class Rocket {

  constructor(dna) {

    this.position = createVector(width / 2, height);

    this.velocity = createVector();

    this.acceleration = createVector();

    this.completed = false;

    this.crashed = false;

    this.fitness = 0;

​

    if (dna) {

      this.dna = dna;

    } else {

      this.dna = new DNA();

    }

  }

​

  applyForce(force) {

    this.acceleration.add(force);

  }

​

  update() {

    let d = dist(this.position.x, this.position.y, target.x, target.y);

    if (d < 10) {

      this.completed = true;

      this.position = target.copy();

    }

​

    if (

      this.position.x > obstacle.x &&

      this.position.x < obstacle.x + obstacle.w &&

      this.position.y > obstacle.y &&

      this.position.y < obstacle.y + obstacle.h

    ) {

      this.crashed = true;

    }

​

    if (

      this.position.x > width ||

      this.position.x < 0 ||

      this.position.y > height ||

      this.position.y < 0

    ) {

      this.crashed = true;

    }

​

    this.applyForce(this.dna.genes[count]);

    if (!this.completed && !this.crashed) {

      this.velocity.add(this.acceleration);

      this.position.add(this.velocity);

      this.acceleration.mult(0);

      this.velocity.limit(4);

    }

  }

​

  show() {

    push();

    noStroke();

    fill(255, 150);

    translate(this.position.x, this.position.y);

    rotate(this.velocity.heading());

    rectMode(CENTER);

    rect(0, 0, 25, 5);

    pop();

  }

​

  calcFitness() {

    let d = dist(this.position.x, this.position.y, target.x, target.y);

    this.fitness = map(d, 0, width, width, 0);

    if (this.completed) {

      this.fitness *= 10;

    }

    if (this.crashed) {

      this.fitness /= 10;

    }

  }

}

​

// DNA class

class DNA {

  constructor(genes) {

    if (genes) {

      this.genes = genes;

    } else {

      this.genes = [];

      for (let i = 0; i < lifespan; i++) {

        this.genes[i] = p5.Vector.random2D();

        this.genes[i].setMag(maxForce);

      }

    }

  }

​

  crossover(partner) {

    let newGenes = [];

    let mid = floor(random(this.genes.length));

    for (let i = 0; i < this.genes.length; i++) {

      if (i > mid) {

        newGenes[i] = this.genes[i];

      } else {

        newGenes[i] = partner.genes[i];

      }

    }

    return new DNA(newGenes);

  }

​

  mutate() {

    for (let i = 0; i < this.genes.length; i++) {

      if (random(1) < mutationRate) {

        this.genes[i] = p5.Vector.random2D();

        this.genes[i].setMag(maxForce);

      }

    }

  }

}

​

// GA variables

let population;

let lifespan = 400;

let count = 0;

let target;

let maxForce = 0.2;

let mutationRate = 0.01;

let obstacle;

​

function setup() {

  createCanvas(400, 300);

  population = new Population();

  target = createVector(width / 2, 50);

  obstacle = {

    x: width / 2 - 50,

    y: height / 2 - 25,

    w: 100,

    h: 50

  };

}

​

function draw() {

  background(0);

​

  population.run();

​

  count++;

  if (count === lifespan) {

    population.evaluate();

    population.selection();

    count = 0;

  }

​

  fill(255);

  ellipse(target.x, target.y, 16, 16);

​

  fill(175);

  rect(obstacle.x, obstacle.y, obstacle.w, obstacle.h);

}

​

// Population class

class Population {

  constructor() {

    this.rockets = [];

    this.popsize = 100;

    this.matingPool = [];

​

    for (let i = 0; i < this.popsize; i++) {

      this.rockets[i] = new Rocket();

    }

  }

​

  evaluate() {

    let maxFitness = 0;

    for (let i = 0; i < this.popsize; i++) {

      this.rockets[i].calcFitness();

      if (this.rockets[i].fitness > maxFitness) {

        maxFitness = this.rockets[i].fitness;

      }

    }

​

    for (let i = 0; i < this.popsize; i++) {

      this.rockets[i].fitness /= maxFitness;

    }

​

    this.matingPool = [];

    for (let i = 0; i < this.popsize; i++) {

      let n = this.rockets[i].fitness * 100;

      for (let j = 0; j < n; j++) {

        this.matingPool.push(this.rockets[i]);

      }

    }

  }

​

  selection() {

    let newRockets = [];

    for (let i = 0; i < this.rockets.length; i++) {

      let parentA = random(this.matingPool).dna;

      let parentB = random(this.matingPool).dna;

      let child = parentA.crossover(parentB);

      child.mutate();

      newRockets[i] = new Rocket(child);

    }

    this.rockets = newRockets;

  }

​

  run() {

    for (let i = 0; i < this.popsize; i++) {

      this.rockets[i].update();

      this.rockets[i].show();

    }

  }

}

​

​