#ifihadglass I would write an app it to train me in various flavors of billiards game. In billiards it is crucial to decide how you position your cue where exactly to hit on the cue ball, and at what speed to hit. The app will draw guide-lines on the camera view to guide the player, perhaps also zoom in the cue-ball to show where exactly the player needs to hit. You may need to apply a spin, find the sweet spot, and also want to make a slipping analysis; the app will also assist in those advanced scenarios. In some pool games there are pockets, so the tool will also capture the location of pockets as well as balls, and draw guidelines around them.