// Daniel Shiffman

// http://natureofcode.com

​

class Particle {

  constructor(brain) {

    // All of our physics stuff

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

    this.acceleration = createVector();

    this.velocity = createVector();

    // Fitness and DNA

    this.fitness = 0;

    // Particle can be created with an existing neural network

    if (brain) {

      this.brain = brain;

    } else {

      // Create a new neural network

      const options = {

        inputs: 2,

        outputs: 2,

        task: 'regression',

        noTraining: true

      }

      this.brain = ml5.neuralNetwork(options);

      this.brain.mutate(1);

    }

  }

​

  // fitness = one divided by distance squared

  calcFitness() {

    const d = p5.Vector.dist(this.position, target);

    this.fitness = pow(1 / d, 2);

    return this.fitness;

  }

​

  applyForce(force) {

    this.acceleration.add(force);

  }

​

  // Input to neural network: x,y position

  // Output from neural network: direction and magnitude for velocity

  // Exercise prompt: what it output was a steering force!

  think() {

    const inputs = [];

    inputs[0] = this.position.x / width;

    inputs[1] = this.position.y / height;

    const outputs = this.brain.predictSync(inputs);

    this.velocity = p5.Vector.fromAngle(outputs[0].value * TWO_PI);

    this.velocity.setMag(outputs[1].value * 5);

  }

​

​

  update() {

    this.velocity.add(this.acceleration);

    this.position.add(this.velocity);

    this.acceleration.mult(0);

  }

​

  show() {

    stroke(255);

    fill(255, 150);

    ellipse(this.position.x, this.position.y, 8);

  }

}