If you are using any Custom ROM in OnePlus 2, you will face a problem in Camera App. No Doubt CM 13 by Grarak is awesome but only the disappointing Snap Camera App make me to not use it as a daily driver. You will face the same issue in Exodus ROM, Resurrection Remix, and all other custom ROMs as well but not in Hydrogen OS as it is a Stock OS of the Chinese version of OnePlus 2.

Official OnePlus Camera App for CM/AOSP ROM [Ported from OOS 3.0] : http://www.droidphoria.com/2016/04/OOS-3.0-Camera-App-for-Custom-ROM-OnePlus-2.html

How to Install Oxygen OS 3.0 Camera App in any Custom ROM based on CM / AOSP :

Tutorial is here : http://www.droidphoria.com/2016/04/OOS-3.0-Camera-App-for-Custom-ROM-OnePlus-2.html