContactBuffer.Count; i++)
{
FluidParticleBodyContact contact = bodyContactBuffer [i];
if ((contact.fp.flags & FluidParticleType.ViscousParticle) > 0)
{
// b2Vec2 v = b->GetLinearVelocityFromWorldPoint(p) -
// m_velocityBuffer.data[a];
Vector2 v = contact.body.velocity - contact.fp.velocity;
Vector2 f = viscousStrength * contact.mass * contact.weight * v;
contact.fp.velocity += getParticleInvMass() * f;
// b->ApplyLinearImpulse(-f, p, true);
}
}
for (int i = 0; i < contactBuffer.Count; i++)
{
FluidParticleContact contact = contactBuffer [i];
if ((contact.flags & FluidParticleType.ViscousParticle) > 0)
{
Vector2 v = contact.b.velocity - contact.a.velocity;
Vector2 f = viscousStrength * contact.weight * v;
contact.a.velocity += f;
contact.b.velocity -= f;
}
}
}
void solveDamping(float dt)
{
// reduces normal velocity of each contact
float linearDamping = fluidSystemDef.dampingStrength;
float quadraticDamping = 1 / getCriticalVelocity(dt);
for (int i = 0; i < bodyContactBuffer.Count; i++)
{
FluidParticleBodyContact contact = bodyContactBuffer [i];
FluidParticle a = contact.fp;
Vector2 p = a.position;
Vector2 v = contact.body.velocity - a.velocity;
float vn = Vector2.Dot(v, contact.normal);
if (vn < 0)
{
float damping = Mathf.Max(linearDamping * contact.weight, Mathf.Min(-quadraticDamping * vn, 0.5f));
Vector2 f = damping * contact.mass * vn * contact.normal;
a.velocity += getParticleInvMass() * f;
contact.body.AddForceAtPosition(-f / dt, p);
}
}
for (int i = 0; i < contactBuffer.Count; i++)
{
FluidParticleContact contact = contactBuffer [i];
Vector2 v = contact.b.velocity - contact.a.velocity;
float vn = Vector2.Dot(v, contact.normal);
if (vn < 0)
{
float damping = Mathf.Max(linearDamping * contact.weight, Mathf.Min(-quadraticDamping * vn, 0.5f));
Vector2 f = damping * vn * contact.normal;
contact.a.velocity += f;
contact.b.velocity -= f;
}
}
}
public override void reportFixtureAndParticle(FluidFixtureShape fixture, FluidParticle fp)
{
float d;
Vector2 n;
fixture.computeDistance(fp, out d, out n);
if ((d < fluidSystem.particleDiameter) &&
((fp.flags & FluidParticleType.WallParticle) == 0))
{
Rigidbody2D b = fixture.GetComponent <Rigidbody2D> ();
//Vector2 bp = b.transform.position;
float bm = b.mass;
// b2Vec2 bp = b->GetWorldCenter();
// float32 bI =
// b->GetInertia() - bm * b->GetLocalCenter().LengthSquared();
float invBm = bm > 0 ? 1 / bm : 0;
// float32 invBI = bI > 0 ? 1 / bI : 0;
float invAm = (fp.flags & FluidParticleType.WallParticle) > 0 ? 0 : fluidSystem.getParticleInvMass();
//Vector2 rp = fp.position - bp;
// float rpn = rp * n;
// float32 rpn = b2Cross(rp, n);
// float32 invM = invAm + invBm + invBI * rpn * rpn;
float invM = invAm + invBm;
FluidParticleBodyContact contact = new FluidParticleBodyContact
{
fp = fp,
body = b,
fixture = fixture,
weight = 1 - d * fluidSystem.inverseDiameter,
normal = -n,
mass = invM > 0 ? 1 / invM : 0
};
if (fixture.isTrigger())
{
fluidSystem.triggerContactBuffer.Add(contact);
fixture.notifyOnTrigger(contact);
}
else
{
fluidSystem.bodyContactBuffer.Add(contact);
}
// m_system->DetectStuckParticle(a);
}
}
public void notifyOnTrigger(FluidParticleBodyContact bodyContact)
{
foreach (GameObject receiver in listeners.ToArray())
