I'm working on a mod that spawns custom entities. I spawn an entity by constructing it and calling world.spawnEntity(). I wanted to give my entities unique names and in doing so I discovered that the constructor is actually being called twice. If I modify the parameters of the constructor, I get an exception that traces back to:

 

net.minecraftforge.fml.common.network.internal.EntitySpawnHandler.spawnEntity(EntitySpawnHandler.java:144)

 

What confused me even more is that even if the constructor isn't called a second time, the entity can still carry out actions but it will be invisible. Does the client construct a client for logic and visuals? Is there a way I can ensure that only one entity is constructed? Thanks! 

 

edit: Apparently not a problem when WorldClient spawns the entity, although still not sure why!

Edited February 12, 20178 yr by Coron

It spawns once on the server thread and once on the client thread.

 

What's so hard about understanding that?  If the threads are running on different machines (cough, dedicated server, cough) what did you expect to happen?

9 minutes ago, Draco18s said:

What's so hard about understanding that?  If the threads are running on different machines (cough, dedicated server, cough) what did you expect to happen?

Makes sense. I've been working with modding/Forge for less than 24h, so I really had no idea  Do the instances share any identifiers across the sides?

Edited February 12, 20178 yr by Coron

No.  They share data through packets.

Client-Server architecture takes a few knocks to wrap one's head around, especially when Eclipse runs both on a single machine sharing a single JRE.

 

For most classes and their constructors, it doesn't matter. If yours is coughing up a lung (and it's not an obvious rendering action crashing the server), then start wrapping your head...

 

Look into the way that vanilla entities spawn. See how the dance  is done so that the server makes decisions and the client follows its lead (an entity's image is on the client, but its soul is on the server). Usually, if your mod operates at the right level of abstraction, the client-server interaction (messages etc) are handled for you. If you happened to discover a class or method that looked useful but is down in the weeds, then you might accidentally be short-circuiting the process.