[1.15.2] Custom Entity Container/Gui Not Interactable

[OuiOuiCroissant]

I am trying to create an entity with a gui that displays slots for their armor, mainhand, offhand, and a 10 slot inventory. Currently my gui will open when the entity is right-clicked by the player, but it is unfortunately NOT interactable.

 

Entity Super Class - SiegeEntity:

Spoiler

package com.siegemod.entities;

import com.siegemod.container.PeasantContainer;

import net.minecraft.entity.AgeableEntity;
import net.minecraft.entity.Entity;
import net.minecraft.entity.EntityType;
import net.minecraft.entity.ILivingEntityData;
import net.minecraft.entity.SharedMonsterAttributes;
import net.minecraft.entity.SpawnReason;
import net.minecraft.entity.ai.goal.HurtByTargetGoal;
import net.minecraft.entity.ai.goal.LookAtGoal;
import net.minecraft.entity.ai.goal.LookRandomlyGoal;
import net.minecraft.entity.ai.goal.MoveThroughVillageGoal;
import net.minecraft.entity.ai.goal.MoveTowardsVillageGoal;
import net.minecraft.entity.ai.goal.SwimGoal;
import net.minecraft.entity.ai.goal.WaterAvoidingRandomWalkingGoal;
import net.minecraft.entity.merchant.villager.AbstractVillagerEntity;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.entity.player.ServerPlayerEntity;
import net.minecraft.inventory.container.Container;
import net.minecraft.inventory.container.INamedContainerProvider;
import net.minecraft.item.ItemStack;
import net.minecraft.item.MerchantOffer;
import net.minecraft.nbt.CompoundNBT;
import net.minecraft.util.Hand;
import net.minecraft.util.math.BlockPos;
import net.minecraft.util.text.ITextComponent;
import net.minecraft.world.DifficultyInstance;
import net.minecraft.world.IWorld;
import net.minecraft.world.World;
import net.minecraftforge.fml.network.NetworkHooks;

public abstract class SiegeEntity extends AbstractVillagerEntity {

    protected final double WALK_SPEED = 0.4D;
    // Convert to ItemHandler
    //private final Inventory PEASANT_INVENTORY = new Inventory(16);

    // 0 = wander, 1 = follow, 2 = locked follow, 3 = guard, 4 = locked guard.
    protected double stance = 0;
    protected PlayerEntity king;
    protected PlayerEntity[] allies;

    protected BlockPos bedPosition;
    protected BlockPos destination;
    protected ItemStack targetItem;

    public SiegeEntity(EntityType<? extends AbstractVillagerEntity> entityType, World worldIn, PlayerEntity kingIn) {
        super(entityType, worldIn);
        // this.king = kingIn;
    }

    @Override
    protected void registerGoals() {
        this.goalSelector.addGoal(0, new SwimGoal(this));
        // We're going to need a custom avoid entity goal
        // We're going to need a custom choose target goal
        this.goalSelector.addGoal(3, new MoveTowardsVillageGoal(this, WALK_SPEED));
        this.goalSelector.addGoal(3, new MoveThroughVillageGoal(this, WALK_SPEED, false, 4, () -> {
            return true;
        }));
        this.goalSelector.addGoal(6, new WaterAvoidingRandomWalkingGoal(this, WALK_SPEED));
        this.goalSelector.addGoal(7, new LookAtGoal(this, PlayerEntity.class, 6.0F));
        this.goalSelector.addGoal(8, new LookRandomlyGoal(this));

        this.targetSelector.addGoal(2, new HurtByTargetGoal(this));
    }

    @Override
    protected void registerAttributes() {
        super.registerAttributes();
        this.getAttribute(SharedMonsterAttributes.MAX_HEALTH).setBaseValue(20.0D);
        this.getAttribute(SharedMonsterAttributes.FOLLOW_RANGE).setBaseValue(64.0D);
        this.getAttribute(SharedMonsterAttributes.MOVEMENT_SPEED).setBaseValue(0.6F);

        this.getAttributes().registerAttribute(SharedMonsterAttributes.ATTACK_DAMAGE).setBaseValue(1.0D);

        this.getAttribute(SharedMonsterAttributes.ARMOR).setBaseValue(0.0D);
        this.getAttribute(SharedMonsterAttributes.ARMOR_TOUGHNESS).setBaseValue(0.0D);
        this.getAttribute(SharedMonsterAttributes.KNOCKBACK_RESISTANCE).setBaseValue(10.0F);
    }

    @Override
    public boolean attackEntityAsMob(Entity entityIn) {
        this.swingArm(getActiveHand());
        return super.attackEntityAsMob(entityIn);
    }

    public void livingTick() {
        this.updateArmSwingProgress();
        super.livingTick();
    }

    @Override
    public ILivingEntityData onInitialSpawn(IWorld worldIn, DifficultyInstance difficultyIn, SpawnReason reason, ILivingEntityData spawnDataIn, CompoundNBT dataTag) {
        // Temporary method of choosing king. Implement join kingdom feature in future.
        if (reason == SpawnReason.COMMAND) {
            this.king = world.getClosestPlayer(this.getPosX(), this.getPosY(), this.getPosZ(), 64, false);
        }
        return super.onInitialSpawn(worldIn, difficultyIn, reason, spawnDataIn, dataTag);
    }

    @Override
    public void writeAdditional(CompoundNBT compound) {
        super.writeAdditional(compound);
    }

    @Override
    public void readAdditional(CompoundNBT compound) {
        super.readAdditional(compound);
    }

    public PlayerEntity getKing() {
        return king;
    }

    @Override
    public AgeableEntity createChild(AgeableEntity ageable) {
        return null;
    }

    @Override
    protected void onVillagerTrade(MerchantOffer offer) {
    }

    @Override
    protected void populateTradeData() {
    }

    @Override
    public final boolean processInteract(PlayerEntity player, Hand hand) {
        if (hand == Hand.MAIN_HAND) {
            if (getKing() == null) {
                // Open join kingdom request screen.
                // OpenGui only accepts ServerPlayerEntity
                // Also works to ensure we are serverside
                System.out.println("king is null");
            } else if (player == getKing() && player instanceof ServerPlayerEntity) {
                System.out.println("king is " + player.toString());
                NetworkHooks.openGui((ServerPlayerEntity) player, new SiegeContainerProvider(this));
                return true;
            }
        }
        return super.processInteract(player, hand);
    }

    public static class SiegeContainerProvider implements INamedContainerProvider {

        private final SiegeEntity PEASANT;

        public SiegeContainerProvider(SiegeEntity peasantIn) {
            this.PEASANT = peasantIn;
        }

