initCanvas() {
    if (typeof document !== 'undefined') {
      const canvas = document.createElement('canvas');
      // Default width and height, to fix webgl issue in safari
      canvas.width = 2;
      canvas.height = 2;
      return canvas;
    } else if (typeof OffscreenCanvas !== 'undefined') {
      return new OffscreenCanvas(0, 0);
    }
  }
The thread dimensions, x, y and z
@type {Array|null}