I have an ItemStack capability which makes an item decay over time, by storing the 'birth time' of the item to use for checks (discussed a bit more here). I'm struggling with syncing though, because ItemStack capabilities seem to be a nightmare.

 

When an ItemStack of my decaying item is first created, the server and client both make their new capability with the current world time which matches up as expected. But when an ItemStack is split or changed in some way, the server keeps its information but the client makes a new capability with a new 'birth time' of the current world time. I'm assuming this is related to all the weirdness about how Forge sends vanilla packets when capabilities change but doesn't actually update the capability (unless my information is outdated, and this problem has been solved?).

 

Anyway, my question is: where (when) should I sync my ItemStack capabilities from server to client, and how? They only need to sync when they're actually created - the 'birth time' of the stack is set when it's born and then never changes, so they don't need to be updated every tick or anything. But ItemStacks are created in so many different places, during copying, splitting, etc - I don't know how to make sure I am syncing at every possible time when it might be required. I thought about sending a packet in initCapabilities, but that method doesn't have any information about where the stack is located (inventory slot etc), so there's no way of knowing where it needs to be synced to. Can anyone advise?

ItemStack capability syncing has been discussed quite a lot in GitHub issues (e,g, here and the issues/PRs linked by it), but there's no real resolution yet.

 

One method of syncing that works fairly well is a custom IContainerListener, as described in this thread. I recently implemented this for my mod's item capabilities here. One issue with this is that an item's capability data is completely reset when taking it out of the creative menu.

Edited February 19, 20178 yr by Choonster