agentscript/models/AntsModel.js

AgentScript Model in Model/View architecture

import World from 'https://code.agentscript.org/src/World.js'
import Model from 'https://code.agentscript.org/src/Model.js'
import * as util from 'https://code.agentscript.org/src/utils.js'

export default class AntsModel extends Model {
    population = 200
    speed = 1.0
    maxPheromone = 35
    diffusionRate = 0.3
    evaporationRate = 0.01
    wiggleAngle = 30 // degrees
    foodX = world => world.minX + 6
    foodY = () => 0
    nestX = world => world.maxX - 6
    nestY = () => 0
    foodSeekers = 0
    nestSeekers = 0

    // ======================

    constructor(worldOptions = World.defaultOptions(40)) {
        super(worldOptions)
    }

    setup() {
        this.turtles.setDefault('atEdge', 'bounce')
        this.setupPatches()
        this.setupTurtles()
    }
    setupPatches() {
        this.patches.ask(p => {
            p.isNest = p.isFood = false
            p.nestPheromone = p.foodPheromone = 0
        })
        this.patches
            .patchRectXY(this.nestX(this.world), this.nestY(this.world), 3, 3)
            .ask(p => {
                p.isNest = true
            })
        this.patches
            .patchRectXY(this.foodX(this.world), this.foodY(this.world), 3, 3)
            .ask(p => {
                p.isFood = true
            })
    }
    setupTurtles() {
        this.turtles.create(this.population, t => {
            t.setxy(this.nestX(this.world), this.nestY(this.world))
            this.resetTurtle(t, false) // sets t.pheromone to max
        })
    }
    resetTurtle(t, withFood) {
        t.carryingFood = withFood
        t.pheromone = this.maxPheromone
    }

    step() {
        this.updateTurtles()
        this.updatePatches()
    }
    updateTurtles() {
        this.foodSeekers = 0
        this.nestSeekers = 0
        this.turtles.ask(t => {
            if (t.id >= this.ticks) return // slowly release ants
            this.wiggleUphill(t)
            this.dropPheromone(t)
            if (t.carryingFood) {
                this.nestSeekers++
            } else {
                this.foodSeekers++
            }
        })
    }

    wiggleUphill(t) {
        const p = t.patch
        if (p.isOnEdge()) {
            // t.rotate(Math.PI)
            t.rotate(180)
        } else {
            // Note: neighbors is an AgentArray who's inCone uses radians.
            // const nAhead = p.neighbors.inCone(p, 2, Math.PI, t.theta)
            const nAhead = p.neighbors.inCone(p, 2, 180, t.heading)
            const pheromone = t.carryingFood ? 'nestPheromone' : 'foodPheromone'
            const [n, max] = nAhead.maxValOf(pheromone)
            if (max > 0.001 / this.maxPheromone) t.face(n)
        }
        t.rotate(util.randomCentered(this.wiggleAngle))
        t.forward(this.speed)
    }
    dropPheromone(t) {
        const p = t.patch
        if ((!t.carryingFood && p.isFood) || (t.carryingFood && p.isNest)) {
            this.resetTurtle(t, !t.carryingFood)
        }
        const pheromone = t.carryingFood ? 'foodPheromone' : 'nestPheromone'
        p[pheromone] += 0.1 * t.pheromone
        t.pheromone *= 0.9
    }

    updatePatches() {
        this.patches.diffuse('nestPheromone', this.diffusionRate)
        this.patches.diffuse('foodPheromone', this.diffusionRate)
        this.patches.ask(p => {
            p.foodPheromone *= 1 - this.evaporationRate
            p.nestPheromone *= 1 - this.evaporationRate
        })
    }
}