alt Hacker NewsThe thing the author is trying to solve for here is reducing the amount of CPU used on the client when it rolls back the simulation and re-simulates to keep server authority.
He does this by only rolling back and re-simulating only a subset of the world, greatly reducing the amount of CPU required. It's cool that he's approaching this from the point of view of adding support for it in the physics engine itself, vs. making it something that the game has to do themselves.
Delta compression is an unrelated technique which reduce the amount of bandwidth sent from server to client, by sending only the differences between the snapshot at baseline frame n and the current snapshot frame m on the server.
Just want to clear this up for anybody trying to follow along. Bringing in delta compression is an unrelated thing (but somewhat similar conceptually). It might confuse people to talk about these things at the same time, if they're really just trying to understand what the author is doing in the article.
cheers
- Glenn
Replies
Yes thank you, you understand perfectly and thank you for explaining. Also, I LOVE your series of blog posts, thank you for making them!
Just to add to the general discussion for everyone following along - rollback netcode only sends inputs around, not state, so it doesn't really have much to send. I think I'm doing about 1.5 KB per second. When you point your mouse it sends that data in 10 bytes. There's not a lot to delta compress.
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No, in this context I meant delta-compression in the case of local roll-back.
The entire gamestate has to be rolled back when using this style of netcode, regardless of bandwidth, reducing the size of snapshots in memory can also reduce make it faster to rebuild.