{
MonoBehaviour[] components = receiver.GetComponents <MonoBehaviour> ();
foreach (MonoBehaviour component in components)
{
if (component is IFluidFixtureTriggerListener)
{
if (component.enabled)
{
IFluidFixtureTriggerListener l = component as IFluidFixtureTriggerListener;
l.fluidOnTrigger(bodyContact);
}
}
}
}
}
void computeWeight()
{
for (int i = 0; i < count; i++)
{
particleBuffer [i].weight = 0;
}
for (int i = 0; i < bodyContactBuffer.Count; i++)
{
FluidParticleBodyContact contact = bodyContactBuffer [i];
contact.fp.weight += contact.weight;
}
for (int i = 0; i < contactBuffer.Count; i++)
{
FluidParticleContact contact = contactBuffer [i];
contact.a.weight += contact.weight;
contact.b.weight += contact.weight;
}
}
void solvePressure(float dt)
{
// calculates pressure as a linear function of density
float criticalPressure = getCriticalPressure(dt);
float pressurePerWeight = fluidSystemDef.pressureStrength * criticalPressure;
float maxPressure = maxParticlePressure * criticalPressure;
for (int i = 0; i < count; i++)
{
FluidParticle fp = particleBuffer [i];
float h = pressurePerWeight * Mathf.Max(0f, fp.weight - minParticleWeight);
fp.accumulation = Mathf.Min(h, maxPressure);
}
// // ignores particles which have their own repulsive force
// if (m_allParticleFlags & k_noPressureFlags)
// {
// for (int32 i = 0; i < m_count; i++)
// {
// if (m_flagsBuffer.data[i] & k_noPressureFlags)
// {
// m_accumulationBuffer[i] = 0;
// }
// }
// }
// static pressure
if ((allParticleFlags & FluidParticleType.StaticPressureParticle) > 0)
{
for (int i = 0; i < count; i++)
{
FluidParticle fp = particleBuffer [i];
if ((fp.flags & FluidParticleType.StaticPressureParticle) > 0)
{
fp.accumulation += fp.staticPressure;
}
}
}
// applies pressure between each particles in contact
float velocityPerPressure = dt / (fluidSystemDef.density * particleDiameter);
for (int i = 0; i < bodyContactBuffer.Count; i++)
{
FluidParticleBodyContact contact = bodyContactBuffer [i];
FluidParticle a = contact.fp;
Rigidbody2D b = contact.body;
Vector2 p = a.position;
float h = a.accumulation + pressurePerWeight * contact.weight;
Vector2 f = velocityPerPressure * contact.weight * contact.mass * h * contact.normal;
a.velocity -= getParticleInvMass() * f;
b.AddForceAtPosition(f / dt, p);
}
float strength = fluidSystemDef.temperaturMixingStrength;
for (int i = 0; i < contactBuffer.Count; i++)
{
FluidParticleContact contact = contactBuffer [i];
FluidParticle a = contact.a;
FluidParticle b = contact.b;
float h = a.accumulation + b.accumulation;
Vector2 f = velocityPerPressure * contact.weight * h * contact.normal;
a.velocity -= f;
b.velocity += f;
float t = (b.temperature - a.temperature) * strength;
a.temperature += t;
b.temperature -= t;
if (Mathf.Abs(a.mass - b.mass) >= 0.01f)
{
if (b.mass < a.mass)
{
a = contact.b;
b = contact.a;
}
a.velocity.y += fluidSystemDef.densityStrength;
b.velocity.y -= fluidSystemDef.densityStrength;
}
else if (Mathf.Abs(a.temperature - b.temperature) >= 0.1f)
{
if (b.temperature > a.temperature)
{
a = contact.b;
b = contact.a;
}
a.velocity.y += fluidSystemDef.temperatureStrength;
b.velocity.y -= fluidSystemDef.temperatureStrength;
}
}
}
