jos_valentin•2d ago

Clients and spawn points

What would be a good approach for this case: When the clients connect, I want to spawn them in specific positions that are stored in an array of transforms, so to have control of it I imagine that the first player must have the ownership of this container with the index in the respective model. The thing is that each player spawns themself also but they cant try to take an spawn point since could be a raise condition (When an spawn point is used, the index is changed) son 2 players can be spawned at the same spawn point. Would it be good to use an RPC in this case? So the owner of the spawn points send an Spawn event with the target point position for a player?

6 Replies

kapa.ai•2d ago

Hi @jos_valentin. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave: ---------------------- Your question about managing spawn points for multiple clients in NormalVR is a common multiplayer challenge. Based on the knowledge sources, I can suggest a good approach for this scenario. Managing Spawn Points with Ownership Instead of using RPCs (which Normcore generally discourages), a better approach would be to use Normcore's ownership system combined with a synchronized collection to manage spawn points. Why Not Use RPCs? Normcore explicitly warns against using RPC messages:

"Before we dive into this recipe, I'd like to warn you against using RPC messages... We believe this is a bad pattern. It puts the burden on you, the developer, to ensure that all state that is changed in response to an RPC message remains in sync across all clients." RPC Events

Recommended Approach 1. Create a Spawn Manager Component: Make a custom RealtimeComponent that manages spawn points. 2. Use a StringKeyDictionary or RealtimeDictionary: These collections are designed to handle concurrent modifications safely:

"Transactional collections do not reflect a change to the collection until the server has confirmed the change. They also reject your change if another client has modified the same key before your change is received by the server." Collections

3. Ownership Control: Have the first client take ownership of the spawn manager:

   // On the spawn manager component
   if (realtime.clientID == /* check if first client */) {
       RequestOwnership();
   }

   // On the spawn manager component
   if (realtime.clientID == /* check if first client */) {
       RequestOwnership();
   }

4. Spawn Point Assignment: When a new player joins, they can request a spawn point from the manager, which will assign one and mark it as used in the synchronized collection. 5. Prevent Ownership Takeover: Use the preventOwnershipTakeover flag to ensure only the designated client can manage spawn points:

"When this flag is true on any model, the server will deny any client's attempt to change the ownership of an object in that model unless it has no owner." Prevent Ownership Takeover

This approach leverages Normcore's built-in synchronization and ownership systems to handle the race condition you're concerned about, without resorting to RPCs which can lead to synchronization issues. For player spawning, you could use the RealtimeAvatarManager which is designed to handle avatar instantiation, and customize it to use your spawn point system. ---------------------- Note: you can ask me a follow up question by @ mentioning me again :speech_balloon: ----------------------

kapa.ai•2d ago

<@391444583034257420> Kapa.ai is still learning and improving, please let me know how I did by reacting below.

jos_valentinOP•2d ago

I dont know how I am suppose to implement the 4. step which is the important one

Mechabit•2d ago

easiest method is to use the client id as spawn point index

jos_valentinOP•2d ago

Sounds good for what I am traying to do! In case I dont want to depend of the client id, the approeach with an rpc would be a good idea?

Mechabit•2d ago

RPC doesn't work for late joiners, safer to sync the spawn point ID as an int on the avatar

Clients and spawn points

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