(solved) [1.16] setInventorySlotContents(), but on the server side

[FluffyDiscord]

Hello,

I would like to make a mod, where player can swap items he is holding when he scrolls with mouse wheel and holds the right item from a predefined list in hand. So far I have made a prototype which works - kinda - it switches items on the client side as I understand this correctly.

 

My question is, how do I send the item swap request to the server to validate (if it's a valid swap request) and then update player's inventory according to it ?

 

I have found this page https://mcforge.readthedocs.io/en/1.15.x/networking/simpleimpl/ but I am kinda confused - what do I do with that information ?

 

package com.mossshine.blocks.init;

import net.minecraft.client.Minecraft;
import net.minecraft.client.entity.player.ClientPlayerEntity;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraftforge.api.distmarker.Dist;
import net.minecraftforge.client.event.InputEvent;
import net.minecraftforge.eventbus.api.SubscribeEvent;
import net.minecraftforge.fml.common.Mod;

@Mod.EventBusSubscriber(Dist.CLIENT)
public class Events {

    private static final double SCROLL_DOWN = -1.0;
    private static final double SCROLL_UP = 1.0;

    @SubscribeEvent
    public static void mouseScrolled(InputEvent.MouseScrollEvent event) {
        ClientPlayerEntity player = Minecraft.getInstance().player;
        if (player != null) {
            ItemStack currentItem = player.getHeldItemMainhand();
            int index = BlocksList.LOG_ARRAY_LIST.indexOf(currentItem.getItem());

            if (event.getScrollDelta() == SCROLL_DOWN && index != -1) {
                event.setCanceled(true);
                int slot = player.inventory.currentItem;
                Item prevItem;

                index--;
                if (index > -1) {
                    prevItem = BlocksList.LOG_ARRAY_LIST.get(index);
                } else {
                    prevItem = BlocksList.LOG_ARRAY_LIST.get(BlocksList.LOG_ARRAY_LIST.size() - 1);
                }
                ItemStack newItem = new ItemStack(prevItem, currentItem.getCount());

                player.inventory.setInventorySlotContents(slot, newItem);
                player.container.detectAndSendChanges();
            }
        }
    }
}

 

Edited September 20, 2020 by FluffyDiscord

[diesieben07]

If you want this to be a purely client-side mod you need to look at the ContainerScreen class and how it handles clicking on containers. You then need to replicate those actions to make the server think that the player moved the items.

[FluffyDiscord]

No this definitely should be server sided too. I got it figured out eventually with the packet system. I was just confused with creating some class that would be sending and receiving my packets. Can I somehow mark this issue as solved ?

[diesieben07]

You can edit the title.

Just note that if you have the client control something like this you need to be careful to avoid exploits.

In your case I would only send "player scrolled X amount", not e.g. "move stack A from A to B".

[Alpvax]

On 9/20/2020 at 6:16 PM, diesieben07 said:

In your case I would only send "player scrolled X amount", not e.g. "move stack A from A to B".

I'm not fully convinced of that. You should send "player scrolled X slots", that way the actual scroll amount per slot can be configured client-side.

[diesieben07]

8 minutes ago, Alpvax said:

I'm not fully convinced of that. You should send "player scrolled X slots", that way the actual scroll amount per slot can be configured client-side.

Yes, that is what I meant.