// Daniel Shiffman

// http://natureofcode.com

​

// The "Vehicle" class

​

class Vehicle {

  constructor(x, y) {

    this.acceleration = createVector(0, 0);

    this.velocity = createVector(0, -2);

    this.position = createVector(x, y);

    this.r = 6;

    this.maxspeed = 8;

    this.maxforce = 0.2;

  }

​

  // Method to update location

  update() {

    // Update velocity

    this.velocity.add(this.acceleration);

    // Limit speed

    this.velocity.limit(this.maxspeed);

    this.position.add(this.velocity);

    // Reset accelerationelertion to 0 each cycle

    this.acceleration.mult(0);

  }

​

  applyForce(force) {

    // We could add mass here if we want A = F / M

    this.acceleration.add(force);

  }

​

  // A method that calculates a steering force towards a target

  // STEER = DESIRED MINUS VELOCITY

  seek(target) {

​

    let desired = p5.Vector.sub(target, this.position); // A vector pointing from the location to the target

​

    // Scale to maximum speed

    desired.setMag(this.maxspeed);

​

    // Steering = Desired minus velocity

    let steer = p5.Vector.sub(desired, this.velocity);

    steer.limit(this.maxforce); // Limit to maximum steering force

​

    this.applyForce(steer);

  }

​

  display() {

    // Draw a triangle rotated in the direction of velocity

    var theta = this.velocity.heading() + PI / 2;

    fill(127);

    stroke(200);

    strokeWeight(1);

    push();

    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();

  }

}