sensor.js

class Sensor {
  constructor(car) {
    this.car = car;
    this.rayCount = 7;
    this.rayLength = [120, 130, 150, 160, 150, 130, 120];
    this.raySpread = Math.PI / 2;
    this.rays = [];
    this.readings = [];
  }

  update(roadBorders, traffic) {
    this.#castRays();
    this.readings = [];
    for (let i = 0; i < this.rays.length; i++) {
      this.readings.push(this.#getReading(this.rays[i], roadBorders, traffic));
    }
  }

  #getReading(ray, roadBorders, traffic) {
    let touches = [];
    for (let i = 0; i < roadBorders.length; i++) {
      const touch = getIntersection(ray[0], ray[1], roadBorders[i][0], roadBorders[i][1]);
      if (touch) {
        touches.push(touch);
      }
    }

    for (let i = 0; i < traffic.length; i++) {
      const poly = traffic[i].polygon;
      for (let j = 0; j < poly.length; j++) {
        const value = getIntersection(ray[0], ray[1], poly[j], poly[(j + 1) % poly.length]);
        if (value) {
          touches.push(value);
        }
      }
    }

    if (touches.length === 0) {
      return null;
    } else {
      const carX = this.car.x;
      const isLeftLane = carX < roadBorders[0][0].x;

      const offsets = touches.map((e) => e.offset);
      const minOffset = Math.min(...offsets);
      const closestTouch = touches.find((e) => e.offset === minOffset);

      if (isLeftLane) {
        if (closestTouch.offset < 0) {
          return closestTouch;
        } else {
          return null;
        }
      } else {
        if (closestTouch.offset > 0) {
          return closestTouch;
        } else {
          return null;
        }
      }
    }
  }

  #castRays() {
    this.rays = [];
    for (let i = 0; i < this.rayCount; i++) {
      const rayAngle = lerp(this.raySpread / 2, -this.raySpread / 2, this.rayCount === 1 ? 0.5 : i / (this.rayCount - 1)) + this.car.angle;
      const start = { x: this.car.x, y: this.car.y };
      const rayLength = this.rayLength[i];
      const end = {
        x: this.car.x - Math.sin(rayAngle) * rayLength,
        y: this.car.y - Math.cos(rayAngle) * rayLength,
      };
      this.rays.push([start, end]);
    }
  }

  draw(ctx) {
    for (let i = 0; i < this.rayCount; i++) {
      let end = this.rays[i][1];
      if (this.readings[i]) {
        end = this.readings[i];
      }
      ctx.beginPath();
      ctx.lineWidth = 2;
      ctx.strokeStyle = "yellow";
      ctx.moveTo(this.rays[i][0].x, this.rays[i][0].y);
      ctx.lineTo(end.x, end.y);
      ctx.stroke();
      ctx.beginPath();
      ctx.lineWidth = 2;
      ctx.strokeStyle = "black";
      ctx.moveTo(this.rays[i][1].x, this.rays[i][1].y);
      ctx.lineTo(end.x, end.y);
      ctx.stroke();
    }
  }
}