GameRule-Extensions

GameRule-Extensions

Mods
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GameRule-Extensions

An extension library to allow mod developers to more easily add custom gamerules, with additional datatype support.

Usage (Mod Developers Only)

Adding a new game rule

  1. Add the API jar as a dependency to your project.
  2. Call dev.rndmorris.gameruleexts.api.GameRulesApi.registerGameRule(...) to add a new gamerule for your mod. The api.rules package contains basic implementations for declaring boolean, numerical, and string gamerules.
  3. If necessary, write your own IGameRule implementation.

Reading a game rule

  1. Call dev.rndmorris.gameruleexts.api.GameRulesApi.getGameRules(...).
  2. The returned IGameRules object can be used to retrieve and update gamerules by their name.

Examples

Creating and reading a gamerule

public class CommonProxy {
  // ...
  public void postInit(FMLPostInitializationEvent event) {
    GameRulesApi.registerGameRule(new FloatGameRule("grassCuttingSwordDamage", 90F));
  }
  // ...
}

public class SwordGrassCutting extends ItemSword {
  // ...
  public boolean hitEntity(ItemStack stack, EntityLivingBase target, EntityLivingBase player) {
    final var gameRules = GameRulesApi.getGameRules(player.worldObj);
    target.attackEntityFrom(DamageSource.causePlayerDamage(player).setMagicDamage(), gameRules.getFloat("grassCuttingSwordDamage"));
    return super.hitEntity(stack, target, player);
  }
  // ...
}

Creating a custom gamerule implementation

Here's an example custom gamerule that maps enums to bytes.

import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.stream.Collectors;

import net.minecraft.command.ICommandSender;
import net.minecraft.nbt.NBTTagCompound;

import dev.rndmorris.gameruleexts.api.IGameRule;
import dev.rndmorris.gameruleexts.api.IRuleValue;
import dev.rndmorris.gameruleexts.api.values.EnumValue;

public class ExampleCustomGameRule implements IGameRule {

    public enum ModDifficulty {

        EASY,
        MEDIUM,
        HARD;

        public static ModDifficulty fromByte(int val, ModDifficulty defaultValue) {
            return switch (val) {
                case 0 -> ModDifficulty.EASY;
                case 1 -> ModDifficulty.MEDIUM;
                case 2 -> ModDifficulty.HARD;
                default -> defaultValue;
            };
        }

        public byte toByte() {
            return switch (this) {
                case EASY -> 0;
                case MEDIUM -> 1;
                case HARD -> 2;
            };
        }
    }

    private final String name = "modDifficulty";
    private final ModDifficulty defaultValue;
    private List<String> tabCompletionValues;

    public ExampleCustomGameRule(ModDifficulty defaultValue) {
        this.defaultValue = defaultValue;
    }

    @Override
    public String getName() {
        return name;
    }

    @Override
    public IRuleValue getDefaultValue() {
        return new EnumValue<>(defaultValue, ModDifficulty.class);
    }

    @Override
    public IRuleValue readValueFromNBT(NBTTagCompound tag) {
        if (!tag.hasKey(name)) {
            return getDefaultValue();
        }
        final var value = ModDifficulty.fromByte(tag.getByte(name), defaultValue);
        return new EnumValue<>(value, ModDifficulty.class);
    }

    @Override
    public void writeValueToNBT(NBTTagCompound tag, IRuleValue value) {
        if (value instanceof EnumValue storedVal && storedVal.getValue() instanceof ModDifficulty enumVal) {
            tag.setByte(name, enumVal.toByte());
        }
    }

    @Override
    public Collection<String> tabCompletionValues(ICommandSender commandSender) {
        if (tabCompletionValues == null) {
            tabCompletionValues = Arrays.stream(ModDifficulty.values())
                    .map(ModDifficulty::toString)
                    .collect(Collectors.toList());
        }
        return tabCompletionValues;
    }
}

Credits

  • rndmorris (primary author)
  • The GTNH team, for the project template