GridPathModel.js

import AgentArray from 'https://agentscript.org/src/AgentArray.js'
import Model from 'https://agentscript.org/src/Model.js'

// prettier-ignore
const WorldOptions = {
 minX: 0, maxX: 9,
 minY: 0, maxY: 9,
 minZ: 0, maxZ: 2,
}

export default class GridPathModel extends Model {
 constructor(worldOptions = WorldOptions) {
 super(worldOptions) // default world options if "undefined"
 }

 setup() {
 this.patches.ask(p => (p.occupied = false))
 this.walker = this.turtles.createOne()
 this.walker.moveTo(this.patches.first())
 this.walker.patch.occupied = true
 }

 step() {
 if (this.done) return

 this.floodFill()

 const ok = this.okNeighbors(this.walker.patch)
 this.walker.choices = ok.length // used by view

 let turtle = this.walker.hatch()[0]
 ;[this.walker, turtle] = [turtle, this.walker] // swap walker & turtle

 this.walker.moveTo(ok.oneOf())
 this.walker.patch.occupied = true

 this.links.createOne(this.walker, turtle)

 this.done = this.patches.last().occupied

 if (this.done) {
 this.walker.choices = this.okNeighbors(this.walker.patch).length
 console.log(`Model done at tick: ${this.ticks}`)
 }
 }

 okNeighbors(p) {
 return p.neighbors4.filter(p => p.ok)
 }

 floodFill() {
 this.patches.ask(p => (p.ok = false))
 let pset = new AgentArray(this.patches.last())
 let step = 0
 while (pset.length > 0) {
 pset.ask(p => (p.ok = true))
 pset.ask(p => (p.step = step))
 let pnext = pset
 .map(p => p.neighbors4)
 .flat()
 .uniq()
 pset = pnext.filter(n => !n.ok && !n.occupied)
 step++
 }
 }
}