        @Override
        public Container createMenu(int containerId, PlayerInventory playerInv, PlayerEntity player) {
            return new PeasantContainer(player, PEASANT);
        }

        @Override
        public ITextComponent getDisplayName() {
            return PEASANT.getDisplayName();
        }
    }
}

Entity Class - PeasantEntity:

Spoiler

package com.siegemod.entities.friendly;

import com.siegemod.entities.SiegeEntity;
import com.siegemod.entities.enemy.EnemyEntity;

import net.minecraft.entity.EntityType;
import net.minecraft.entity.ai.goal.AvoidEntityGoal;
import net.minecraft.entity.merchant.villager.AbstractVillagerEntity;
import net.minecraft.entity.monster.ZombieEntity;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.world.World;

public class PeasantEntity extends SiegeEntity {

    public PeasantEntity(EntityType<? extends AbstractVillagerEntity> entityType, World worldIn) {
        this(entityType, worldIn, null);
    }

    public PeasantEntity(EntityType<? extends AbstractVillagerEntity> entityType, World worldIn, PlayerEntity kingIn) {
        super(entityType, worldIn, kingIn);
    }

    @Override
    protected void registerGoals() {
        this.goalSelector.addGoal(2, new AvoidEntityGoal<>(this, EnemyEntity.class, 16.0F, WALK_SPEED, WALK_SPEED * 1.2D));
        this.goalSelector.addGoal(2, new AvoidEntityGoal<>(this, ZombieEntity.class, 16.0F, WALK_SPEED, WALK_SPEED * 1.2D));
    }
}

Container Class:

Spoiler

package com.siegemod.container;

import com.siegemod.entities.SiegeEntity;

import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.inventory.Inventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.inventory.container.Slot;
import net.minecraft.item.ItemStack;
import net.minecraft.network.PacketBuffer;

public class PeasantContainer extends Container {

    public SiegeEntity peasant;
    public Inventory peasantInventory;

    public PeasantContainer(int containerId, PlayerInventory playerInv, PacketBuffer containerBuffer) {
        super(SiegeContainerTypes.PEASANT_CONTAINER.get(), containerId);
    }

    public PeasantContainer(PlayerEntity player, SiegeEntity peasantIn) {
        super(SiegeContainerTypes.PEASANT_CONTAINER.get(), 0);
        // replace with ItemHandler in future
        this.peasantInventory = new Inventory(16); //peasantInventory.getPeasantInventory.getInv();
        assertInventorySize(peasantInventory, 16);
        this.peasant = peasantIn;
        /*
        // Armor Inventory
        int armorInvYPos = 8;
        int sizePerSlot = 18;
        for (int column = 0; column < 4; ++column) {
            this.addSlot(new Slot(this.peasantInventory, 4, 8, armorInvYPos + (column * sizePerSlot)));
        }
        
        // MainHand
        this.addSlot(new Slot(this.peasantInventory, 4, 32, 62));
        
        // OffHand
        this.addSlot(new Slot(this.peasantInventory, 5, 32, 62));
        
        // Main Inventory
        int invXPos = 80;
        int invYPos = 8;
        int slotsInEachRow = 5;
        for (int row = 0; row < 5; ++row) {
            for (int column = 0; column < 4; ++column) {
                this.addSlot(new Slot(this.peasantInventory, row + column * slotsInEachRow + 6, invXPos + (column * sizePerSlot), invYPos + (row * sizePerSlot)));
            }
        }*/
        // Temporary layout
        //ARMOR
        this.addSlot(new Slot(this.peasantInventory, 0, 8, 8));
        this.addSlot(new Slot(this.peasantInventory, 1, 8, 26));
        this.addSlot(new Slot(this.peasantInventory, 2, 8, 44));
        this.addSlot(new Slot(this.peasantInventory, 3, 8, 62));
        //MAINHAND & OFFHAND
        this.addSlot(new Slot(this.peasantInventory, 4, 32, 62));
        this.addSlot(new Slot(this.peasantInventory, 5, 56, 62));
        //MAIN
        this.addSlot(new Slot(this.peasantInventory, 6, 80, 8));
        this.addSlot(new Slot(this.peasantInventory, 7, 98, 8));
        this.addSlot(new Slot(this.peasantInventory, 8, 116, 8));
        this.addSlot(new Slot(this.peasantInventory, 9, 134, 8));
        this.addSlot(new Slot(this.peasantInventory, 10, 152, 8));
        this.addSlot(new Slot(this.peasantInventory, 11, 80, 26));
        this.addSlot(new Slot(this.peasantInventory, 12, 98, 26));
        this.addSlot(new Slot(this.peasantInventory, 13, 116, 26));
        this.addSlot(new Slot(this.peasantInventory, 14, 134, 26));
        this.addSlot(new Slot(this.peasantInventory, 15, 152, 26));

        // Player Main Inventory
        for (int row = 0; row < 3; ++row) {
            for (int column = 0; column < 9; ++column) {
                this.addSlot(new Slot(player.inventory, column + row * 9 + 9, 8 + column * 18, 102 + row * 18 + -18));
            }
        }
        // Player Hotbar
        for (int row = 0; row < 9; ++row) {
            this.addSlot(new Slot(player.inventory, row, 8 + row * 18, 142));
        }
    }

    @Override
    public boolean canInteractWith(PlayerEntity playerIn) {
        return true;// peasant != null && playerIn.getDistance(peasant) <= PlayerEntity.REACH_DISTANCE.getDefaultValue() + 1;
    }

    public ItemStack transferStackInSlot(PlayerEntity playerIn, int index) {
        ItemStack itemstack = ItemStack.EMPTY;
        Slot slot = this.inventorySlots.get(index);
        if (slot != null && slot.getHasStack()) {
            ItemStack itemstack1 = slot.getStack();
            itemstack = itemstack1.copy();
            if (index < this.peasantInventory.getSizeInventory()) {
                if (!this.mergeItemStack(itemstack1, this.peasantInventory.getSizeInventory(), this.inventorySlots.size(), true)) {
                    return ItemStack.EMPTY;
                }
            } else if (!this.mergeItemStack(itemstack1, 0, this.peasantInventory.getSizeInventory(), false)) {
                return ItemStack.EMPTY;
            }

            if (itemstack1.isEmpty()) {
                slot.putStack(ItemStack.EMPTY);
            } else {
                slot.onSlotChanged();
            }
        }

        return itemstack;
    }

    public SiegeEntity getPeasant() {
        return this.peasant;
    }
}

Container Screen Class:

