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[1.8] Slabs


localtoast9001
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I spent some time getting slabs to work in 1.8 with FML. I wanted to share what I learned with the community. The code is part of the morematerials mod I'm working on and is available here https://github.com/localtoast9001/forge-mods. Pull branch 1.8.

 

How Slabs work in the game:

When a slab is placed in the world, it will place a slab block that takes up half the block, either the bottom or top depending on where it's placed. These are 2 variants of the same block type. When a slab is placed on another slab, it forms a double slab, which is a different block type. When either the slab or the double slab is broken, it drops 1 or 2 items for a half height slab.

 

Classes You'll Need

 

A Common Block Slab Class - This is an abstract class derived from net.minecraft.block.BlockSlab that will handle any variants, block state, and item drops. Example:

/**
* A slab or double slab of stained bricks of a certain color.
*
*/
public abstract class BlockStainedBrickSlab extends BlockSlab

 

A half-height class. - This class is derived from the common block slab class with its only job is to override isDouble() and return false. Unfortunately, isDouble() is called from the BlockSlab constructor itself, so we can't use a flag that gets passed into the constructor.

Example:

/**
* Regular slab of stained bricks.
*
*/
public class BlockHalfStainedBrickSlab extends BlockStainedBrickSlab {
    /**
     * Gets whether or not this is double height.
     * @return always false.
     */
    @Override
    public final boolean isDouble() {
        return false;
    }

 

A double-height slab class - This class is also derived from the common block slab class, except for it returns true from isDouble(). Calling slabs half and double is the convention in the Minecraft code, even though it should be half (0.5) and full (1.0) or full (0.5) and double (1.0).

Example:

/**
* Double slab of stained bricks.
*
*/
public class BlockDoubleStainedBrickSlab extends BlockStainedBrickSlab {
    /**
     * Gets whether or not this is a double stacked slab.
     * @return always true.
     */
    @Override
    public final boolean isDouble() {
        return true;
    }

A Wrapper class for ItemSlab - This class only is needed to get GameRegistry.registerBlock() to call the right constructor with reflection. The arguments to the constructor have to match the types that get passed in through registerBlock() exactly, i.e. they can't refer to the base class.

Example:

/**
* Wrapper around ItemSlab to allow init from GameRegistry.
*
*/
public class ItemBlockStainedBrickSlab extends ItemSlab {
    /**
     * Initializes a new instance of the ItemBlockStainedBrickSlab class.
     * @param block the block behind the item.
     * @param slab the half height slab.
     * @param doubleSlab the full height slab.
     * @param stacked whether or not the block is the stacked version.
     */
    public ItemBlockStainedBrickSlab(
        final Block block,
        final BlockHalfStainedBrickSlab slab,
        final BlockDoubleStainedBrickSlab doubleSlab,
        final Boolean stacked) {
        super(block, slab, doubleSlab);
    }
}

 

Handling Variants and BlockState on the common block slab class

Deriving from BlockSlab requires your common block slab class to participate in handling block state and manage variants. It is important to note that block state needs to translate to metadata which is only 4 bits - 1 bit for top or bottom, so you can only do 8 varieties. So for doing colored slabs (16 varieties), you need multiple registered instances of your block classes. The slab uses the top bit to indicate if the slab is on the bottom or the top. ItemSlab also requires your BlockSlab to give it a variants property it can use to translate to item metadata/damage and validate a slab can stack on another slab. Since I wasn't using block metadata, I just defined a boolean property for variants that is always false.

    /**
     * The property used for the variant.
     * Needed for interactions with ItemSlab.
     */
    private static final PropertyBool VARIANT_PROPERTY =
        PropertyBool.create("variant");

 

The block state in the half slab case will have the variants property and a "half" property to indicate if the slab is on top or bottom. The double slab will only have the variants property.

