Why do you level_load(NULL) when you have no level? Or do you also have a NULL level on the server?

I'm not sure I understand your question. "level_load" must be called before creating entities, even if it is a NULL level. So at the beginning of main() I call level_load(NULL), before it's determined whether the game is a client, a server, or just to play offline.

There are no other levels, and no other level_load calls except a level_load(NULL) immediately after joining a game as a client, and immediately after disconnecting as a client, because otherwise I get a "no level!" error.

Jibb

Connection to a server has nothing to do with level loading.

But when you have a level on the server, and need to synchronize your level with it, you should reload it first for resetting it to its initial state. Otherwise you might have entities in your client level that don't exist on the server. This is just a logical consequence of running a multiplayer game, and is unrelated to particular commands like session_connect. If your level is already synchronized however, I see no reason why you should want to load it again.

I don't want to, but I'm forced to, because if I don't the level gets cleared out and I get this error:...whenever I (as a client) connect, or leave.

AFAIK, level_load (which, when I'm getting these errors, only ever happens in the main function before any sessions are opened or connected) and game_load (which I never use) are the only other functions that clear out a level completely.

Jibb

No, a level can not get "cleared out" by itself. You must do this with a command. When you load a level, it stays until you load another one. The error message means not that your level is cleared out, it means that you have no level at all. When you try to remove or create entities without having a level, you'll get this error.

Maybe some sort of misconception about multiplayer or level loading is the problem here.

Okay, I'm going to try to be as clear as possible.

In the first frame, a level is loaded ("level_load(NULL)"). I can play offline, entities get created all over the place, and I enjoy myself.

Then I go back to the main menu (the level still visible in the background), load up the serverlist, and join a game.

In an instant, the level disappears, the skybox disappears, and I get this error:
Even shorter summary:
1. NULL level is loaded.
2. Create entities and interact with them to verify that there is a level.
3. Connect to online game.
4. Error because there is apparently no level when I try to create entities.

Optional steps:
5. Read the manual -- "After switching from normal to client mode with a loaded level, the level must be loaded anew." (session_connect)
6. Conclude that the manual's description is enforced by session_connect clearing out the level.
7. Work around the error by loading a NULL level again when a connection is made, and when a connection is lost (which was otherwise also causing the same problem).

Jibb

I understand the problem, but can not confirm it here. When you loaded a level before, you should not get a no level error. This would be a bug. I can connect to a server here without getting this error.

What the manual means is that you must reload the level when you have a single player level and now switch to multi player mode. The reason is simply that a single player level is very different in internal structure to a multi player level. But when you're not in single player mode, it's completely up to you if you reload the level on connection or not. At least that's the theory.

If you can't find a reason of the disappearing level, please contact the Support - they'll look into it.

Okay, please help me out here. Below is a self-contained script (no assets required), only about 40 lines long.

Please run the script, then press "s" to start a server. Leave that running and run the script again, and press "c" to connect to a server on the same machine. Here it goes black and the entity disappears (level cleared). Press "e" to create a local entity on the client, and I get the error. If I press "e" on the server (or in offline mode), another sphere is created in front of the camera.

I'm afraid I don't know why this is going wrong, and any help would be much appreciated.

Jibb

Thanks for the script! The problem here is that you're switching from single player to multi player with a single player level. So I would expect an error as soon as you connect to the server. But you're right that it should be a different error - not the "no level" error. And no error at all when you switch off entity updates completely. So there's indeed something wrong. We'll look into this and will solve the issue for the next update.

Much appreciated Thanks for your patience.

Jibb