DOTS NetCode: MMO locations, portals, items

My game's world is presented as a set of locations, connected via portals in a random way. The world may get pretty large and players don't need all the locations loaded at once, as well as all the items or characters on these locations.

What's the best approach to spawn/despawn locations and their contents? My solution can figure out how far the location is from the player via custom collections, filled upon the portals connections. But the built-in distance checking won't work since it's grid-based.

How do I present these locations? They are static pieces of the environment, but they may contain pickable items and movable characters. Ghosts? Or should I use some RPC-based approach to load/unload those and everything they have?

How do I present items? Should they be ghosts? Even if they either lie on a surface or sit in someone's hand?

How do I handle rare interactions? Levers, gates, chests -- should we use RPCs there? It doesn't seem like the best solution since this way we'll need to loop all the players to let them know a door was opened, but it definitely seems better than a ghost per door since wasting a byte per eight doors just to let everyone know the rare state change hasn't happened seems weird.

 

I wish there were lazy ghosts with no delta compression for cases where something needs its state updated on a rare basis. The ghosts that would appear/disappear on a user-defined distance condition. Something that would let an item on all the clients know it changed the state just now. Just like RPCs do, but bound to ghost entities.

 

One more moment.

We have a building with multiple doors, that have to sync their open/closed state. As far as I can understand, with Ghosts we can only have doors as prefabs, that'll need to spawn on clients, and therefore -- not initially persist there. This would mean, we need to have the doors removed from locations provided to clients, is this correct?

It would've been awesome to have pre-linked ghosts, such as doors, levers, platforms, elevators so that they weren't managing their spawn (but were managing despawn in case origin gets removed).

 

Thank you very much for the great response!

I am talking about server-side spawning/despawning. How do I stream those sectors? Not sure I understand how to use subscenes in NetCode and how to stream the data from server to clients other than via ghosts.
PVS would've been awesome if I could have my scenes as Ghosts! Sadly, there's scenes serialization confusion due to the ghosts serializer being picked by archetype rather than by actual ghost type

PVS would totally fit my needs if it'll be possible to access the ghost's entity as well as the player's one at the same time.

I think ghosts will work.

Could you, please, explain a bit how the subscenes can be used in NetCode? Or is that just a plan? Above you mentioned there's an option to stream those.

 

I managed to create ghosts for locations They all have the same ghost type, which only replicates location id and position on a client. The client then spawns the location as a child to that ghost by its index. This way, I guess, I'll be able to despawn the locations on their server-side unload. I am still not sure how to stream locations other than via ghosts.

 

@timjohansson
Hello, we are also developing Openworld game with netcode.
We also have faced similar problem, there are too many ghosts(around 6000) but almost of all ghosts are static objects like tree or stone.
We'd really like to use pre-spawned ghosts.
Do you have plan when it is released?