Responding to head look

Let's make the text move with our head, so it doesn't appear to be stuck to your face! As you look left or right, we'll move the text in the opposite direction, so it appears to be stationary in space.

To do this, we'll start in MainActivity. In the onNewFrame method, we'll determine the horizontal head rotation angle and pass that to the overlayView object.

In MainActivity, define onNewFrame:

    public void onNewFrame(HeadTransform headTransform) {
        final float[] angles = new float[3];
        headTransform.getEulerAngles(angles, 0);
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                overlayView.setHeadYaw(angles[1]);
            }
        });
    }

The onNewFrame method receives the current HeadTransform instance as an argument, which is an object that provides the current head pose.

There are various ways to mathematically represent the head pose, such as a forward XYZ direction vector, or a combination...