const maxSpeed = 3;

const maxForce = 0.1;

let roads = [];let vehicles = [];

​

​

function setup() {

  createCanvas(400, 400);

  road = new Road(createVector(100,200),createVector(300,200))

  append(roads,road);

  vehicle = new Vehicle(road);

  append(vehicles,vehicle)

}

​

function draw() {

  background(220);

  for(let road of roads){

    road.render(); 

  }

  for(let vehicle of vehicles){

    vehicle.update();

    vehicle.render(); 

  }

}

​

class Vehicle{

  constructor(road){

    road.addVehicle(this);

    this.road = road;

    this.pos = road.start.copy();

    this.pos.y += 100;

    this.maxSpeed = maxSpeed;

    this.maxForce = maxForce;

    this.vel = createVector();

  }

  update(){

    let target = this.road.getNextPoint(this.pos);

    let desired = p5.Vector.sub(target, this.pos);

    desired.setMag(this.maxSpeed);

    let steering = p5.Vector.sub(desired,this.vel);

    steering.limit(this.maxForce);

    this.vel.add(steering);

    this.pos.add(this.vel);

  }

  render(){

    stroke(0,0,0);

    fill(255,0,0);

    circle(this.pos.x,this.pos.y,size)

  }

}

class Road{

  constructor(startPos,endPos){

    this.start = startPos;

    this.end = endPos;

    this.population = [];

  }

  addVehicle(vehical){

    append(this.population,vehical)

  }

  render(){

    stroke(0,0,0);

    line(this.start.x,this.start.y,this.end.x,this.end.y)

  }

  getNextPoint(currentPos){

    let roadVector = p5.Vector.sub(this.end,this.start);

    let toCurrent = p5.Vector.sub(currentPos,this.start);

    let projectedLength = toCurrent.dot(roadVector);

    projectedLength = constrain(projectedLength,0,1);

    return p5.Vector.add(this.start,roadVector.mult(projectedLength))

  }

}