Boids

Simulate classic boid flocking behavior on a list of transforms.

This action combines three steering rules:

• Separation keeps boids from crowding together.
• Alignment steers boids to match nearby movement.
• Cohesion pulls boids toward the local group.

You can also add obstacle avoidance, keep boids inside soft bounds, and constrain movement to planes like XY for 2D or XZ for 3D.

Parameters

Parameter	Description
Boids	The list of transforms to simulate.
Axis	Which axes movement uses, such as XY, XZ, or XYZ.
Neighbor Radius	How far a boid looks for neighbors for alignment and cohesion.
Separation Radius	How close boids can get before they push away from each other.
Separation Weight	Strength of the separation steering force.
Alignment Weight	Strength of the alignment steering force.
Cohesion Weight	Strength of the cohesion steering force.
Avoidance Weight	Strength of obstacle avoidance steering.
Max Force	Maximum steering acceleration.
Initial Speed	Starting speed for newly initialized boids. Use 0 to start at max speed.
Max Speed	Maximum movement speed.
Min Speed Fraction	Minimum speed as a fraction of max speed.
Randomize Start	Randomize initial movement direction for each boid.
Align To Velocity	Rotate each boid to face its current velocity.
Angular Speed	Maximum turn speed when aligning to velocity.
Local Forward Axis	Which local axis should face the travel direction.
Use Obstacles	Enable obstacle avoidance settings.
Obstacles	Optional list of obstacle transforms to avoid.
Obstacle Avoid Radius	Distance where boids start steering away from obstacles.
Obstacle Radius	Fallback obstacle size when colliders are not used.
Use Bounds	Enable soft world-space bounds steering.
Bounds Min	Minimum corner of the allowed area.
Bounds Max	Maximum corner of the allowed area.
Bounds Margin	Distance from the bounds where inward steering begins.
Bounds Weight	Strength of the bounds steering force.
Lock Unused Axes To Zero	Keeps unused axes pinned to zero, which is useful for 2D-style setups.

Example

1. Add your agents to a Transform List.
2. Set Axis to XY for a 2D flock or XZ for ground-based 3D movement.
3. Start with a larger Neighbor Radius than Separation Radius.
4. Tune the three weights until the flock spreads, regroups, and turns the way you want.
5. Enable Use Bounds if you want the flock to stay inside an area without hard clamping.

Notes

• This action moves the listed transforms directly every frame.
• Inactive GameObjects in the boid list are ignored.
• If Align To Velocity is enabled, rotation updates are based on the current movement direction.
• Soft bounds steer boids back inward near the edges instead of snapping them.