Ray.js

class Ray
{
  constructor(pos, angle)
  {
    this.pos = pos;
    this.dir = p5.Vector.fromAngle(angle);
  }

  show()
  {
    stroke(255);
    push();
    translate(this.pos.x, this.pos.y);
    line(0,0, this.dir.x*10, this.dir.y *10);
    pop();
  }

  setAngle(angle)
  {
    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();
  }

  cast(wall)
  {
    const x1 = wall.a.x;
    const y1 = wall.a.y;
    const x2 = wall.b.x;
    const y2 = wall.b.y;

    //two points of the intersect line
    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;

    //calculate denominator
    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;

    //check for value of t and u for line intersection
    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;
    }
  }
}