Google released augmented reality doodling app Just a Line back in March. The neat (if frivolous) app lets you draw shapes in the air that realistically float in place as you move around them, looking through your phone's display. Now, two users are able to share one doodling space across separate devices — even if one is an Android phone and the other is an iPhone.
The update was teased at Google I/O this year and made possible on Android by ARCore v1.2, along with what Google calls Cloud Anchors. The drawings from both devices are continuously synced to and accessed from a shared Firebase Realtime Database, allowing the same interactive image to be viewed across screens.
Apparently, this makes Just a Line the world's first cross-platform collaborative augmented reality app — which, considering what a nascent and specific niche that is, is certainly believable. Sharing AR experiences, especially more complex ones, seems like it could be a lot of fun. You can snag the newest version of Just a Line from APK Mirror; it'll work on any ARCore-enabled device.