drawGrid missing in startAnimationLoop

[rjpgt]

First of all, thank you for this tutorial.

This is not important. But since you had talked about an updated version of drawGrid I was wondering why a call to it is missing in the init function and in startAnimationLoop. I think it looks good to have the grid drawn for now.

  startAnimationLoop(function (deltaTime) {
    clearCanvas(ctx, scene.camera);
    drawGrid(ctx, scene.camera);
    scene.update(deltaTime);
    drawScene(ctx, scene);
  });
}