Dictionary <int, ParticleAggregate> PartitionParticles(PhysicalParticle[] particles, Vector3 cell_size)
{
Dictionary <int, ParticleAggregate> spatial_hash = new Dictionary <int, ParticleAggregate>();
for (int i = 0; i < particles.Length; i++)
{
PhysicalParticle p = particles[i];
int x_ind = Mathf.FloorToInt(p.position.x / cell_size.x);
int y_ind = Mathf.FloorToInt(p.position.y / cell_size.y);
int z_ind = Mathf.FloorToInt(p.position.z / cell_size.z);
int hash = x_ind * 113 + y_ind * 12769 + z_ind * 1442897;
ParticleAggregate bucket;
if (!spatial_hash.TryGetValue(hash, out bucket))
{
bucket = new ParticleAggregate();
spatial_hash[hash] = bucket;
}
bucket.particles.Add(p);
bucket.center_of_mass += p.position * p.mass;
bucket.total_mass += p.mass;
}
foreach (KeyValuePair <int, ParticleAggregate> pair in spatial_hash)
{
pair.Value.center_of_mass /= pair.Value.total_mass;
}
return(spatial_hash);
}
Vector3 HashingForce(Dictionary <int, ParticleAggregate> spatial_hash, ParticleAggregate curr_bucket, PhysicalParticle particle, float deltaT)
{
ParticleAggregate other_bucket;
Vector3 total_force = Vector3.zero;
foreach (KeyValuePair <int, ParticleAggregate> other_cell in spatial_hash)
{
other_bucket = other_cell.Value;
if (curr_bucket == other_bucket)
{
continue;
}
Vector3 position_difference = other_bucket.center_of_mass - particle.position;
float distance = position_difference.magnitude;
if (distance < MIN_DISTANCE)
{
continue;
}
float pd_cubed = distance * distance * distance;
total_force += other_bucket.total_mass * particle.mass / pd_cubed * position_difference;
}
foreach (PhysicalParticle other_particle in curr_bucket.particles)
{
if (other_particle == particle)
{
continue;
}
Vector3 position_difference = other_particle.position - particle.position;
float distance = position_difference.magnitude;
if (distance < MIN_DISTANCE)
{
continue;
}
float pd_cubed = distance * distance * distance;
total_force += other_particle.mass * particle.mass / pd_cubed * position_difference;
}
total_force *= GRAVITATIONAL_CONSTANT;
//Debug.Log(total_force);
return(total_force);
}
void hash_gravity_worker_func()
{
KeyValuePair <int, ParticleAggregate> curr_item;
while (!should_stop)
{
if (!need_updating || (curr_spatial_hash == null && next_spatial_hash == null))
{
continue;
}
lock (hash_lock)
{
if (curr_spatial_hash == null)
{
curr_spatial_hash = next_spatial_hash;
iter = curr_spatial_hash.GetEnumerator();
}
curr_item = iter.Current;
if (!iter.MoveNext())
{
need_updating = false;
if (next_spatial_hash != null)
{
curr_spatial_hash = next_spatial_hash;
}
iter = curr_spatial_hash.GetEnumerator();
}
}
ParticleAggregate curr_bucket = curr_item.Value;
if (curr_bucket == null)
{
continue;
}
foreach (PhysicalParticle particle in curr_bucket.particles)
{
particle.totalForce = HashingForce(curr_spatial_hash, curr_bucket, particle, this.deltaT);
//Debug.Log("Force: " + total_force + "\t Velocity: " + particle.velocity + "\t dt: " + this.deltaT);
}
}
}
