How should I send data from server to client on player login? I am trying to do this:

public void onEntityLoad(AttachCapabilitiesEvent.Entity event) {
        if (event.getEntity() instanceof EntityPlayer) {
            event.addCapability(new ResourceLocation(TESItems.attributesTagName), new PlayerAttributesCapabilityProvider());
            IPlayerAttributesCapability cap = event.getEntity().getCapability(TESItems.attributesCapability, null);
            networkWrapper.sendTo(new AttributesMessage(cap.getAttributes()), (EntityPlayerMP) event.getEntity());
            System.out.println("onEntityLoad(" + event.getEntity().getDisplayName() + ")");
        }

, but I get cap == null. Where should I send my packet? Capability works fine on server side, I already used it.

Capabilities are only attached and read from NBT after

AttachCapabilityEvent

has been fired. You should send the packet from

EntityJoinWorldEvent

.

 

To make the capability persist through respawning, subscribe to

PlayerEvent.Clone

and copy the capability's data from the old player to the new one.

No, it's still null. Here's my code:

@SubscribeEvent
    public void onEntityJoinWorld(EntityJoinWorldEvent event) {
        IPlayerAttributesCapability cap = event.getEntity().getCapability(TESItems.attributesCapability, null);
        if (cap == null) System.out.println("cap == null");
        networkWrapper.sendTo(new AttributesMessage(cap.getAttributes()), (EntityPlayerMP) event.getEntity());
    }

EntityJoinWorldEvent

is fired for all entities, not just players. Check if the entity is a player before trying to retrieve the capability.

 

If it still doesn't work, post your code.

There's another problem now. Minecraft#thePlayer here is null:

@Override
    public IMessage onMessage(AttributesMessage message, MessageContext ctx) {
        System.out.println("got message");
        EntityPlayer player = Minecraft.getMinecraft().thePlayer;
        if (player == null) System.out.println("player == null");
        IPlayerAttributesCapability cap = player.getCapability(TESItems.attributesCapability, null);

        for (String s : TESItems.ATTRIBUTES) {
            System.out.println("Adding " + s + " to player");
            cap.setAttribute(s, message.getAttribute(s));
        }

        return null;
    }

http://greyminecraftcoder.blogspot.com.au/2015/01/thread-safety-with-network-messages.html

 

Server entity joins world 1st, client moment after that. If you don't apply thread safety, a packet sent from join world event can reach client before client creates its player entity.

Packets are handled on a separate thread in 1.8+, so you need to schedule a task on the main thread before you can safely interact with game objects. This page explains more.

 

If scheduling a task on the main thread doesn't fix this, post your new code.

 

The client player is created and spawned when the client receives

SPacketJoinGame

from the server. The server sends this before spawning the player, so it should usually be received before a packet sent from

EntityJoinWorldEvent

.

Thanks, I just forgot about thread safety, now it's ok