[1.9.4] Deleting a block in the world, and dropping items where that block was?

[T-10a]

Hello,

I've been making a new item that I'm planning on making to delete log blocks, and replace it with at least 6 plank blocks of that kind of wood. So far, it's got the shovel code (i.e. turn grass into paths) as a placeholder right click event. What could I use to make this item do what I want? Thanks if you can help.

[coolAlias]

#onItemUse gives you the block position / face clicked - check if it's a log, set it to air if it is and drop an ItemStack containing 6 planks. Might be easier to use the crafting recipes to fetch the correct plank for the log given and drop that.

[T-10a]

Ok, how would I drop the item at the block's posistion? I'm not sure which call would spawn an item entity.

[MCrafterzz]

This code will fix it:

worldIn.destroyBlock(new BlockPos(x,y, z), true);

true makes it drop items.

[T-10a]

I added that line into the code, but now it seems to not destroy the block in the world.

Here's my code:

 

package com.t10a.minedran.item.tools;

import com.t10a.minedran.reference.Reference;

import net.minecraft.block.Block;
import net.minecraft.block.material.Material;
import net.minecraft.block.state.IBlockState;
import net.minecraft.creativetab.CreativeTabs;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.init.Blocks;
import net.minecraft.init.SoundEvents;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraft.util.EnumActionResult;
import net.minecraft.util.EnumFacing;
import net.minecraft.util.EnumHand;
import net.minecraft.util.SoundCategory;
import net.minecraft.util.math.BlockPos;
import net.minecraft.world.World;

public class ItemHandsaw extends Item
{
private final Item.ToolMaterial material;

public ItemHandsaw(ToolMaterial material)
{
	this.material = material;
	this.setMaxStackSize(1);
	this.setMaxDamage(material.getMaxUses());
	this.setCreativeTab(CreativeTabs.TOOLS);
	this.setUnlocalizedName(Reference.ItemBase.HANDSAW.getUnlocalizedName() + "_" + getToolMaterialName().toLowerCase());
	this.setRegistryName(Reference.ItemBase.HANDSAW.getRegistryName()  + "_" + getToolMaterialName().toLowerCase());
}

public EnumActionResult onItemUse(ItemStack stack, EntityPlayer playerIn, World worldIn, BlockPos pos, EnumHand hand, EnumFacing facing, float x, float y, float z)
    {
        if (!playerIn.canPlayerEdit(pos.offset(facing), facing, stack))
        {
            return EnumActionResult.FAIL;
        }
        else
        {
            IBlockState iblockstate = worldIn.getBlockState(pos);
            Block block = iblockstate.getBlock();

            if (facing != EnumFacing.DOWN && worldIn.getBlockState(pos.up()).getMaterial() == Material.AIR && block == Blocks.LOG)
            {
            	worldIn.destroyBlock(new BlockPos(x,y,z), true);
                worldIn.playSound(playerIn, pos, SoundEvents.ITEM_SHOVEL_FLATTEN, SoundCategory.BLOCKS, 1.0F, 1.0F);

                if (!worldIn.isRemote)
                {
                    stack.damageItem(1, playerIn);
                }

                return EnumActionResult.SUCCESS;
            }
            else
            {
                return EnumActionResult.PASS;
            }
        }
    }    

public String getToolMaterialName()
    {
        return this.material.toString();
    }
    
    public int getItemEnchantability()
    {
        return this.material.getEnchantability();
    }
    
    public boolean getIsRepairable(ItemStack toRepair, ItemStack repair)
    {
        ItemStack mat = this.material.getRepairItemStack();
        if (mat != null && net.minecraftforge.oredict.OreDictionary.itemMatches(mat, repair, false)) return true;
        return super.getIsRepairable(toRepair, repair);
    }
}

 

[Choonster]

The three

float

arguments of

Item#onItemUse

are where the player clicked on the block. The block's position in the world is given to you as the

BlockPos

argument.

 

Always annotate override methods with

@Override

so you get a compilation error if they don't actually override a super method.

[T-10a]

Okay, it works and it drops the log block. How would I check for the type of log, and drop the corresponding plank blocks in a specific amount?

[Choonster]

Use

World#getBlockState

to get the

IBlockState

at the specified position. Use

IBlockState#getBlock

to get the

Block

represented by the

IBlockState

.

 

If you only want to handle vanilla logs, check if the

Block

is

Blocks.LOG

or

Blocks.LOG2

. If it is, use

IBlockState#getValue

to get the value of the

BlockOldLog.VARIANT

property (if it's

Blocks.LOG

) or the

BlockNewLog.VARIANT

property (if it's

Blocks.LOG2

). This will give you a

BlockPlanks.EnumType

value.

 

You can then create an

ItemStack

of

Blocks.PLANKS

, using the value returned by

BlockPlanks.EnumType#getMetadata

as the metadata. To drop this in the world, use

Block.spawnAsEntity

.

 

Handling modded logs will be a bit trickier because there's no easy and reliable way to know what the corresponding planks are. You can use

Block#isWood

to check if a block is a log.

 

To get the corresponding planks, you can either:

• Assume that a single log in the crafting grid will result in planks (which may or may not be the case): Create an

  InventoryCrafting

  with a dummy

  Container

  , put an

  ItemStack

  of the logs in it and use

  CraftingManager#findMatchingRecipe

  to get the resulting planks

  ItemStack

  .
  

  • Pros: Has the potential to work for any mod without having to explicitly add support. Cons: Not guaranteed to work for all mods.

