/// <summary>
/// Run simulation
/// </summary>
public IEnumerator CalculateVelocities()
{
int simulationStep = 0;
for (int currentIndex = 0; currentIndex < boids.Count; currentIndex++)
{
// Optimization trick: in each frame we simulate only small percent of all boids
simulationStep++;
if (simulationStep > maxSimulationSteps)
{
simulationStep = 0;
yield return(null);
}
var boid = boids[currentIndex];
// Search for nearest neighbours
neighbours.Clear();
for (int i = 0; i < boids.Count; i++)
{
Boid neighbour = boids[i];
Vector3 toNeighbour = neighbour.position - boid.position;
if (toNeighbour.sqrMagnitude < interactionRadius)
{
neighbours.Add(neighbour);
if (neighbours.Count == maxBoids)
{
break;
}
}
}
if (neighbours.Count < 2)
{
continue;
}
boid.velocity = Vector3.zero;
boid.cohesion = Vector3.zero;
boid.separation = Vector3.zero;
boid.alignment = Vector3.zero;
// Calculate boid parameters
int separationCount = 0;
for (int i = 0; i < neighbours.Count && i < maxBoids; i++)
{
Boid neighbour = neighbours[i];
boid.cohesion += neighbour.position;
boid.alignment += neighbour.velocity;
Vector3 toNeighbour = neighbour.position - boid.position;
if (toNeighbour.sqrMagnitude > 0 &&
toNeighbour.sqrMagnitude < separationDistance * separationDistance)
{
boid.separation += toNeighbour / toNeighbour.sqrMagnitude;
separationCount++;
}
}
// Clamp all parameters to safe values
boid.cohesion /= Mathf.Min(neighbours.Count, maxBoids);
boid.cohesion = Vector3.ClampMagnitude(boid.cohesion - boid.position, maxSpeed);
boid.cohesion *= cohesionCoefficient;
if (separationCount > 0)
{
boid.separation /= separationCount;
boid.separation = Vector3.ClampMagnitude(boid.separation, maxSpeed);
boid.separation *= separationCoefficient;
}
boid.alignment /= Mathf.Min(neighbours.Count, maxBoids);
boid.alignment = Vector3.ClampMagnitude(boid.alignment, maxSpeed);
boid.alignment *= alignmentCoefficient;
// Calculate resulting velocity
Vector3 velocity = boid.cohesion + boid.separation + boid.alignment;
boid.velocity = Vector3.ClampMagnitude(velocity, maxSpeed);
if (boid.velocity == Vector3.zero)
{
// Prevent boids from stopping
boid.velocity = Random.onUnitSphere * maxSpeed;
}
}
}