Spoiler

package com.siegemod.container;

import com.mojang.blaze3d.systems.RenderSystem;
import com.siegemod.SiegeMod;

import net.minecraft.client.gui.screen.inventory.ContainerScreen;
import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.util.ResourceLocation;
import net.minecraft.util.text.ITextComponent;
import net.minecraftforge.api.distmarker.Dist;
import net.minecraftforge.api.distmarker.OnlyIn;

@OnlyIn(Dist.CLIENT)
public class PeasantScreen extends ContainerScreen<PeasantContainer> {

    private static final ResourceLocation PEASANT_GUI = new ResourceLocation(SiegeMod.MODID, "gui/peasant_gui.png");

    public PeasantScreen(PeasantContainer screenContainer, PlayerInventory inv, ITextComponent titleIn) {
        super(screenContainer, inv, titleIn);
        this.guiLeft = 0;
        this.guiTop = 0;
        this.xSize = 176;
        this.ySize = 166;
    }

    @Override
    protected void init() {
        super.init();
    }

    @Override
    protected void drawGuiContainerBackgroundLayer(float partialTicks, int mouseX, int mouseY) {
        RenderSystem.color4f(1.0F, 1.0F, 1.0F, 1.0F);
        this.getMinecraft().getTextureManager().bindTexture(PEASANT_GUI);
        int x = (this.width - this.xSize) / 2;
        int y = (this.height - this.ySize) / 2;
        this.blit(x, y, 0, 0, this.xSize, this.ySize);
    }

    @Override
    public void render(int mouseX, int mouseY, float partialTicks) {
        this.renderBackground();
        super.render(mouseX, mouseY, partialTicks);
        this.renderHoveredToolTip(mouseX, mouseY);
    }
}

ContainerTypes Class:

Spoiler

package com.siegemod.container;

import com.siegemod.SiegeMod;

import net.minecraft.inventory.container.ContainerType;
import net.minecraftforge.common.extensions.IForgeContainerType;
import net.minecraftforge.fml.RegistryObject;
import net.minecraftforge.registries.DeferredRegister;
import net.minecraftforge.registries.ForgeRegistries;

public class SiegeContainerTypes {

    public static final DeferredRegister<ContainerType<?>> CONTAINER_TYPES = new DeferredRegister<>(ForgeRegistries.CONTAINERS, SiegeMod.MODID);

    public static final RegistryObject<ContainerType<PeasantContainer>> PEASANT_CONTAINER = CONTAINER_TYPES.register(SiegeMod.MODID, () -> {
        return IForgeContainerType.create(PeasantContainer::new);
    });
}

ClientEventBusSubscriber:

Spoiler

package com.siegemod.util;

import com.siegemod.SiegeMod;
import com.siegemod.container.PeasantScreen;
import com.siegemod.container.SiegeContainerTypes;
import com.siegemod.entities.SiegeEntityTypes;
import com.siegemod.entities.render.PeasantRenderer;

import net.minecraft.client.gui.ScreenManager;
import net.minecraftforge.api.distmarker.Dist;
import net.minecraftforge.eventbus.api.SubscribeEvent;
import net.minecraftforge.fml.client.registry.RenderingRegistry;
import net.minecraftforge.fml.common.Mod;
import net.minecraftforge.fml.common.Mod.EventBusSubscriber.Bus;
import net.minecraftforge.fml.event.lifecycle.FMLClientSetupEvent;

@Mod.EventBusSubscriber(modid = SiegeMod.MODID, bus = Bus.MOD, value = Dist.CLIENT)
public class ClientEventBusSubscriber {

    @SubscribeEvent
    public static void clientSetup(FMLClientSetupEvent event) {

        ScreenManager.registerFactory(SiegeContainerTypes.PEASANT_CONTAINER.get(), PeasantScreen::new);

        RenderingRegistry.registerEntityRenderingHandler(SiegeEntityTypes.PEASANT.get(), PeasantRenderer::new);
    }
}

Main Class:

Spoiler

package com.siegemod;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import com.siegemod.container.SiegeContainerTypes;
import com.siegemod.entities.SiegeEntityTypes;

import net.minecraft.client.Minecraft;
import net.minecraftforge.common.MinecraftForge;
import net.minecraftforge.eventbus.api.IEventBus;
import net.minecraftforge.eventbus.api.SubscribeEvent;
import net.minecraftforge.fml.common.Mod;
import net.minecraftforge.fml.event.lifecycle.FMLClientSetupEvent;
import net.minecraftforge.fml.event.lifecycle.FMLCommonSetupEvent;
import net.minecraftforge.fml.event.server.FMLServerStartingEvent;
import net.minecraftforge.fml.javafmlmod.FMLJavaModLoadingContext;

@Mod("siegemod")
public class SiegeMod {
    // this is what you'll use to output anything to the log (instead of sysout if
    // you like)
    public static final Logger LOGGER = LogManager.getLogger();
    public static final String MODID = "siegemod";
    public static SiegeMod instance;
    public static Minecraft mc = Minecraft.getInstance();

    public SiegeMod() {
        final IEventBus modEventBus = FMLJavaModLoadingContext.get().getModEventBus();

        instance = this;

        FMLJavaModLoadingContext.get().getModEventBus().addListener(this::setup);
        FMLJavaModLoadingContext.get().getModEventBus().addListener(this::doClientStuff);

        MinecraftForge.EVENT_BUS.register(this);

        SiegeEntityTypes.ENTITY_TYPES.register(modEventBus);
        SiegeContainerTypes.CONTAINER_TYPES.register(modEventBus);
    }

    private void setup(final FMLCommonSetupEvent event) {

    }

    private void doClientStuff(final FMLClientSetupEvent event) {

    }

    @SubscribeEvent
    public void onServerStarting(FMLServerStartingEvent event) {

    }

    // You can use EventBusSubscriber to automatically subscribe events on the
    // contained class (this is subscribing to the MOD
    // Event bus for receiving Registry Events)
    @Mod.EventBusSubscriber(bus = Mod.EventBusSubscriber.Bus.MOD)
    public static class RegistryEvents {
    }
}

I will be converting from Inventory to ItemHandler soon, but for now I just want the container to open.

