Items and blocks

Techniques that hand out items, craft them, fire a transmutation projectile, or turn block hits into something.

ProduceItemAbility

Hands the user an item the fruit makes out of itself: salt, honey, gum, cotton, bone. There is no recipe and no cost, because the user is the material.

public class MySpareBoneAbility extends ProduceItemAbility {

    public MySpareBoneAbility(AbilityCore<MySpareBoneAbility> core) {
        super(core);
        this.cooldown = 10.0F;
    }

    @Override
    protected ItemStack getProducedItem(LivingEntity user) {
        return new ItemStack(Items.BONE);
    }

    @Override
    protected SoundEvent getProduceSound() {
        return SoundEvents.BONE_BLOCK_BREAK;
    }
}

• getProducedItem(user) is called on each use, so the amount can depend on the user. Return ItemStack.EMPTY to produce nothing; the cooldown still runs, so a technique that can fail should tell the player itself.
• A full inventory drops the item at the user's feet instead of deleting it, and a holder without an inventory (a mob using the ability) drops it on the ground.
• getProduceSound() is silent by default. Override getProduceVolume() (default 0.7) and getProducePitch() (default 1.0) to shape it.

Produce, not craft

If your technique has no recipe and no cost, use this class rather than CraftingAbility: the latter would need three methods that return true unconditionally, a charge that never starts, and a "missing materials" message that can never appear.

CraftingAbility

Materials in, item out: the technique checks a recipe, takes its cost, and produces a result.

public class MyForgeAbility extends CraftingAbility {

    public MyForgeAbility(AbilityCore<MyForgeAbility> core) {
        super(core);
        this.cooldown = 40.0F;
        this.chargeable = true;
        this.chargeTime = 60.0F;
    }

    @Override
    protected boolean isCraftable(LivingEntity user) {
        return user instanceof Player player && player.getInventory().countItem(Items.IRON_INGOT) >= 3;
    }

    @Override
    protected boolean consummeMaterials(LivingEntity user) {
        // remove the 3 ingots; return false if that failed
        return true;
    }

    @Override
    protected void craftItem(LivingEntity user) {
        // give the result
    }
}

• isCraftable is checked on the press. When it fails, a player is sent message, which defaults to "You do not have the materials to use this ability." Set it in the constructor to a translatable component of your own to say what is missing.
• With chargeable = true, the ingredients are taken and the item crafted at the end of a chargeTime charge; otherwise on the press.
• The cooldown (cooldown, default 5) only starts when consummeMaterials returned true.

The method is spelled consummeMaterials

With a double m. Override it under that exact name, or the compiler reports an unimplemented abstract method.

TransmutationAbility

Fires a transmutation projectile and holds a pose until the projectile is gone.

public class MyTransmuteAbility extends TransmutationAbility {

    public MyTransmuteAbility(AbilityCore<MyTransmuteAbility> core) {
        super(core);
    }

    @Override
    protected NuProjectileEntity createProjectile(LivingEntity entity) {
        return new MyTransmutationProjectile(entity.level(), entity, this);
    }

    @Override
    protected SoundEvent getShootSound() {
        return MySounds.TRANSMUTE.get();
    }

    @Override
    protected AnimationId<?> getShootAnimation() {
        return AkumaAnimations.RIGHT_ARM_FORWARD;
    }
}

The sound and the pose are asked of the subclass because they belong to the fruit, not to the mechanic. Defaults: a cooldown of 400, a projectile speed of 2.0 and an inaccuracy of 0.5. The library's TransmutationProjectile is the matching projectile base class.

BlockUseAbility

A state in which hitting a block does something: the user activates the technique, then each block they punch triggers onBlockUsed, until a use limit or the end of the state.

public class MyPetrifyAbility extends BlockUseAbility {

    public MyPetrifyAbility(AbilityCore<MyPetrifyAbility> core) {
        super(core);
    }

    @Override
    public boolean onBlockUsed(LivingEntity entity, BlockPos pos, Level world) {
        world.setBlock(pos, Blocks.STONE.defaultBlockState(), 3);
        return true;
    }

    @Override public float getPunchCooldown() { return 100.0F; }
    @Override public Predicate<LivingEntity> canActivate() { return entity -> true; }
    @Override public int getUseLimit() { return 3; }
    @Override public boolean GetAllowBlockActivation() { return false; }
}

Member	Meaning
onBlockUsed(entity, pos, world)	what a punched block does
canActivate()	whether a hit counts; a failing predicate lets the hit through untouched
getUseLimit()	uses before the state ends; 0 or less for no limit
getPunchHoldTime()	how long the state lasts; -1 (default) until pressed again
getPunchCooldown()	cooldown started when the state ends
isActive()	whether the state is running

The ability's statsComponent is applied for the duration of the state, so modifiers added to it in the constructor only count while the technique is active.

Block hits are delivered by the library's BlockTriggerComponent, registered under AkumaAbilityKeys.BLOCK_TRIGGER, which you can also add to an ability of your own to react to block hits.