Constructor changes:

        IBlockState blockState = this.blockState.getBaseState();
        blockState = blockState.withProperty(VARIANT_PROPERTY, false);
        if (!this.isDouble()) {
            blockState = blockState.withProperty(HALF, EnumBlockHalf.BOTTOM);
        }

        setDefaultState(blockState);

 

You also need to override getUnlocalizedName(), getVariant(), getVariantProperty(), getStateFromMeta(), getMetaFromState(), damageDropped(), getItemDropped(), getItem(), and createBlockState().

Example/Template (using boolean variant property which is always false):

    /**
     * Gets the unlocalized name based on metadata/damage.
     * @param metadata block metadata.
     * @return the unlocalized name.
     */
    @Override
    public final String getUnlocalizedName(final int metadata) {
        return this.getUnlocalizedName();
    }

    /**
     * Gets the value of the variant property based on the item.
     * @param itemStack item stack.
     * @return the variant value null.
     */
    @Override
    public final Object getVariant(final ItemStack itemStack) {
        return false;
    }

    /**
     * Gets the variant property.
     * @return the variant property null.
     */
    @Override
    public final IProperty getVariantProperty() {
        return VARIANT_PROPERTY;
    }

    /**
     * Gets a block state from metadata.
     * @param meta the metadata or color value.
     * @return a block state with the meta encoded as the variant property.
     */
    @Override
    public final IBlockState getStateFromMeta(final int meta) {
        IBlockState blockState = this.getDefaultState();
        blockState = blockState.withProperty(VARIANT_PROPERTY, false);
        if (!this.isDouble()) {
            EnumBlockHalf value = EnumBlockHalf.BOTTOM;
            if ((meta & HALF_META_BIT) != 0) {
                value = EnumBlockHalf.TOP;
            }

            blockState = blockState.withProperty(HALF, value);
        }

        return blockState;
    }

    /**
     * Gets the metadata value from a block state.
     * @param state the block state.
     * @return the metadata or color value.
     */
    @Override
    public final int getMetaFromState(final IBlockState state) {
        if (this.isDouble()) {
           return 0;
        }

        if ((EnumBlockHalf) state.getValue(HALF) == EnumBlockHalf.TOP) {
            return HALF_META_BIT;
        } else {
            return 0;
        }
    }

    /**
     * Gets the damage for the block's item when dropped.
     * @param state the block's state.
     * @return the metadata or color value.
     */
    @Override
    public final int damageDropped(final IBlockState state) {
        return 0;
    }

    /**
     * Gets the item dropped when the block is broken.
     * @param blockState the block's state.
     * @param random the random number generator
     * @param unused an integer.
     * @return the half slab item.
     */
    @Override
    public final Item getItemDropped(
        final IBlockState blockState,
        final java.util.Random random,
        final int unused) {
        String blockId = this.innerGetId(false);
        return GameUtility.getItemFromBlock(blockId);
    }

    /**
     * Gets the item dropped when the block is broken.
     * @param world the world
     * @param blockPos the block position.
     * @return the item dropped, the half slab.
     */
    @SideOnly(Side.CLIENT)
    @Override
    public final net.minecraft.item.Item getItem(
        final net.minecraft.world.World world,
        final net.minecraft.util.BlockPos blockPos) {
        String blockId = this.innerGetId(false);
        return GameUtility.getItemFromBlock(blockId);
    }

    /**
     * Creates the block state object.
     * @return the block state with properties defined.
     */
    @Override
    protected final BlockState createBlockState() {
        if (this.isDouble()) {
            return new BlockState(this, new IProperty[] {VARIANT_PROPERTY});
        } else {
            return new BlockState(
                this,
                new IProperty[] {VARIANT_PROPERTY, HALF});
        }
    }

References to getId() returns the registered name of the block (either half or double height).

 

Block Registration

Both the half height and double height versions of the slab need to be registered and a matching ItemSlab has to be registered too. This is done with the overload of GameRegistry.registerBlock() that allows constructor arguments to be passes to the block's item class.

