// Daniel Shiffman

// https://thecodingtrain.com/CodingChallenges/124-flocking-boids.html

// https://youtu.be/mhjuuHl6qHM

​

class Boid {

  constructor() {

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

    this.velocity = p5.Vector.random2D();

    this.velocity.setMag(random(2, 4));

    this.acceleration = createVector();

    this.maxForce = 0.2;

    this.maxSpeed = 5;

    this.r = 2;

  }

​

  edges() {

    if (this.position.x > width) {

      this.position.x = 0;

    } else if (this.position.x < 0) {

      this.position.x = width;

    }

    if (this.position.y > height) {

      this.position.y = 0;

    } else if (this.position.y < 0) {

      this.position.y = height;

    }

  }

​

  align(boids) {

    let perceptionRadius = 25;

    let steering = createVector();

    let total = 0;

    for (let other of boids) {

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

      if (other != this && d < perceptionRadius) {

        steering.add(other.velocity);

        total++;

      }

    }

    if (total > 0) {

      steering.div(total);

      steering.setMag(this.maxSpeed);

      steering.sub(this.velocity);

      steering.limit(this.maxForce);

    }

    return steering;

  }

​

  separation(boids) {

    let perceptionRadius = 24;

    let steering = createVector();

    let total = 0;

    for (let other of boids) {

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

      if (other != this && d < perceptionRadius) {

        let diff = p5.Vector.sub(this.position, other.position);

        diff.div(d * d);

        steering.add(diff);

        total++;

      }

    }

    if (total > 0) {

      steering.div(total);

      steering.setMag(this.maxSpeed);

      steering.sub(this.velocity);

      steering.limit(this.maxForce);

    }

    return steering;

  }

​

  cohesion(boids) {

    let perceptionRadius = 50;

    let steering = createVector();

    let total = 0;

    for (let other of boids) {

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

      if (other != this && d < perceptionRadius) {

        steering.add(other.position);

        total++;

      }

    }

    if (total > 0) {

      steering.div(total);

      steering.sub(this.position);

      steering.setMag(this.maxSpeed);

      steering.sub(this.velocity);

      steering.limit(this.maxForce);

    }

    return steering;

  }

​

  flock(boids) {

    let alignment = this.align(boids);

    let cohesion = this.cohesion(boids);

    let separation = this.separation(boids);

​

    alignment.mult(alignSlider.value());

    cohesion.mult(cohesionSlider.value());

    separation.mult(separationSlider.value());

​

    this.acceleration.add(alignment);

    this.acceleration.add(cohesion);

    this.acceleration.add(separation);

  }

​

  update() {

    this.position.add(this.velocity);

    this.velocity.add(this.acceleration);

    this.velocity.limit(this.maxSpeed);

    this.acceleration.mult(0);

  }

​

  render() {

    push();

    fill(127);

    stroke(200);

    let theta = this.velocity.heading() + radians(90);

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

    rotate(theta);

    beginShape();

    vertex(0, -this.r * 2);

    vertex(-this.r, this.r * 2);

    vertex(this.r, this.r * 2);

    endShape(CLOSE);

    pop();

  }

}