We've been hard at work on our rhythm game projects, and we've managed to create a feature we've never thought we could do with Blueprints only, coupled with our current experience. But alas, it has happened.
We've created a beatmap editor inside Unreal 4 using only Blueprints and Rama's Victory Blueprint plugin (it's a godsend, check it out if you're using UE4!).
For the editor, we used osu!'s editor as a reference, and for now it can only create and edit Taiko type beatmaps. We plan to overhaul it almost completely for our own game, but first we had to try if it was even possible to create.
The editor uses .ogg files as music, and creates a text file with a matching name for each new .ogg file. The file contains BPM and title information, as well as all the beat objects or notes in the song - similar to how osu!'s .osz files work. We dubbed ours as .beatmap files though.
Once the file is created, the user can enter a BPM calibrator that lets them tap a button in time with the music. The editor then calculates based on those clicks the BPM of the song, or alternatively, the BPM can be input manually.
After this is done, the actual editor lets users put notes down on each beat of the song, change their colors around and then save the beatmap. The beatmap can then be played in play mode.
The whole thing is very raw right now, because we haven't had as much time to work on it as we wanted to, but it's getting there. This tool will be very useful for developing our rhythm games, and we plan to include it in the game too, so users can create custom content with songs they like.
At this point we're starting to feel like anything is possible in Blueprints with the right nodes and tools. Of course knowing C++ would help greatly, so we're going to get on that, too, but there's no rush.