Example:

            BlockStainedBrickSlab slab = new BlockHalfStainedBrickSlab(i);
            BlockStainedBrickSlab doubleSlab =
                new BlockDoubleStainedBrickSlab(i);
            GameRegistry.registerBlock(
                slab,
                ItemBlockStainedBrickSlab.class,
                slab.getId(),
                slab,
                doubleSlab,
                false);
            GameRegistry.registerBlock(
                doubleSlab,
                ItemBlockStainedBrickSlab.class,
                doubleSlab.getId(),
                slab,
                doubleSlab,
                true);

In the example, i is the index of a color, i.e. {black, red, green, etc...}

 

Models

You need 2 block state files, one for the half slab, and one for the double slab. In the example, we had an unused variant property in block state, which we need to keep as part of the variant lookup in the block state file:

half slab template:

{
    "variants": {
        "half=bottom,variant=false": { "model": "morematerials:half_slab_stained_bricks_black" },
        "half=top,variant=false": { "model": "morematerials:upper_slab_stained_bricks_black" }
    }
}

double slab template:

{
    "variants": {
        "variant=false": { "model": "morematerials:stained_bricks_block_black" },
        "variant=true":    { "model": "morematerials:stained_bricks_block_black" }
    }
}

 

In this example, I'm reusing a normal brick block for the model for the double slab. However, each half slab needs 2 models, one for top and one for bottom:

bottom:

{
    "parent": "block/half_slab",
    "textures": {
        "bottom": "morematerials:blocks/stainedbricks_black",
        "top": "morematerials:blocks/stainedbricks_black",
        "side": "morematerials:blocks/stainedbricks_black"
    }
}

top:

{
    "parent": "block/upper_slab",
    "textures": {
        "bottom": "morematerials:blocks/stainedbricks_black",
        "top": "morematerials:blocks/stainedbricks_black",
        "side": "morematerials:blocks/stainedbricks_black"
    }
}

You also need an item model for the half slab, but not the double slab. Like any other item for a block, it refers to its parent block:

Example/Template:

{
    "parent": "morematerials:block/half_slab_stained_bricks_black",
    "display": {
        "thirdperson": {
            "rotation": [ 10, -45, 170 ],
            "translation": [ 0, 1.5, -2.75 ],
            "scale": [ 0.375, 0.375, 0.375 ]
        }
    }
}

Other Quirks

Double slabs should not show up in the creative inventory. This is done with the following logic in the constructor of your common block slab class.

        if (!this.isDouble()) {
            setCreativeTab(CreativeTabs.tabBlock);
        }

 

Half slabs should use neighbor lighting to avoid dark spots in the world when placed. This is set in the constructor of your common block slab class.

        this.useNeighborBrightness = !this.isDouble();

 

Like other blocks/items in 1.8, the inventory model has to be registered. There are other posts on how to do this. The current method is basically:

    /**
     * Helper to register an item model for rendering.
     * @param item the item to register.
     * @param id the unique id of the item.
     * @param metadata the item metadata.
     */
    public static void registerInventoryModel(
        final Item item,
        final String id,
        final int metadata) {
        Minecraft.getMinecraft().getRenderItem().getItemModelMesher().register(
                item,
                metadata,
                new ModelResourceLocation(
                    MODID + id,
                    "inventory"));
    }

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  • 3 weeks later...
  • 1 month later...

Can you please expand on the getId() and innerGetId() methods? I also don't understand where you get "GameUtility" or "HALF_META_BIT" from. I am running the latest version of FML for 1.8.1, and all your code is good except for those little issues. I hope to resolve these issues. I also need help in coding stair blocks, if you're willing. I have the model already registered and the textures as well, but it will only face eastwards. Let me know if you need any code posted.

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  • 1 month later...

