TheParallaxView app for iPhone and iPad

Only works on iPhones with TrueDepth camera

Illusion of depth by 3D head tracking using ARKit and TrueDepth camera. For best results, only one eye should be open (the app allows selecting which eye to track, or can try to select eye automatically)

By tracking the users head orientation and position, the eye position in 3D can be found. The app can then render a correct view on the display as seen from that position. For rendering this view an off-axis projection (non-symmetric camera frustum) is used. This gives the illusion that objects appear in front of and behind the screen.