 

--SOLUTION--

Main Entity Class:

Spoiler

package com.siegemod.entities;

import java.util.UUID;
import java.util.function.Consumer;

import com.siegemod.container.PeasantContainer;
import com.siegemod.container.PeasantInventory;

import net.minecraft.entity.AgeableEntity;
import net.minecraft.entity.Entity;
import net.minecraft.entity.EntityType;
import net.minecraft.entity.ILivingEntityData;
import net.minecraft.entity.SharedMonsterAttributes;
import net.minecraft.entity.SpawnReason;
import net.minecraft.entity.ai.goal.HurtByTargetGoal;
import net.minecraft.entity.ai.goal.LookAtGoal;
import net.minecraft.entity.ai.goal.LookRandomlyGoal;
import net.minecraft.entity.ai.goal.MoveThroughVillageGoal;
import net.minecraft.entity.ai.goal.MoveTowardsTargetGoal;
import net.minecraft.entity.ai.goal.MoveTowardsVillageGoal;
import net.minecraft.entity.ai.goal.SwimGoal;
import net.minecraft.entity.merchant.villager.AbstractVillagerEntity;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.entity.player.ServerPlayerEntity;
import net.minecraft.inventory.Inventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.inventory.container.INamedContainerProvider;
import net.minecraft.item.ItemStack;
import net.minecraft.item.MerchantOffer;
import net.minecraft.nbt.CompoundNBT;
import net.minecraft.nbt.ListNBT;
import net.minecraft.network.PacketBuffer;
import net.minecraft.pathfinding.GroundPathNavigator;
import net.minecraft.util.Hand;
import net.minecraft.util.math.BlockPos;
import net.minecraft.util.text.ITextComponent;
import net.minecraft.world.DifficultyInstance;
import net.minecraft.world.IWorld;
import net.minecraft.world.World;
import net.minecraftforge.fml.network.NetworkHooks;

public abstract class SiegeEntity extends AbstractVillagerEntity {
    private final PeasantInventory peasantInventory;
    private final SiegeEntityInventoryContainerProvider containerProvider;
    public SiegeEntity(EntityType<? extends AbstractVillagerEntity> entityType, World worldIn, PlayerEntity kingIn) {
        super(entityType, worldIn);
        this.peasantInventory = new PeasantInventory(new Inventory(16), this);
        this.containerProvider = new SiegeEntityInventoryContainerProvider(this);
    }
    @Override
    public final boolean processInteract(PlayerEntity player, Hand hand) {
        if (hand == Hand.MAIN_HAND && player instanceof ServerPlayerEntity && !world.isRemote) {
                SiegeEntity peasant = this;
                NetworkHooks.openGui((ServerPlayerEntity) player, this.containerProvider, new Consumer<PacketBuffer>() {
                    @Override
                    public void accept(PacketBuffer buffer) {
                        buffer.writeInt(peasant.getEntityId());
                    }
                });
                return true;
        }
        return super.processInteract(player, hand);
    }

    @Override
    public void writeAdditional(CompoundNBT compound) {
        super.writeAdditional(compound);
        ListNBT listnbt = new ListNBT();
        for (int i = 0; i < this.peasantInventory.getSlots(); ++i) {
            ItemStack itemstack = this.peasantInventory.getStackInSlot(i);
            if (!itemstack.isEmpty()) {
                listnbt.add(itemstack.write(new CompoundNBT()));
            }
        }
        compound.put("PeasantInventory", listnbt);
    }

    @Override
    public void readAdditional(CompoundNBT compound) {
        super.readAdditional(compound);

        ListNBT listnbt = compound.getList("PeasantInventory", 10);
        for (int i = 0; i < listnbt.size(); ++i) {
            ItemStack itemstack = ItemStack.read(listnbt.getCompound(i));
            if (!itemstack.isEmpty()) {
                this.peasantInventory.insertItem(i, itemstack, false);
            }
        }
    }

    public PeasantInventory getPeasantInventory() {
        return peasantInventory;
    }

    public class SiegeEntityInventoryContainerProvider implements INamedContainerProvider {

        private final SiegeEntity peasant;

        public SiegeEntityInventoryContainerProvider(SiegeEntity peasantIn) {
            this.peasant = peasantIn;
        }

        @Override
        public Container createMenu(int containerId, PlayerInventory playerInv, PlayerEntity player) {
            return new PeasantContainer(containerId, playerInv, this.peasant);
        }

        @Override
        public ITextComponent getDisplayName() {
            return peasant.getDisplayName();
        }
    }

ContainerFactory:

Spoiler

package com.siegemod.util;

import com.siegemod.container.PeasantContainer;

import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.network.PacketBuffer;
import net.minecraftforge.fml.network.IContainerFactory;

public class SiegeContainerFactory implements IContainerFactory<Container> {

    @Override
    public Container create(int windowId, PlayerInventory inv, PacketBuffer data) {
        return new PeasantContainer(windowId, inv, data);
    }
}

ScreenFactory:

Spoiler

package com.siegemod.util;

import com.siegemod.container.PeasantScreen;

import net.minecraft.client.gui.ScreenManager.IScreenFactory;
import net.minecraft.client.gui.screen.inventory.ContainerScreen;
import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.util.text.ITextComponent;

public class SiegeScreenFactory implements IScreenFactory<Container, ContainerScreen<Container>> {

    @Override
    public ContainerScreen<Container> create(Container container, PlayerInventory inv, ITextComponent ITextComponent) {
        return new PeasantScreen(container, inv, ITextComponent);
    }
}

Container Class:

Spoiler

package com.siegemod.container;

import com.mojang.datafixers.util.Pair;
import com.siegemod.entities.SiegeEntity;

import net.minecraft.enchantment.EnchantmentHelper;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.inventory.EquipmentSlotType;
import net.minecraft.inventory.IInventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.inventory.container.PlayerContainer;
import net.minecraft.inventory.container.Slot;
import net.minecraft.item.ItemStack;
import net.minecraft.network.PacketBuffer;
import net.minecraft.util.ResourceLocation;
import net.minecraftforge.api.distmarker.Dist;
import net.minecraftforge.api.distmarker.OnlyIn;

public class PeasantContainer extends Container {

    public SiegeEntity peasant;
    public IInventory peasantInventory;

    public PeasantContainer(int containerId, PlayerInventory playerInv, PacketBuffer containerBuffer) {
        this(containerId, playerInv, (SiegeEntity) playerInv.player.world.getEntityByID(containerBuffer.readInt()));
    }

    public PeasantContainer(int containerId, PlayerInventory playerInv, SiegeEntity peasantIn) {
        super(SiegeContainerTypes.PEASANT_CONTAINER.get(), containerId);
        this.peasant = peasantIn;
        this.peasantInventory = peasant.getPeasantInventory().getInv();
        this.peasantInventory.openInventory(playerInv.player);