Can you please expand on the getId() and innerGetId() methods? I also don't understand where you get "GameUtility" or "HALF_META_BIT" from. I am running the latest version of FML for 1.8.1, and all your code is good except for those little issues. I hope to resolve these issues. I also need help in coding stair blocks, if you're willing. I have the model already registered and the textures as well, but it will only face eastwards. Let me know if you need any code posted.

 

Thank you for posting this localtoast9001.  It has been very helpful so far. 

 

Ragarding getID(), it does appear to be missing from the posted common block class.  I believe this is the same as getName, but having seen another mod using it, I have not been able to determine what the function does that they are using since there are two name values (if statement required?).

 

public String getID()

  {

    return func_176552_j() ? "slab_double" : "slab";

  }

 

I believe GamerUtility was the mod name he was using.  On the HALF_META_BIT, I believe that should be a constant as well, but may be wrong.  I have this currently defined in the common block class:

 

private static final int HALF_META_BIT = 8;

 

I do have normal blocks, stairs, walls and pillars working.  If you have a question about stairs, send me a message and I might be able to point you in the right direction.  Any information anyone can share on the points above is appreciated.  Thanks!

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Can you please expand on the getId() and innerGetId() methods? I also don't understand where you get "GameUtility" or "HALF_META_BIT" from. I am running the latest version of FML for 1.8.1, and all your code is good except for those little issues. I hope to resolve these issues. I also need help in coding stair blocks, if you're willing. I have the model already registered and the textures as well, but it will only face eastwards. Let me know if you need any code posted.

 

These are helper classes I did in the Morematerials mod. Source is on github

    public final class GameUtility {

   

        /**

        * Helper to get an item from its block.

        * @param name the id of the block.

        * @return the matching item.

        */

        public static Item getItemFromBlock(final String name) {

            return GameRegistry.findItem("morematerials", name);

        }

 

        /**

        * Prevents an instance of the GameUtility class from

        * being instantiated.

        */

        private GameUtility() {

        }

    }

 

The half bit is the bit mask for the flag used to convert the 'half' property to metadata.

 

    /**

    * The bit in metadata used by the half property.

    */

    private static final int HALF_META_BIT = 8;

 

The innerGetId() is as follows:

 

    /**

    * Gets the ID of the block.

    * @param isDoubleStacked override the isDouble() method.

    * @return the unique block id.

    */

    private String innerGetId(final boolean isDoubleStacked) {

        String result = "";

        if (isDoubleStacked) {

            result = "double_";

        }

 

        return result + ID + '_' + ColorUtility.COLOR_IDS[this.color];

    }

 

 

 

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  • 7 months later...

Thanks for the tutorial, its really helped me understand 1.8. :)

 

Although my question is the index color, what do we do if we don't have or don't want an index color? because when I delete that portion it freaks out and creates a method. But on the other hand, it asking for me to give it a variable, but I don't have a variable to give it.

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  • 1 year later...

I tried to simplify my code by having all of my slabs run from a single class file, and they work, except that they all drop the same slab. Do you know why that is? 

 

half slab class

package com.chocolatemod.blocks;

import net.minecraft.block.Block;
import net.minecraft.block.material.Material;

public class BlockHalfSlab extends Blockslab {
	
    public BlockHalfSlab(Material materialIn, String string) {
    	super(materialIn, string);
		this.setHarvestLevel("pickaxe", 2);
        this.setHardness(2.0F);
        this.setResistance(10.0F);
        this.setStepSound(soundTypePiston);		}
    
