// Daniel Shiffman

// http://natureofcode.com

​

// The "Vehicle" class

​

class Vehicle {

  constructor(x, y) {

    this.acceleration = createVector(0, 0);

    this.velocity = createVector(0, 0);

    this.position = createVector(x, y);

    this.r = 6;

    this.wandertheta = 0.0;

    this.maxspeed = 2;

    this.maxforce = 0.05;

  }

​

  run() {

    this.update();

    this.borders();

    this.display();

  }

  // 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);

  }

​

  wander() {

    let wanderR = 25;

    let wanderD = 80;

    let change = 0.3;

    this.wandertheta += random(-change,change);

​

    let circleloc = this.velocity.copy();

    circleloc.normalize();

    circleloc.mult(wanderD);

    circleloc.add(this.position);

    let h = this.velocity.heading();

    let circleOffSet = createVector(wanderR*cos(this.wandertheta+h),wanderR*sin(this.wandertheta+h));

    let target = p5.Vector.add(circleloc, circleOffSet);

    this.seek(target);

    //Render wandering circle, etc.

    if (debug) this.drawWanderStuff(this.position, circleloc, target, wanderR);

  }

  applyForce(force) {

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

    this.acceleration.add(force);

  }

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

  // STEER = DESIRED MINUS VELOCITY

  seek(target) {

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

    // Normalize desired and scale to maximum speed

    desired.normalize();

    desired.mult(this.maxspeed);

​

    // Steering = Desired minus Velocity

    var 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();

  }

  // Wraparound

  borders() {

    if (this.position.x < -this.r) this.position.x = width+this.r;

    if (this.position.y < -this.r) this.position.y = height+this.r;

    if (this.position.x > width+this.r) this.position.x = -this.r;

    if (this.position.y > height+this.r) this.position.y = -this.r;

  }

​

  // A method just to draw the circle associated with wandering

    drawWanderStuff(location, circle, target, rad) {

    stroke(0); 

    noFill();

    ellipseMode(CENTER);

    ellipse(circle.x,circle.y,rad*2,rad*2);

    ellipse(target.x,target.y,4,4);

    line(location.x,location.y,circle.x,circle.y);

    line(circle.x,circle.y,target.x,target.y);

    }

}