SymmetryScript.Boids.lua

Settings = {space = "pointer"}

Parameters = {
    copies = {label = "Number of copies", type="int", min=1, max=24, default=8},
    separationForce = {label = "Separation Amount", type="float", min=0, max=10, default = 1.5},
    alignmentForce = {label = "Alignment Amount", type="float", min=0, max=10, default = 5.0},
    --cohesionForce = {label = "Cohesion Amount", type="float", min=0, max=10, default = 1.0},
    originForce = {label = "Pointer Attraction", type="float", min=0, max=10, default = 5.0},
}

cohesionForce = 1.0 -- We need more room for parameters!

symmetryHueShift = require "symmetryHueShift"

local Boid = {}
Boid.__index = Boid

function Boid.new(position, velocity)
    local self = setmetatable({}, Boid)
    self.position = position
    self.velocity = velocity
    self.orientation = Rotation:LookRotation(self.velocity, Vector3.up)
    return self
end

function Boid:update(dt, boids)

    local sep, align, coh = self:calculateForces(boids)

    -- Calculate a force vector pointing towards the origin
    local attractionToOrigin = Vector3.zero - self.position
    attractionToOrigin = attractionToOrigin.normalized

    self.velocity = self.velocity + (sep * separationForce)
    self.velocity = self.velocity + (align * alignmentForce)
    self.velocity = self.velocity + (coh * cohesionForce)

    -- Apply the attraction to origin force
    self.velocity = self.velocity + (attractionToOrigin * originForce)

    self.velocity = self.velocity:ClampMagnitude(5)
    self.position = self.position + (self.velocity * dt)
    self.orientation = Rotation:LookRotation(self.velocity, Vector3.up)
end

function Boid:calculateForces(boids)
    local separation = Vector3.zero
    local alignment = Vector3.zero
    local cohesion = Vector3.zero
    local count = 0

    for _, other in ipairs(boids) do
        if other ~= self then
            local direction = self.position - other.position
            local distanceSquared = direction.sqrMagnitude
            if distanceSquared < 25 and distanceSquared > 0 then
                separation = separation + (direction / distanceSquared)
                alignment = alignment + other.velocity
                cohesion = cohesion + other.position
                count = count + 1
            end
        end
    end

    if count > 0 then
        separation = separation / count
        alignment = (alignment / count).normalized
        cohesion = ((cohesion / count) - self.position).normalized
    end

    return separation, alignment, cohesion
end

local boids = {}

function Start()
    initialHsv = Brush.colorHsv
end

function randomFloat(x)
    -- Returns a random float in the range [-x, x]
    return -x + (2 * x) * Random.value
end

function Main()
    if Brush.triggerPressedThisFrame then
        -- Initialize boids with random positions and velocities
        boids = {}
        for i = 1, copies do
            local position = Random.insideUnitSphere * 0.25
            local velocity = Random.insideUnitSphere * 0.1
            boids[i] = Boid.new(position, velocity)
        end
        symmetryHueShift.generate(copies, initialHsv)
    end
    return updateBoids(0.01)
end

function updateBoids(dt)
    pointers = Path:New()
    for _, boid in ipairs(boids) do
        boid:update(dt, boids)
        pointers:Insert(Transform:New(boid.position, boid.orientation))
    end
    return pointers
end