Flocking systems are really common in VFX, and much easier than you might think. It’s not unusual to use them to create birds flying through the background of a shot to add a little bit of life to it if it feels like it needs it. It’s great for fish too - the process is identical - but it’s rare to see them flying, and rare to film underwater.

Meet the Boid

At its heart, each bird or fish in a flocking system is a particle with an animation attached to it. We call that “boid”, pronounced like a New Yorker saying “bird”.

Three Behaviours

You then set behaviours to determine how the boids behave -

Separation is how close the boids will tolerate being to their neighbours.

Alignment is how closely a boid matches its heading to the average heading of its neighbours.

Cohesion is the unity of the whole group. Higher cohesion pulls the boids in towards the middle (a high separation will have them still keeping their distance even as they crowd towards that middle).

Direct Your Own Flock

With that, you can create and direct completely different flocks and shoals, even exporting the results to Blender/Unreal/wherever if you want - so don’t delay, start frantically flocking right flocking now!

What's Inside

• Separation, alignment, and cohesion, the three rules behind any flock
• The boid's eye view: perception radius and field of view
• Directing the flock: goals, fear, and obstacles
• Complexity from simplicity: banking, variation, and the small details that sell it