// Seeking "vehicle" follows the mouse position
// Originally implemented by Daniel Shiffman which
// implements Craig Reynold's autonomous steering behaviors
// One vehicle "seeks"
// See: http://www.red3d.com/cwr/

let v;

function setup() {
  createCanvas(640, 360);
  v = new Vehicle(width / 2, height / 2);
}

function draw() {
  background(51);

  let mouse = createVector(mouseX, mouseY);

  // Draw an ellipse at the mouse position
  fill(33,150,34);
  stroke(200);
  strokeWeight(2);
  ellipse(mouse.x, mouse.y, 48, 48);

  // Call the appropriate steering behaviors for our agents
  v.arrive(mouse);
  v.update();
  v.display();

}
class Vehicle {
  constructor(x, y) {
    this.acceleration = createVector(0, 0);
    this.velocity = createVector(0, -3);
    this.position = createVector(x, y);
    this.r = 6;
    this.maxspeed = 4; // how fast it can go
    this.maxforce = 0.1; // set the ability to steer
  }

  // 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
  arrive(target) {

    var desired = p5.Vector.sub(target, this.position); // A vector pointing from the location to the target
		var distance = desired.mag();
		var boundaryRadius = 100;
		
		if(distance < boundaryRadius){
			var magnitude = (distance, 0, boundaryRadius, 0, this.maxspeed);
			desired.setMag(this.magnitude);
		}else{
			desired.setMag(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(160, 32, 240);
    stroke(200);
    strokeWeight(1);
    push();
    translate(this.position.x, this.position.y);
    rotate(theta);
    beginShape();
		// creates the triangle
    vertex(0, -this.r * 2);
    vertex(-this.r, this.r * 2);
    vertex(this.r, this.r * 2);
    endShape(CLOSE);
    pop();
  }
}