Add Hopper Sorting

[AsaAyers]

A hopper with a sign attached would cause that hopper to only pick up things that are on the list.

[AsaAyers]

I started looking into how to do this, but I've only done small amounts of hacking on this plugin. If you have any advice on how to get started, or where to find good docs it would be much appreciated.

[ylt]

Haven't looked into Hoppers, will have a look how they work and find out the easiest method of adding them.

[AsaAyers]

From what I know, the bottom hopper gets a chance to pull an item down before the upper hopper is allowed to push the item horizontally. It seems like onInventoryPickupItemEvent should work and if the hopper picking up the item doesn't accept it, cancel it. The main thing I don't know is how to get all the way from the event, to getting the block of the hopper to examine any potentially attached signs.

I wrote a couple lines of code, but don't have anything near runnable yet.

[ylt]

Quite a few different methods of using it, so may not work in every instance - have had a bit of a look:
https://github.com/Bukkit/CraftBukkit/blob/master/src/main/java/net/minecraft/server/TileEntityHopper.java#L244

Looks like it is possible to control what items it takes out of inventories using InventoryMoveItemEvent, but not picking up items.

[ylt]

Actually.. yeah.. can be done with InventoryPickupItemEvent as well

[ylt]

InventoryMoveItemEvent event = new InventoryMoveItemEvent(sourceInventory, oitemstack.clone(), ihopper.getOwner().getInventory(), false);

InventoryPickupItemEvent event = new InventoryPickupItemEvent(iinventory.getOwner().getInventory(), (org.bukkit.entity.Item) entityitem.getBukkitEntity());

Bit confused about the parameters, unsure about the inventory - which inventory it's referring to AND if it will be possible to follow the inventory object back to the hopper.

Other related classes:
Bukkit:
https://github.com/Bukkit/CraftBukkit/blob/master/src/main/java/net/minecraft/server/BlockHopper.java
https://github.com/Bukkit/CraftBukkit/blob/master/src/main/java/net/minecraft/server/ContainerHopper.java
https://github.com/Bukkit/CraftBukkit/blob/master/src/main/java/net/minecraft/server/TileEntityHopper.java

Mc-dev:
https://github.com/Bukkit/mc-dev/blob/master/net/minecraft/server/EntityMinecartHopper.java
https://github.com/Bukkit/mc-dev/blob/master/net/minecraft/server/IHopper.java

[ylt]

Can't find at a glance where the inventory is coming from, need to do a proper search later.. will clone the repo and do some greps later when I get the time..

At the moment, not sure what type of inventory it is - if we're lucky it'll contain a block/location reference.. if not, we'll have to keep our own mapping of inventories->blocks (maybe on physics event or something)

[AsaAyers]

Wow! thanks for all the info. When I get some time this is enough for me to experiment with.

If you get to it first 👍 and I'll be watching the repo to see how you end up implementing it.

[ylt]

Looks like you can't directly follow the inventory back to its block.. but had an idea, if it's the pickup event; it should be possible to guess which hopper based on its location.. can just scan the surrounding blocks..

Just means possibly having inaccurate results if multiple hoppers are near
Just realised.. we have the inventory object, we can just scan for hoppers containing that inventory rather than just a hopper that's facing the item.