agentscript/models/SlimeMoldModel.js

AgentScript Model in Model/View architecture

// Benny's tutorial:
// Welcome to the model editor! It is similar to the tutorial code blocks
// you saw before, but more flexible--everything can be customized here.
// I'll walk you through it in these comments.
//

//
// The first thing to notice is that there are two tabs up top:
// the model tab, and the view tab. The model tab is where you write
// code describing agent behavior, just like before.
//
// The view tab is totally new. That's where you customize the size of
// the world, and how agents and patches are drawn to the screen.
//

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

//
// The SlimeMoldModel below is based on the code we wrote in the tutorial,
// with two extra things added:
//
//  1) turtles now intentionally move toward patches with more pheromone
//  2) pheromone diffuses over time to neighboring patches
//

export default class SlimeMoldModel extends Model {
    wiggleAngle = 30 // This is an interesting variable to play with

    constructor(worldOptions = World.defaultOptions(20)) {
        super(worldOptions)
    }

    //
    // The setup function is like a "run once" block. It gets
    // executed only once, to setup the model.
    //

    setup() {
        // This line should look familiar. One important difference:
        // in the editor, you say "this.turtles" instead of "model.turtles"
        this.turtles.create(100)

        // The next line is what gives all patches a property called
        // "pheromone", equal to 0. We were doing this behind the scenes before.
        this.patches.setDefault('pheromone', 0)

        // Give each turtle a random starting position
        this.turtles.ask(turtle => {
            // Say something about the world here, and how you can mess
            // with it in the view tab
            let [x, y] = this.world.randomPoint()
            turtle.setxy(x, y)
        })
    }

    //
    // The step function is like a "run forever" block. It gets
    // executed over and over again.
    //

    step() {
        this.turtles.ask(turtle => {
            // let wiggleAngle = 30 // This is an interesting variable to play with

            // We look at three patches: directly ahead, ahead and to the right,
            // and ahead and to the left of the turtle
            let patchAhead = turtle.patchAhead(1)
            let patchRight = turtle.patchRightAndAhead(this.wiggleAngle, 1)
            let patchLeft = turtle.patchLeftAndAhead(this.wiggleAngle, 1)

            if (patchAhead && patchLeft && patchRight) {
                // If the patch to the right has the most pheromone, we turn right
                if (
                    patchRight.pheromone > patchLeft.pheromone &&
                    patchRight.pheromone > patchAhead.pheromone
                ) {
                    turtle.right(this.wiggleAngle)
                }

                // If the patch to the left has the most pheromone, we turn left
                if (
                    patchLeft.pheromone > patchRight.pheromone &&
                    patchLeft.pheromone > patchAhead.pheromone
                ) {
                    turtle.left(this.wiggleAngle)
                }

                // If the patch ahead has the most pheromone, we don't rotate at all
            }

            // If there's no patch to our right or left (because we're at the edge
            // of the world) we turn around.
            if (!patchRight) turtle.left(90)
            if (!patchLeft) turtle.right(90)

            // This last bit should look familiar. Move forward,
            // and add some pheromone to the turtle's patch
            turtle.forward(0.3)
            turtle.patch.pheromone += 10
        })

        // This part is new. patches.diffuse() causes each patch to give
        // some of its pheromone to its neighbors. Try changing the
        // diffusion amount and see what happens.
        this.patches.diffuse('pheromone', 0.5)

        // Evaporate the pheromone over time
        this.patches.ask(patch => {
            patch.pheromone *= 0.99
        })
    }
}

//
// You reached the end! Don't forget to check out the view tab if you
// haven't already. Have fun modeling!
//