   

   

   

  [*]Create a class to hold the log to plank conversion recipes (similar to

  FurnaceRecipes

  ), register a recipe for each vanilla log and then use this in

  ItemHandsaw

  . You can then add recipes for other mods' logs as needed.

  • Pros: Guaranteed to work for any mod you've added support for. Cons: Only works for mods you've explicitly added support for.

   

[T-10a]

Ok, I'm interested in creating a log to plank recipe class. How would I get started with that?

[Choonster]

I think the best way to implement this is to have your recipe class store a

Map<Block, Function<IBlockState, ItemStack>>

. You can then have a method that takes an

IBlockState

, looks up the

Function

in the

Map

using the

Block

, calls the

Function

with the

IBlockState

and returns the resulting

ItemStack

. Return

null

if there's no

Function

for the specified

Block

.

 

You can then call this method in

ItemHandsaw#onItemUse

. If it returns a non-

null

value, set the block to air and drop the

ItemStack

in the world.

[T-10a]

Okay, I'm starting to make the class. After trying to emulate the furnace recipe class, I've gotten this so far (I know, it won't work. This is as far as I've gone before I start getting lost in what to change to make it work)

 

package com.t10a.minedran.item.crafting;

import net.minecraft.item.ItemStack;

import com.google.common.collect.Maps;
import java.util.Map;
import java.util.Map.Entry;

import javax.annotation.Nullable;

import com.google.common.base.Function;

import net.minecraft.block.Block;
import net.minecraft.block.properties.IProperty;
import net.minecraft.block.state.IBlockState;
import net.minecraft.init.Blocks;

public class HandsawRecipes
{
private Map<Block, Function<IBlockState, ItemStack>> handsawList = Maps.<Block, Function<IBlockState, ItemStack>>newHashMap();

private HandsawRecipes(Block input, IBlockState iblockstate, Function<IBlockState, ItemStack> planks)
    {
	this.addHandsawRecipe(input, iblockstate, planks);
    }

    public void addHandsawRecipe(Block input, IBlockState iblockstate, Function<IBlockState, ItemStack> planks)
    {
        if (getSmeltingResult(input) != null) { net.minecraftforge.fml.common.FMLLog.info("Ignored handsaw recipe with conflicting input: " + input + " = " + planks); return; }
        this.handsawList.put(input, planks);
    }
    
    @Nullable
    public ItemStack getSmeltingResult(Block input)
    {
        for (Entry<Block, Function<IBlockState, ItemStack>> entry : this.handsawList.entrySet())
        {
            if (this.compareItemStacks(input, (Block)entry.getKey()))
            {
                return (ItemStack)entry.getValue();
            }
        }

        return null;
    }
    
    private boolean compareItemStacks(Block input, Block output)
    {
        return output.getBlockState() == input.getBlockState();
    }
    
    public Map<Block, Function<IBlockState, ItemStack>> getSmeltingList()
    {
        return this.handsawList;
    }
}

 

[Choonster]

The only methods you need in

HandsawRecipes

are the following:

 

• 
  

  void addHandsawRecipe(Block, Function<IBlockState, ItemStack>)

  
  

  • Get the

    Function

    for the

    Block

    from the

    Map

    .
    

  • If it exists, log or throw an error. If it doesn't, add the

    Function

    argument to the

    Map

    .

   

   

   

  [*]

  @Nullable ItemStack geResult(IBlockState)

  • Get the

    IBlockState

    's

    Block

    , then get the

    Function

    for that

    Block

    from the

    Map

    .
    

  • If there's no

    Function

    , return

    null

    . If there is a

    Function

    , call

    Function#apply

    with the

    IBlockState

    and return the resulting

    ItemStack

    .

   

 

If you're going to use a singleton instance like

FurnaceRecipes

does, you'll also need an instance field and a static method to get the instance.

[T-10a]

Okay, I cleaned up the code, and I'm now getting a syntax error of 'Syntax error, insert "... VariableDeclaratorId" to complete FormalParameter' with Block & IBlockState, as well as Eclipse wanting to take out a bunch of brackets.

 

Here's what I've cleaned up and tweaked so far:

 

package com.t10a.minedran.item.crafting;

import java.util.Map;

import javax.annotation.Nullable;

import com.google.common.base.Function;
import com.google.common.collect.Maps;

import net.minecraft.block.Block;
import net.minecraft.block.state.IBlockState;
import net.minecraft.item.ItemStack;
import net.minecraft.item.crafting.FurnaceRecipes;


public class HandsawRecipes
{
private static final HandsawRecipes HANDSAW_RECIPES = new HandsawRecipes();
private Map<Block, Function<IBlockState, ItemStack>> handsawList = Maps.<Block, Function<IBlockState, ItemStack>>newHashMap();

public static HandsawRecipes instance()
    {
        return HANDSAW_RECIPES;
    }

    public HandsawRecipes() 
    {

}
    
    public void addHandsawRecipe(Block, Function<IBlockState, ItemStack>)
    {
    	
    }
    
    @Nullable 
    public ItemStack geResult(IBlockState)
    {
    	for (Entry<ItemStack, ItemStack> entry : this.handsawList.entrySet())
        {
            if (this.compareItemStacks(stack, (ItemStack)entry.getKey()))
            {
                return (ItemStack)entry.getValue();
            }
        }
        return null;
    }
}

 

[Choonster]

The method signatures I posted aren't valid Java themselves, they're using an abbreviated notation without the parameter names.

 

You weren't meant to blindly copy-paste them.

[T-10a]

Sorry about that... I'm not familiar with Functions<> and creating custom recipe handlers.

But I'm learning along the way.