Modding:Block Entity

Introduction

A block entity is a construct that you can tack onto an existing block to give it additional functionality. Whenever a block should do something on a regular interval or store extra information, such as the contents of a chest block, you need a block entity. It's highly recommend to have read the tutorial about Basic Blocks and Block Class in order to understand this tutorial properly.

The Texture Flipper

Let's create a block which switches its texture every 3 seconds. It should have two variants "on" and "off". Additionally we need to define the blockentity class like so:

	entityClass: "tickingcounter",

You can download the assets here and place it in your mods directory.

The BlockEntity

Now we need to register our blockentity class and therefore we need to create a new *.cs file in our project. Let's name it Ticking.cs.

First of all you need to create the blockentity class itself. Therefore you need to extend BlockEntity:

    public class TickingBlockEntity : BlockEntity
    {
    
    }

---

This class needs to have a timer, once the timer reaches 3 seconds it should replace the current block with the different state.

In order to create a timer we need to register a tick listener. Therefore we need to override Initialize(ICoreAPI):

        public override void Initialize(ICoreAPI api)
        {
            base.Initialize(api);
        }

add a counter (which should increase per tick) ...

        public int timer;

... and the actual ticking method ...

        public void onTick(float par)
        {
        
        }

To register the ticking method we can use RegisterGameTickListener in Inizialize

        public override void Initialize(ICoreAPI api)
        {
            base.Initialize(api);
            RegisterGameTickListener(onTick, 20);
        }

The timer itself should increase per tick. It ticks 20 times per seconds, meaning 3 seconds have passed after the timer has reached 60. So if it's greater than 60 it should replace the block:

        public void onTick(float par)
        {
            timer++;
            if(timer > 60)
            {
                Block block = api.World.BlockAccessor.GetBlock(pos);
                if (block.Code.Path.EndsWith("-on"))
                    block = api.World.GetBlock(block.CodeWithParts("off"));
                else
                    block = api.World.GetBlock(block.CodeWithParts("on"));
                api.World.BlockAccessor.SetBlock(block.BlockId, pos);
            }
        }

---

Furthermore we need to save the current time:

        public override void ToTreeAttributes(ITreeAttribute tree)
        {
            base.ToTreeAttributes(tree);
            tree.SetInt("timer", timer);
        }

        public override void FromTreeAtributes(ITreeAttribute tree)
        {
            base.FromTreeAtributes(tree);
            timer = tree.GetInt("timer");
        }

Registering the Block Entity

Registering the blockentity class is rather simple (rather similar to registering a block class). You need a mod class and override Start(ICoreAPI):

    public class Ticking : ModBase
    {

        public override void Start(ICoreAPI api)
        {
            base.Start(api);
            api.RegisterBlockEntity("tickingcounter", typeof(TickingBlockEntity));
        }

    }

Testing

Now everything is ready to run the first test:

Distribution

There is only one thing left to do and that is to place your *.cs file in the zip archive. Once that is done you can share it with other people. It will work in the same way as ordinary mods, you can install it by copying it into the mods folder.

Here is my version: Ticking.zip