 

        // Entity Slots

 

        // Player Main Inventory
        for (int row = 0; row < 3; ++row)
            for (int column = 0; column < 9; ++column)
                this.addSlot(new Slot(playerInv, column + row * 9 + 9, 8 + column * 18, 102 + row * 18 + -18));

        // Player Hotbar
        for (int row = 0; row < 9; ++row) {
            this.addSlot(new Slot(playerInv, row, 8 + row * 18, 142));
        }
    }

    @Override
    public boolean canInteractWith(PlayerEntity playerIn) {
        return true;
    }

    @Override
    public ItemStack transferStackInSlot(PlayerEntity playerIn, int index) {
        ItemStack itemstack = ItemStack.EMPTY;
        Slot slot = this.inventorySlots.get(index);
        if (slot != null && slot.getHasStack()) {
            ItemStack itemstack1 = slot.getStack();
            itemstack = itemstack1.copy();
            if (index < this.peasantInventory.getSizeInventory()) {
                if (!this.mergeItemStack(itemstack1, this.peasantInventory.getSizeInventory(), this.inventorySlots.size(), true)) {
                    return ItemStack.EMPTY;
                }
            } else if (!this.mergeItemStack(itemstack1, 1, this.peasantInventory.getSizeInventory(), false)) {
                return ItemStack.EMPTY;
            }
            if (itemstack1.isEmpty()) {
                slot.putStack(ItemStack.EMPTY);
            } else {
                slot.onSlotChanged();
            }
        }
        return itemstack;
    }

    public SiegeEntity getPeasant() {
        return this.peasant;
    }
}

Screen Class:

Spoiler

package com.siegemod.container;

import com.mojang.blaze3d.systems.RenderSystem;
import com.siegemod.SiegeMod;
import com.siegemod.entities.SiegeEntity;

import net.minecraft.client.gui.screen.inventory.ContainerScreen;
import net.minecraft.client.gui.screen.inventory.InventoryScreen;
import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.util.ResourceLocation;
import net.minecraft.util.text.ITextComponent;
import net.minecraftforge.api.distmarker.Dist;
import net.minecraftforge.api.distmarker.OnlyIn;

@OnlyIn(Dist.CLIENT)
public class PeasantScreen extends ContainerScreen<Container> {

    private static final ResourceLocation PEASANT_GUI = new ResourceLocation(SiegeMod.MODID, "gui/peasant_gui.png");

    private float mousePosx;
    private float mousePosY;

    private final SiegeEntity peasant;

    public PeasantScreen(Container screenContainer, PlayerInventory inv, ITextComponent titleIn) {
        super((PeasantContainer) screenContainer, inv, titleIn);
        this.peasant = ((PeasantContainer) screenContainer).getPeasant();
        this.guiLeft = 0;
        this.guiTop = 0;
        this.xSize = 176;
        this.ySize = 166;
    }

    @Override
    protected void drawGuiContainerBackgroundLayer(float partialTicks, int mouseX, int mouseY) {
        RenderSystem.color4f(1.0F, 1.0F, 1.0F, 1.0F);
        this.getMinecraft().getTextureManager().bindTexture(PEASANT_GUI);
        int i = (this.width - this.xSize) / 2;
        int j = (this.height - this.ySize) / 2;
        this.blit(i, j, 0, 0, this.xSize, this.ySize);
        InventoryScreen.drawEntityOnScreen(i + 52, j + 50, 22, (float) (i + 51) - this.mousePosx, (float) (j + 75 - 50) - this.mousePosY, this.peasant);
    }

    @Override
    public void render(int p_render_1_, int p_render_2_, float p_render_3_) {
        this.renderBackground();
        this.mousePosx = (float) p_render_1_;
        this.mousePosY = (float) p_render_2_;
        super.render(p_render_1_, p_render_2_, p_render_3_);
        this.renderHoveredToolTip(p_render_1_, p_render_2_);
    }
}

 

Edited June 19, 2020 by OuiOuiCroissant
Updated with solution

[OuiOuiCroissant]

Update!

I have discovered that I MUST use the required constructor:

Spoiler

public PeasantContainer(int containerId, PlayerInventory playerInv, PacketBuffer containerBuffer) {

However, I need both the Screen and Container classes to identify the entity they belong to.

 

I bet I can pass getEntityID through the PacketBuffer parameter of Container class. Do I make a new PacketBuffer in the createMenu method and give it Unpooled.buffer()?

Spoiler

        @Override
        public Container createMenu(int containerId, PlayerInventory playerInv, PlayerEntity player) {
            return new PeasantContainer(containerId, playerInv, new PacketBuffer(Unpooled.buffer().writeInt(PEASANT.getEntityId())));
        }

When I read it in the Container class it throws an IndexOutOfBoundsException. I will need to read up on how PacketBuffer works. I will update if I figure it out.

Spoiler

    public PeasantContainer(int containerId, PlayerInventory playerInv, PacketBuffer containerBuffer) {
        super(SiegeContainerTypes.PEASANT_CONTAINER.get(), containerId);
        this.peasant = (SiegeEntity) playerInv.player.world.getEntityByID(containerBuffer.readInt());

 

[OuiOuiCroissant]

IContainerFactory doesn't have a PacketBuffer field, it only exists as a parameter in its create() method. Where does an instance of PacketBuffer come from? Or should I create my own static instance in my container factory?

 

Implementing IContainerFactory on my container factory has me implement a create() method:

Spoiler

    @Override
    public Container create(int windowId, PlayerInventory inv, PacketBuffer data) {
        return null;
    }
}

But I cannot make a static instance of my container, right? And create() is not a static method so I can't call it from somewhere else. I have nothing to pass into widowId or playerInv from here either.

