Multi User Support

[TheBricktop]

Hello,
im thinking about adding networking to openbrush, probably using mirror networking or something easier like osc for starters.
How one could tackle synchronizing the painting area? By recording brush moves and passing them as a series of vectors with params or as a obj string?

[mikeskydev]

Hi!
There's a small group of us that are also really interested in adding networking. There's a channel in our Discord where we've discussed and some investigation has been made, but no one's got particularly far https://discord.gg/xNFSVUdP42

Multibrush of course has the multiplayer capability, but is unfortunately closed source and using a closed source networking library.

Library choice is one of the main things to figure out. Personally, I'd like something that can be self hosted and run easily by anyone, to preserve this functionality as much as possible. It should support online matchmaking and rooms for general use, but also configurable to target a server on the local network for setups such as schools and museums, where internet access may not be as simple as a home user.

Some packages also have open source client libraries but closed source servers, which I feel is not the correct path either.

Members of the Tilt Brush team have spoken about unreleased multiplayer prototypes, and how they went about implementing the sync:

The code for the multiplayer prototype was fairly simple: serialize Command and squirt it across the network to a relay that bounced them reliably to all other people who joined the channel. Do a continual distributed leader election to decide a leader. On join, ask for the undo history and the leader sends it to you

https://discord.com/channels/783806589991780412/803681768049737799/803760281066930256

Command is referencing this class https://github.com/icosa-gallery/open-brush/blob/main/Assets/Scripts/Commands/BaseCommand.cs

[andybak]

There's a useful discussion starting here: https://discord.com/channels/783806589991780412/804251629993197618/859193005286359080

I copied parts of it into the developer notes which lots of other useful pointers in it: https://docs.google.com/document/d/1BLKHNDjp-hZ8Ju03PhdU1crLOxURB14BtId8YKCp3tk/edit

@Daniel-Fan has also done some work on recording and replaying the avatar head and hands that might feed into this: https://github.com/Daniel-Fan/open-brush/tree/add-strokeIndicator

[billyquith]

Need to move to Unity 2020: #135

[gabrieldevsouza]

Is this still in progress?

[mikeskydev]

Absolutely 😀

[mikeskydev]

The baseline pass of the multiplayer stack has been implemented, so I'm going to close this in favor of mini issues for the remaining tasks!