Separation

The final basic motivator is separation, i.e. avoiding each other, for fear of bumping into each other.

With the experience gained by the other two motivators we will start by creating a separation function.

begin separation(boid, flock)

end

We would like to know each heading that would bring us towards a flock member, and then avoid these headings. For the first part we can determine a list of headings first. We do have to make sure that we do not determine the heading with ourselfs.

headings = []
for b in flock begin
    if b <> boid then begin
        h = arctangent(b.y - boid.y, b.x - boid.x)
        headings.push(h)
    end
end

With all these headings we would like to go the opposite way. One way of doing that is to calculate the average heading, and add a heading of \(\pi\).

heading
for h in headings begin
    heading += h
end
heading/headings.size + PI

Experimentation

What other ways can you think of to avoid your flock mates?