Spoiler

package com.siegemod.container;

import com.siegemod.SiegeMod;

import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.inventory.container.ContainerType;
import net.minecraft.network.PacketBuffer;
import net.minecraftforge.common.extensions.IForgeContainerType;
import net.minecraftforge.fml.RegistryObject;
import net.minecraftforge.fml.network.IContainerFactory;
import net.minecraftforge.registries.DeferredRegister;
import net.minecraftforge.registries.ForgeRegistries;

public class SiegeContainerTypes implements IContainerFactory<Container> {

    public static final DeferredRegister<ContainerType<?>> CONTAINER_TYPES = new DeferredRegister<>(ForgeRegistries.CONTAINERS, SiegeMod.MODID);

    public static final RegistryObject<ContainerType<PeasantContainer>> PEASANT_CONTAINER = CONTAINER_TYPES.register(SiegeMod.MODID, () -> {
        return IForgeContainerType.create(PeasantContainer::new);
    });

    @Override
    public Container create(int windowId, PlayerInventory inv, PacketBuffer data) {
        return null;
    }
}

 

[OuiOuiCroissant]

I just meant a static field to pass into NetworkHooks.openGui(ServerPlayerEntity, INamedContainerProvider, Consumer<PacketBuffer>) like so:

Spoiler

public static final PacketBuffer CONTAINER_PACKET = new PacketBuffer(Unpooled.buffer());

 

So far my container factory looks like:

Spoiler

package com.siegemod.util;

import com.siegemod.container.PeasantContainer;

import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.network.PacketBuffer;
import net.minecraftforge.fml.network.IContainerFactory;

public class SiegeContainerFactory implements IContainerFactory<Container> {

    @Override
    public Container create(int windowId, PlayerInventory inv, PacketBuffer data) {
        System.out.println("IContainerFactory#CREATE WAS RUN");
        return new PeasantContainer(windowId, inv, data);
    }
}

And I made a screen factory:

Spoiler

package com.siegemod.util;

import com.siegemod.container.PeasantScreen;

import net.minecraft.client.gui.ScreenManager.IScreenFactory;
import net.minecraft.client.gui.screen.inventory.ContainerScreen;
import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.util.text.ITextComponent;

public class SiegeScreenFactory implements IScreenFactory<Container, ContainerScreen<Container>> {

    @Override
    public ContainerScreen<Container> create(Container container, PlayerInventory inv, ITextComponent ITextComponent) {
        System.out.println("ScreenFactory#CREATE WAS RUN");
        return new PeasantScreen(container, inv, ITextComponent);
    }
}

Will both of these create() methods be run if I run NetworkHooks.openGui(ServerPlayerEntity, INamedContainerProvider, Consumer<PacketBuffer>) on the server side?

 

Thank you so much for your patience and help.

[OuiOuiCroissant]

Something I implement? As in I implement an interface? Or do you mean I create a new instance of PacketBuffer like so:

ContainerProvider:

Spoiler

    public class SiegeContainerProvider implements INamedContainerProvider {

        private final SiegeEntity peasant;

        public SiegeContainerProvider(SiegeEntity peasantIn) {
            this.peasant = peasantIn;
        }

        @Override
        public Container createMenu(int containerId, PlayerInventory playerInv, PlayerEntity player) {
            PacketBuffer containerPacket = new PacketBuffer(Unpooled.buffer());
            containerPacket.writeInt(peasant.getEntityId());
            return new PeasantContainer(containerId, playerInv, containerPacket);
        }

        @Override
        public ITextComponent getDisplayName() {
            return peasant.getDisplayName();
        }
    }

Here are my other classes as they currently are:

EntityClass:

Spoiler

package com.siegemod.entities;

import java.util.UUID;

import com.siegemod.container.PeasantContainer;
import com.siegemod.container.PeasantInventory;

import io.netty.buffer.Unpooled;
import net.minecraft.entity.AgeableEntity;
import net.minecraft.entity.Entity;
import net.minecraft.entity.EntityType;
import net.minecraft.entity.ILivingEntityData;
import net.minecraft.entity.SharedMonsterAttributes;
import net.minecraft.entity.SpawnReason;
import net.minecraft.entity.ai.goal.HurtByTargetGoal;
import net.minecraft.entity.ai.goal.LookAtGoal;
import net.minecraft.entity.ai.goal.LookRandomlyGoal;
import net.minecraft.entity.ai.goal.MoveThroughVillageGoal;
import net.minecraft.entity.ai.goal.MoveTowardsTargetGoal;
import net.minecraft.entity.ai.goal.MoveTowardsVillageGoal;
import net.minecraft.entity.ai.goal.SwimGoal;
import net.minecraft.entity.merchant.villager.AbstractVillagerEntity;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.entity.player.ServerPlayerEntity;
import net.minecraft.inventory.Inventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.inventory.container.INamedContainerProvider;
import net.minecraft.item.ItemStack;
import net.minecraft.item.MerchantOffer;
import net.minecraft.nbt.CompoundNBT;
import net.minecraft.nbt.ListNBT;
import net.minecraft.network.PacketBuffer;
import net.minecraft.pathfinding.GroundPathNavigator;
import net.minecraft.util.Hand;
import net.minecraft.util.math.BlockPos;
import net.minecraft.util.text.ITextComponent;
import net.minecraft.world.DifficultyInstance;
import net.minecraft.world.IWorld;
import net.minecraft.world.World;
import net.minecraftforge.fml.network.NetworkHooks;

public abstract class SiegeEntity extends AbstractVillagerEntity {

    protected final double walkSpeed = 0.4D;
    // Convert to ItemHandler
    private final PeasantInventory peasantInventory;
    private final SiegeContainerProvider containerProvider;

    // 0 = wander, 1 = follow, 2 = locked follow, 3 = guard, 4 = locked guard.
    protected double stance = 0;
    // The main controller of this peasant
    protected UUID kingUniqueID;
    // Allowed to control this peasant and access inventory
    protected UUID[] royalFamily;
    // Will not attack/be attacked by the soldiers of people on this list
    protected UUID[] allies;

    protected BlockPos destination;
    protected ItemStack targetItem;

    public SiegeEntity(EntityType<? extends AbstractVillagerEntity> entityType, World worldIn, PlayerEntity kingIn) {
        super(entityType, worldIn);
        this.peasantInventory = new PeasantInventory(new Inventory(16), this);
        this.containerProvider = new SiegeContainerProvider(this);
        if (kingIn != null)
            this.kingUniqueID = kingIn.getUniqueID();

        ((GroundPathNavigator) this.getNavigator()).setBreakDoors(true);
        this.getNavigator().setCanSwim(true);
        this.setCanPickUpLoot(true);
    }

