let ray;

let particle; 

​

function setup() {

  createCanvas(400, 400);

  for (let i = 0; i < 5; i++) {

    let x1 = random(width);

    let x2 = random(width);

    let y1 = random(height);

    let y2 = random(height);

    walls[i] = new Boundary(x1, y1, x2, y2);

  }

  wall = new Boundary(300, 100, 100, 300);

  ray = new Ray (100, 200);

  particle = new Particle();

}

​

function draw() {

  background(0);

  for (let wall of walls) {

    wall.show();

  }

  particle.update(mouseX, mouseY);

  particle.show();

  particle.look(walls);

  // ray.show();

  // ray.lookAt(mouseX, mouseY)

  // let pt = ray.cast(wall); 

  // if (pt) {

  //   fill(255); 

  //   ellipse(pt.x, pt.y, 8, 8);

  // }

}

​

​

class Particle {

  constructor() {

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

    this.rays = [];

    for (let a = 0; a < 360; a += 5) {

      this.rays.push(new Ray(this.pos, radians(a)));

    }

  }

  update(x, y) {

    this.pos.set(x, y);

  }

  look(walls) {

    for (let ray of this.rays) {

      let closest = null;

      let record = Infinity;

      for (let wall of walls) {

        const pt = ray.cast(wall);

        if (pt) {

          const d = p5.Vector.dist(this.pos, pt);

          if (d < record) {

            record = d;

            closest = pt;

          }

        }

        if (closest) {

          line(this.pos.x, this.pos.y, closest.x, closest.y);

        }

      }

    }

  }

  show() {

    fill(255);

    ellipse(this.pos.x, this.pos.y, 4);

    for (let ray of this.rays) {

      ray.show();

    }

  }

}

​

​

class Ray {

  constructor(pos, angle) {

    this.pos = pos;

    this.dir = p5.Vector.fromAngle(angle);

  }

  lookAt(x, y) {

    this.dir.x = x - this.pos.x;

    this.dir.y = y - this.pos.y;

    this.dir.normalize();

  }

  show() {

    stroke(255);

    push()

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

    line(0, 0, this.dir.x * 10, this.dir.y * 10);

    pop();

  }

  cast(wall) {

    const x1 = wall.a.x;

    const y1 = wall.a.y;

    const x2 = wall.b.x;

    const y2 = wall.b.y;

    const x3 = this.pos.x;

    const y3 = this.pos.y;

    const x4 = this.pos.x + this.dir.x;

    const y4 = this.pos.y + this.dir.y;

    const den = (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4); 

    if (den == 0) {

      return;

    }

    const t =  ((x1 - x3) * (y3 - y4) - (y1 - y3) * (x3 - x4)) / den;

    const u = -((x1 - x2) * (y1 - y3) - (y1 - y2) * (x1 - x3)) / den;

    if (t > 0 && t < 1 && u > 0) {

      const pt = createVector();

      pt.x = x1 + t * (x2 - x1);

      pt.y = y1 + t * (y2 - y1);

      return pt;

    } else {

      return;

    }

  }

}

​

​

class Boundary {

  constructor(x1, y1, x2, y2) {

    this.a = createVector(x1, y1);

    this.b = createVector(x2, y2);

  }

  show() {

    stroke(255);

    line(this.a.x, this.a.y, this.b.x, this.b.y);    

  }

}