Using Forge version 1.11-13.19.1.2195. I've set up a block, tile entity, container and GUI, and I want the container's slots to appear/disappear when a certain item is placed in one of the slots. I have tried setting each slot's xPosition, however the container's slots are only redrawn when the container is closed and re-opened. Is there a way to change the positions of the slots whilst the GUI for the block is still open?

Ahh, makes sense. How can I do that?

Sorry if I'm missing something really obvious here, but after the container has been opened, using addSlotToContainer() or slot.xDisplayPosition doesn't move the slots in my container.

This is my container class. As far as I understand detectAndSendChanges() runs every tick, so that means as soon as the GUI is opened, slot 4 should be moved to position (0,0), and slot 3 should be moved to position (10,10). But this doesn't happen.

 

package kemm.common.container;

import kemm.Util;
import kemm.common.block.SingleSlotBlock;
import kemm.common.item.modules.Module;
import kemm.common.item.modules.Module.EnumPosition;
import kemm.common.tileentity.SingleSlot;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.inventory.Container;
import net.minecraft.inventory.IInventory;
import net.minecraft.inventory.Slot;
import net.minecraft.item.ItemStack;
import net.minecraft.tileentity.TileEntity;
import net.minecraft.util.math.BlockPos;
import net.minecraft.world.World;
import net.minecraftforge.items.CapabilityItemHandler;
import net.minecraftforge.items.IItemHandler;
import net.minecraftforge.items.SlotItemHandler;

public class ContainerBlock extends Container {

private SingleSlot te;
private World blockWorld;
private BlockPos position;
private IInventory plInv;

public ContainerBlock(IInventory playerInv, SingleSlot tile_entity, World worldIn, BlockPos pos) {
	this.te = tile_entity;
	this.blockWorld = worldIn;
	this.position = pos;
	this.plInv = playerInv;
	addBlockSlots();
	addPlayerSlots(playerInv);
	System.out.println("Drawing container");
}

private void addPlayerSlots(IInventory playerInv) {
	//Inventory
	for (int row = 0; row < 3; row++) {
		for (int col = 0; col < 9; col++) {
			int x = 48 + col * 18;
			int y = 171 + row * 18;
			this.addSlotToContainer(new Slot(playerInv, col + row * 9 + 9, x, y));
		}
	}
	//Hotbar
	for (int col = 0; col < 9; col++) {
		int x = 48 + col * 18;
		int y = 229;
		this.addSlotToContainer(new Slot(playerInv, col, x, y));
	}
}

private void addBlockSlots() {

	IItemHandler handler = this.te.getCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY, null);
	//Draw module-input slots
	for (int col = 0; col < 2; col++ ) {
		for(int row = 0; row < 3; row++) {
			int slotNo = row + col*3;
			int x = col * 90 + 75;
			int y = row * 18 + 62;

			if (slotNo < SingleSlotBlock.size) {
				addSlotToContainer(new SlotModule(handler, this, slotNo, x, y));
			}
		}

	}		
}


@Override
public ItemStack transferStackInSlot(EntityPlayer playerIn, int index) {
	return null;
}

@Override
public boolean canInteractWith(EntityPlayer playerIn) {
	return te.canInteractWith(playerIn);
}


@Override
public void detectAndSendChanges() {
	setSlotPosition(this.getSlot(4), 0, 0);
	setSlotPosition(this.getSlot(3), 10, 10);
	super.detectAndSendChanges();
}



public void setSlotPosition(Slot slot, int xPos, int yPos) {
	slot.xDisplayPosition = xPos;
	slot.yDisplayPosition = yPos;
}

}

Sorry, I was being stupid. Needed to change the positions in the container class and the GUI class (e.g. Client and Server so exactly what you said), thanks for your help