    @Override
    public ILivingEntityData onInitialSpawn(IWorld worldIn, DifficultyInstance difficultyIn, SpawnReason reason, ILivingEntityData spawnDataIn, CompoundNBT dataTag) {
        if (!world.isRemote && reason == SpawnReason.COMMAND)
            this.setKing(world.getClosestPlayer(this, 999).getUniqueID());
        if (this.rand.nextInt(10) == 0)
            this.setLeftHanded(true);
        return super.onInitialSpawn(worldIn, difficultyIn, reason, spawnDataIn, dataTag);
    }

    @Override
    protected void registerGoals() {
        super.registerGoals();
        this.goalSelector.addGoal(0, new SwimGoal(this));
        // We're going to need a custom avoid entity goal
        // We're going to need a custom choose target goal 
        // We're going to need a custom "wander near player bed while unclaimed but eventually wander away and despawn" goal
        this.goalSelector.addGoal(2, new MoveTowardsTargetGoal(this, this.walkSpeed, 32.0F));
        this.goalSelector.addGoal(2, new MoveTowardsVillageGoal(this, this.walkSpeed));
        this.goalSelector.addGoal(3, new MoveThroughVillageGoal(this, this.walkSpeed, false, 4, () -> {
            return false;
        }));
        this.goalSelector.addGoal(7, new LookAtGoal(this, PlayerEntity.class, 6.0F));
        this.goalSelector.addGoal(8, new LookRandomlyGoal(this));

        this.targetSelector.addGoal(2, new HurtByTargetGoal(this));
    }

    @Override
    protected void registerAttributes() {
        super.registerAttributes();
        this.getAttribute(SharedMonsterAttributes.MAX_HEALTH).setBaseValue(20.0D);
        this.getAttribute(SharedMonsterAttributes.FOLLOW_RANGE).setBaseValue(64.0D);
        this.getAttribute(SharedMonsterAttributes.MOVEMENT_SPEED).setBaseValue(this.walkSpeed);

        this.getAttributes().registerAttribute(SharedMonsterAttributes.ATTACK_DAMAGE).setBaseValue(1.0D);

        this.getAttribute(SharedMonsterAttributes.ARMOR).setBaseValue(0.0D);
        this.getAttribute(SharedMonsterAttributes.ARMOR_TOUGHNESS).setBaseValue(0.0D);
        this.getAttribute(SharedMonsterAttributes.KNOCKBACK_RESISTANCE).setBaseValue(10.0F);
    }

    @Override
    public boolean attackEntityAsMob(Entity entityIn) {
        this.swingArm(getActiveHand());
        return super.attackEntityAsMob(entityIn);
    }

    public void livingTick() {
        this.updateArmSwingProgress();
        super.livingTick();
    }

    public void writeAdditional(CompoundNBT compound) {
        super.writeAdditional(compound);
        ListNBT listnbt = new ListNBT();
        for (int i = 0; i < this.peasantInventory.getSlots(); ++i) {
            ItemStack itemstack = this.peasantInventory.getStackInSlot(i);
            if (!itemstack.isEmpty()) {
                listnbt.add(itemstack.write(new CompoundNBT()));
            }
        }
        compound.put("PeasantInventory", listnbt);

        if (this.kingUniqueID != null)
            compound.putUniqueId("KingId", this.kingUniqueID);
    }

    public void readAdditional(CompoundNBT compound) {
        super.readAdditional(compound);

        ListNBT listnbt = compound.getList("PeasantInventory", 10);
        for (int i = 0; i < listnbt.size(); ++i) {
            ItemStack itemstack = ItemStack.read(listnbt.getCompound(i));
            if (!itemstack.isEmpty()) {
                this.peasantInventory.insertItem(i, itemstack, false);
            }
        }

        if (this.kingUniqueID == null && compound.hasUniqueId("KingId")) {
            this.setKing(compound.getUniqueId("KingId"));
        }
    }

    public PlayerEntity getKing() {
        return world.getPlayerByUuid(this.kingUniqueID);
    }

    public void setKing(UUID playerUUIDIn) {
        this.kingUniqueID = playerUUIDIn;
    }

    @Override
    public final boolean processInteract(PlayerEntity player, Hand hand) {
        if (hand == Hand.MAIN_HAND && !world.isRemote) {
            if (player.getUniqueID() == this.kingUniqueID && player instanceof ServerPlayerEntity && !world.isRemote) {
                NetworkHooks.openGui((ServerPlayerEntity) player, this.containerProvider);
                return true;
            }
        }
        return super.processInteract(player, hand);
    }

    public PeasantInventory getPeasantInventory() {
        return peasantInventory;
    }
    /*
    public DyeColor getPrimaryColor() {
        return DyeColor.byId(this.dataManager.get(COLLAR_COLOR));
    }
    
    public void setSecondaryColor(DyeColor collarcolor) {
        this.dataManager.set(COLLAR_COLOR, collarcolor.getId());
    }*/

    @Override
    public AgeableEntity createChild(AgeableEntity ageable) {
        return null;
    }

    @Override
    protected void onVillagerTrade(MerchantOffer offer) {
    }

    @Override
    protected void populateTradeData() {
    }

}

Container Factory:

Spoiler

package com.siegemod.util;

import com.siegemod.container.PeasantContainer;

import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.network.PacketBuffer;
import net.minecraftforge.fml.network.IContainerFactory;

public class SiegeContainerFactory implements IContainerFactory<Container> {

    @Override
    public Container create(int windowId, PlayerInventory inv, PacketBuffer data) {
        return new PeasantContainer(windowId, inv, data);
    }
}

Screen Factory:

Spoiler

package com.siegemod.util;

import com.siegemod.container.PeasantScreen;

import net.minecraft.client.gui.ScreenManager.IScreenFactory;
import net.minecraft.client.gui.screen.inventory.ContainerScreen;
import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.util.text.ITextComponent;

public class SiegeScreenFactory implements IScreenFactory<Container, ContainerScreen<Container>> {

    @Override
    public ContainerScreen<Container> create(Container container, PlayerInventory inv, ITextComponent ITextComponent) {
        return new PeasantScreen(container, inv, ITextComponent);
    }
}

Container:

