Ray-Tracing/Canvas Test.html at master · Antonc3/Ray-Tracing · GitHub

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<body>
</body>
<style>
  canvas{
    background: white;
    margin: 10px;
  }
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script>
  class Canvas {
    constructor(w, h) {
      [this.w, this.h] = [w, h];
      this.canvas = document.createElement("canvas");
      this.canvas.width = this.w;
      this.canvas.height = this.h;

      document.querySelector('body').append(this.canvas);
      this.ctx = this.canvas.getContext('2d');
      this.imageData = this.ctx.getImageData(0, 0, this.w, this.h);
      this.data = this.imageData.data;
    }
    setPixel(x, y, r, g, b, a) {
      let index = 4 * (y * this.w + x);
      [this.data[index], this.data[index + 1], this.data[index + 2], this.data[index + 3]] = [r, g, b, a];
    }
    setPixels() {
      this.ctx.putImageData(this.imageData, 0, 0);
    }
  }

  let canvas = new Canvas(300, 300);

  function pixel(i, j) {
    if (i + j & 1) return [127, 127, 127];
    return [255, 255, 255];
  }

  for (let i = 0; i < canvas.h; i++) {
    for (let j = 0; j < canvas.w; j++) {
      let [r, g, b] = pixel(i, j);
      canvas.setPixel(j, i, r, g, b, 255);
    }
  }

  canvas.setPixels();
  //50% 127,127,127
  //25% 64,64,64
  //75% 192,192,192
  let d = document.createElement("div");
  d.style.background = "rgb(192,192,192)";
  d.style.width = 100;
  d.style.height = 100;
  document.querySelector('body').append(d);

</script>