Method propagate

src/main/java/trace/simulation/Boids.kt:50–85

    var W = 1.0

    private fun propagate(a: Boid, all: MutableList<Boid>, speed: Double): Boid {

        val all2 = mutableListOf<Boid>()
        all2.addAll(all)

        all2.sortBy { it.at.distanceSquared(a.at) }
        all.sortBy { it.at.distanceSquared(a.at) }

        all2.addAll(0, important)
        val n = Math.min(7 + important.size, all2.size - 1)

        val center = Vec2(a.at)
        val heading = Vec2(a.heading) * W // LPF

        for (x in 1 until n) {
            center %= center + all2[x].at
            heading %= heading + all2[x].heading
        }

        center %= center * (1.0 / (1.0 + n))
        heading %= heading * (1.0 / (W + n))

        if (heading.length() == 0.0) heading %= Vec2(0.0, 0.0).noise(1.0F).safeNormalize()
        else heading.normalize()

        // other behaviors

        if (all.size > 1) {
            tweakHeading(heading, a, all[1], center, tooFar)
            for(i in important.size-1 downTo 0)
            {
                tweakHeading(heading, a, all2[i], all2[i].at, tooFar*5)
            }
        }
        return Boid(a.at + heading * a.speed * speed, heading, a.speed, a.misc)
    }

    private fun tweakHeading(heading: Vec2, a: Boid, all: Boid, center : Vec2, tooFar : Double) {
        val Z = all.at.distance(a.at)