Spoiler

package com.siegemod.container;

import com.mojang.datafixers.util.Pair;
import com.siegemod.entities.SiegeEntity;

import net.minecraft.enchantment.EnchantmentHelper;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.entity.player.PlayerInventory;
import net.minecraft.inventory.EquipmentSlotType;
import net.minecraft.inventory.IInventory;
import net.minecraft.inventory.container.Container;
import net.minecraft.inventory.container.PlayerContainer;
import net.minecraft.inventory.container.Slot;
import net.minecraft.item.ItemStack;
import net.minecraft.network.PacketBuffer;
import net.minecraft.util.ResourceLocation;
import net.minecraftforge.api.distmarker.Dist;
import net.minecraftforge.api.distmarker.OnlyIn;

public class PeasantContainer extends Container {

    public SiegeEntity peasant;
    public IInventory peasantInventory;

    public static final EquipmentSlotType[] VALID_EQUIPMENT_SLOTS = new EquipmentSlotType[] { EquipmentSlotType.HEAD, EquipmentSlotType.CHEST, EquipmentSlotType.LEGS, EquipmentSlotType.FEET };
    private static final ResourceLocation[] ARMOR_SLOT_TEXTURES = new ResourceLocation[] { PlayerContainer.EMPTY_ARMOR_SLOT_BOOTS, PlayerContainer.EMPTY_ARMOR_SLOT_LEGGINGS,
            PlayerContainer.EMPTY_ARMOR_SLOT_CHESTPLATE, PlayerContainer.EMPTY_ARMOR_SLOT_HELMET };

    public PeasantContainer(int containerId, PlayerInventory playerInv, PacketBuffer containerBuffer) {
        super(SiegeContainerTypes.PEASANT_CONTAINER.get(), containerId);
        this.peasant = (SiegeEntity) playerInv.player.world.getEntityByID(containerBuffer.readInt());
        this.peasantInventory = peasant.getPeasantInventory().getInv();
        this.peasantInventory.openInventory(playerInv.player);

        // MainHand 0
        this.addSlot(new Slot(this.peasantInventory, 0, 32, 62) {

            @Override
            public void onSlotChanged() {
                super.onSlotChanged();
                peasant.getPeasantInventory().markDirty();
            }
        });

        //Armor 1-4
        for (int row = 0; row < 4; row++) {
            final EquipmentSlotType equipmentslottype = VALID_EQUIPMENT_SLOTS[row];
            this.addSlot(new Slot(this.peasantInventory, row + 1, 8, 8 + row * 18) {

                @Override
                public void onSlotChanged() {
                    super.onSlotChanged();
                    peasant.getPeasantInventory().markDirty();
                }

                @Override
                public int getSlotStackLimit() {
                    return 1;
                }

                @Override
                public boolean isItemValid(ItemStack stack) {
                    return stack.canEquip(equipmentslottype, peasant);
                }

                @Override
                public boolean canTakeStack(PlayerEntity playerIn) {
                    ItemStack itemstack = this.getStack();
                    return !itemstack.isEmpty() && !playerIn.isCreative() && EnchantmentHelper.hasBindingCurse(itemstack) ? false : super.canTakeStack(playerIn);
                }

                @OnlyIn(Dist.CLIENT)
                public Pair<ResourceLocation, ResourceLocation> func_225517_c_() {
                    return Pair.of(PlayerContainer.LOCATION_BLOCKS_TEXTURE, ARMOR_SLOT_TEXTURES[equipmentslottype.getIndex()]);
                }
            });
        }

        // OffHand 5
        this.addSlot(new Slot(this.peasantInventory, 5, 56, 62) {

            @Override
            public void onSlotChanged() {
                super.onSlotChanged();
                peasant.getPeasantInventory().markDirty();
            }

            @OnlyIn(Dist.CLIENT)
            public Pair<ResourceLocation, ResourceLocation> func_225517_c_() {
                return Pair.of(PlayerContainer.LOCATION_BLOCKS_TEXTURE, PlayerContainer.EMPTY_ARMOR_SLOT_SHIELD);
            }
        });

        // Main Inventory 6-15
        final int invXPos = 80;
        final int invYPos = 8;
        final int height = 2;
        final int length = 5;
        for (int row = 0; row < height; row++)
            for (int column = 0; column < length; column++)
                this.addSlot(new Slot(this.peasantInventory, (row * length) + column + 6, invXPos + column * 18, invYPos + row * 18));

        // Player Main Inventory
        for (int row = 0; row < 3; ++row)
            for (int column = 0; column < 9; ++column)
                this.addSlot(new Slot(playerInv, column + row * 9 + 9, 8 + column * 18, 102 + row * 18 + -18));

        // Player Hotbar
        for (int row = 0; row < 9; ++row) {
            this.addSlot(new Slot(playerInv, row, 8 + row * 18, 142));
        }
    }

    @Override
    public boolean canInteractWith(PlayerEntity playerIn) {
        return peasant != null && ((playerIn == peasant.getKing() && playerIn.getDistance(peasant) <= PlayerEntity.REACH_DISTANCE.getDefaultValue() + 1) || playerIn.isCreative());
    }

    @Override
    public ItemStack transferStackInSlot(PlayerEntity playerIn, int index) {
        ItemStack itemstack = ItemStack.EMPTY;
        Slot slot = this.inventorySlots.get(index);
        if (slot != null && slot.getHasStack()) {
            ItemStack itemstack1 = slot.getStack();
            itemstack = itemstack1.copy();
            if (index < this.peasantInventory.getSizeInventory()) {
                if (!this.mergeItemStack(itemstack1, this.peasantInventory.getSizeInventory(), this.inventorySlots.size(), true)) {
                    return ItemStack.EMPTY;
                }
            } else if (!this.mergeItemStack(itemstack1, 1, this.peasantInventory.getSizeInventory(), false)) {
                return ItemStack.EMPTY;
            }
            if (itemstack1.isEmpty()) {
                slot.putStack(ItemStack.EMPTY);
            } else {
                slot.onSlotChanged();
            }
        }
        return itemstack;
    }

    public SiegeEntity getPeasant() {
        return this.peasant;
    }
}

[OuiOuiCroissant]

Like so?

Spoiler

    @Override
    public final boolean processInteract(PlayerEntity player, Hand hand) {
        if (hand == Hand.MAIN_HAND && player instanceof ServerPlayerEntity && !world.isRemote) {
            if (this.hasKing() && this.isKing(player)) {
                SiegeEntity peasant = this;
                NetworkHooks.openGui((ServerPlayerEntity) player, this.containerProvider, new Consumer<PacketBuffer>() {
                    @Override
                    public void accept(PacketBuffer buffer) {
                        buffer.writeInt(peasant.getEntityId());
                    }
                });
                return true;
            } else if (!this.hasKing()) {
                return super.processInteract(player, hand);
            }
        }
        return super.processInteract(player, hand);
    }

[OuiOuiCroissant]

My god, it works. Thank you, you absolute legend. Updated post with solution.