    @Override
    public final boolean isDouble() {
        return false;
    }
}

slab class

package com.chocolatemod.blocks;

import com.chocolatemod.main.GameUtility;
import com.chocolatemod.main.MainRegistry;
import com.chocolatemod.init.ChocolateBlocks;
import com.chocolatemod.main.CommonProxy;

import net.minecraft.block.Block;
import net.minecraft.block.BlockSlab;
import net.minecraft.block.material.Material;
import net.minecraft.block.properties.IProperty;
import net.minecraft.block.properties.PropertyBool;
import net.minecraft.block.state.BlockState;
import net.minecraft.block.state.IBlockState;
import net.minecraft.client.Minecraft;
import net.minecraft.client.resources.model.ModelResourceLocation;
import net.minecraft.creativetab.CreativeTabs;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraftforge.fml.relauncher.Side;
import net.minecraftforge.fml.relauncher.SideOnly;


public abstract class Blockslab extends BlockSlab {

	
    private static final int HALF_META_BIT = 8;

    private static String ID;
    
    private static final PropertyBool VARIANT_PROPERTY =
        PropertyBool.create("variant");
    
	public Blockslab(Material materialIn, String string) {
		super(materialIn);
		ID = string;
		// TODO Auto-generated constructor stub
        if (!this.isDouble()) {
            setCreativeTab(MainRegistry.tabChocolateBlocks);
        }
        this.useNeighborBrightness = !this.isDouble();
	
   
    IBlockState blockState = this.blockState.getBaseState();
    blockState = blockState.withProperty(VARIANT_PROPERTY, false);
    if (!this.isDouble()) {
        blockState = blockState.withProperty(HALF, EnumBlockHalf.BOTTOM);
    }

    setDefaultState(blockState);
    
    }
    
    public final String getId() {
        return this.innerGetId(this.isDouble());
    }
    
    @Override
    public final String getUnlocalizedName(final int metadata) {
        return this.getUnlocalizedName();
    }

    
    @Override
    public final Object getVariant(final ItemStack itemStack) {
        return false;
    }

   
    @Override
    public final IProperty getVariantProperty() {
        return VARIANT_PROPERTY;
    }

    
    @Override
    public final IBlockState getStateFromMeta(final int meta) {
        IBlockState blockState = this.getDefaultState();
        blockState = blockState.withProperty(VARIANT_PROPERTY, false);
        if (!this.isDouble()) {
            EnumBlockHalf value = EnumBlockHalf.BOTTOM;
            if ((meta & HALF_META_BIT) != 0) {
                value = EnumBlockHalf.TOP;
            }

            blockState = blockState.withProperty(HALF, value);
        }

        return blockState;
    }

    
    @Override
    public final int getMetaFromState(final IBlockState state) {
        if (this.isDouble()) {
           return 0;
        }

        if ((EnumBlockHalf) state.getValue(HALF) == EnumBlockHalf.TOP) {
            return HALF_META_BIT;
        } else {
            return 0;
        }
    }

    
    @Override
    public final int damageDropped(final IBlockState state) {
        return 0;
    }

    
    @Override
    public final Item getItemDropped(
        final IBlockState blockState,
        final java.util.Random random,
        final int unused) {
        String blockId = this.innerGetId(false);
        return GameUtility.getItemFromBlock(blockId);
    }

    
    @SideOnly(Side.CLIENT)
    @Override
    public final net.minecraft.item.Item getItem(
        final net.minecraft.world.World world,
        final net.minecraft.util.BlockPos blockPos) {
        String blockId = this.innerGetId(false);
        return GameUtility.getItemFromBlock(blockId);
    }

    
    @Override
    protected final BlockState createBlockState() {
        if (this.isDouble()) {
            return new BlockState(this, new IProperty[] {VARIANT_PROPERTY});
        } else {
            return new BlockState(
                this,
                new IProperty[] {VARIANT_PROPERTY, HALF});
        }
    }
    
   
    public static void registerInventoryModel(
        final Item item,
        final String id,
        final int metadata) {
        Minecraft.getMinecraft().getRenderItem().getItemModelMesher().register(
                item,
                metadata,
                new ModelResourceLocation(
                    MainRegistry.MODID + id,
                    "inventory"));
    }
    
    private String innerGetId(final boolean isDoubleStacked) {
        
        return ID;
    }
}

 

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