Modding:Adding Block Behavior: Difference between revisions

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{{GameVersion|1.19.3}}

Block Behaviors are useful when you want different blocks to act in the same way, as you can attach one or more block behaviors to an arbitrary number of blocks.

You may want to have a look at the existing [[Block Json Properties#p_behaviors|block behaviors]] before implementing your own.

In this tutorial we'll create a new Behavior that we can attach to blocks to make them movable by right clicking them.

A [[Setting up your Development Environment|development workspace]] is required. Additionally you will need the assets (blocktype, texture and lang file). You can either create your one owns or use those pre-made ones: [https://wiki.vintagestory.at/images/2/2f/Moving_-_No_CS_File.zip Moving - No CS File.zip]

So first of all we need to create the behavior itself, which is a class extending BlockBehavior

<syntaxhighlight lang="csharp">

class Moving : BlockBehavior

</syntaxhighlight>

This class provides several methods we can override. When you use Visual Studio you can find a full list of a methods by hovering with the mouse of "BlockBehavior" and pressing "F12".

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The method <code>bool OnBlockInteractStart(IWorldAccessor world, IPlayer byPlayer, BlockSelection blockSel, ref EnumHandling handling)</code> looks to be ideal for our purpose.

What should it do?

# Calculate the new position to move the block to, based on the block face the player is looking at.

# Check if the block can be placed at this new position.

# Place the same type of block at the new position.

# [[Modding:Behavior_Traversal|Skip]] the default logic that would otherwise place whatever item is held at the old position.

<syntaxhighlight lang="c#">

     public override bool OnBlockInteractStart(IWorldAccessor world, IPlayer byPlayer, BlockSelection blockSel, ref EnumHandling handling)

     {

         // Find the target position

         BlockPos pos = blockSel.Position.AddCopy(blockSel.Face.Opposite);

         if (world.BlockAccessor.GetBlock(pos).IsReplacableBy(block))

         {

             world.BlockAccessor.SetBlock(block.BlockId, pos);

         }

         // If we would not set the handling field the player would still be able to place blocks if he has them in hands.

         handling = EnumHandling.PreventDefault;

         return true;

</syntaxhighlight>

In order the register the BlockBehavior we need to create a mod class, override <code>Start(ICoreAPI)</code> and register it with the given name:

<syntaxhighlight lang="c#">

     public class MovingBlocks : ModSystem

     {

public override void Start(ICoreAPI api)

         {

         }

}

</syntaxhighlight>

In order to finish everything, open the modtools and type in <code>pack <your mod id></code>. Now you can take the zip file and share it with other people.

* for VS 1.9: [https://wiki.vintagestory.at/images/2/2a/Moving_v1.0.0.zip Moving_v1.0.0.zip]

* for VS 1.6: [https://wiki.vintagestory.at/images/c/cb/Moving.zip Moving.zip]

<youtube>8eVG0uQF2xs</youtube>

Our behavior is still rather simple, but there are a lot more possibilities. A behavior can have special properties, which can be defined by the blocktype itself.

The behavior liquid supports some special properties as shown in this example of the water blocktype:

<syntaxhighlight lang="json">

behaviors: [

</syntaxhighlight>

In order to take care of special properties there is a method called <code>Initialize(JsonObject)</code>. Each blocktype creates a new instance of the behavior, so the method can be used to parse the properties.

So what kind of properties could we add?

* push distance

* pull block if player is sneaking

First of all, we need to override the method in our block behavior class ...

<syntaxhighlight lang="c#">

         public override void Initialize(JsonObject properties)

</syntaxhighlight>

Additionally we need to add two fields, one for the distance and another one if the player should pull the block while sneaking ...

<syntaxhighlight lang="c#">

         public int distance = 1;

</syntaxhighlight>

Now we can parse the two properties like so:

<syntaxhighlight lang="c#">

         distance = properties["distance"].AsInt(1);

</syntaxhighlight>

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The next thing we need to change is the interact method itself, so that it takes care of the distance and the pull properties ...

<syntaxhighlight lang="c#">

         public override bool OnBlockInteractStart(IWorldAccessor world, IPlayer byPlayer, BlockSelection blockSel, ref EnumHandling handling)

         {

             // Find the target position

             BlockPos pos = blockSel.Position.AddCopy(pull && byPlayer.WorldData.EntityControls.Sneak ? blockSel.Face : blockSel.Face.Opposite, distance);

             // Can we place the block there?

             if (world.BlockAccessor.GetBlock(pos).IsReplacableBy(block))

             {

                 // Remove the block at the current position and place it at the target position

                 world.BlockAccessor.SetBlock(0, blockSel.Position);

                 world.BlockAccessor.SetBlock(block.BlockId, pos);

             }

             // Notify the game engine other block behaviors that we handled the players interaction with the block.

             // If we would not set the handling field the player would still be able to place blocks if he has them in hands.

             handling = EnumHandling.PreventDefault;

             return true;

</syntaxhighlight>

Let's create another block using this behavior, but this time we will configure some additional properties ...

<syntaxhighlight lang="json">

behaviors: [

</syntaxhighlight>

The block will be pushed two blocks instead of one and the player can pull it by sneaking while right clicking.

* for VS 1.9: [https://wiki.vintagestory.at/images/7/7b/Advancedmoving_v1.0.0.zip AdvancedMoving_v1.0.0.zip]

* for VS 1.6: [https://wiki.vintagestory.at/images/7/72/AdvancedMoving.zip AdvancedMoving.zip]

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