Morph gates and stats

Two small classes for Zoan fruits, and any fruit with a morph: MorphGates locks a technique to a form, and MorphStats declares a form's attributes.

Locking a technique to a form: MorphGates

A technique that only makes sense in one form needs a use condition. MorphGates.requiring builds it as a constant, next to the morphs it names:

MyGates.java

public class MyGates {

    public static final Ability.ICanUseEvent WALK_POINT =
            MorphGates.requiring(MyMorphs.WALK_POINT);

    public static final Ability.ICanUseEvent EITHER_POINT =
            MorphGates.requiring(MyMorphs.HEAVY_POINT, MyMorphs.WALK_POINT);
}

Then, in the ability's constructor:

this.addCanUseCheck(MyGates.WALK_POINT);
this.addContinueUseCheck(MyGates.WALK_POINT);

The gate passes while the user is in any one of the morphs given. Pass the registry objects themselves: RegistryObject is a Supplier, and the morphs are only resolved when the check runs.

Add the gate on continue as well as on use

addCanUseCheck only gates the key press. addContinueUseCheck is what ends a held, charged or continuous technique when the user drops out of the form mid-use. Without it, a player who leaves the form keeps holding a grab or keeps a bonus that belongs to a body they no longer have.

Gates compose

Ability.ICanUseEvent carries the base mod's and, or and not, so a gate combines with any other condition:

this.addCanUseCheck(MyGates.WALK_POINT.and(MyHelper::requiresDaylight));

requiring() with no morph, or with a null one, throws immediately. An empty gate would otherwise only surface as an ability nobody can use.

Declaring a form's attributes: MorphStats

A morph ability's stats used to take three declarations per attribute: a field, a line wiring it into the ChangeStatsComponent, and the modifier itself. MorphStats knows the UUID, attribute and default operation of each stat, so only the number is left:

MyWalkPointAbility.java

public MyWalkPointAbility(AbilityCore<MyWalkPointAbility> core) {
    super(core);
    MorphStats.on(this.statsComponent, INSTANCE, "My Walk Point")
            .movementSpeed(0.55)
            .punch(4.0)
            .armor(3.0)
            .jump(1.8)
            .fallResistance(2.5);
}

Call it from the constructor. Each method applies its modifier immediately, so there is no final call to forget.

Available stats

health, movementSpeed, armor, armorToughness, punch, attackSpeed, blockReach, entityReach, stepHeight, knockbackResistance, fallResistance, toughness, jump, regenRate, swimSpeed, miningSpeed, friction, gravity, and custom(...) for any other attribute, including one from your own registry.

Operations

Each stat has a default operation, chosen from how existing forms use it:

Stat	Default operation
health	MULTIPLY_TOTAL
movementSpeed	MULTIPLY_BASE
every other stat	ADDITION

Every stat also has a two-argument form taking the operation explicitly:

.movementSpeed(0.3, Operation.MULTIPLY_TOTAL)

Check the operation when migrating an existing form

The defaults match the common case, not every case. Several stats are used with more than one operation across existing addons. When you move a hand-written stat block to MorphStats, compare the operation as well as the number: a silently changed operation is a balance change.

Stats that only apply some of the time

onlyWhile makes every stat set after it conditional:

MorphStats.on(this.statsComponent, INSTANCE, "My Heavy Point")
        .armor(3.0)                       // always
        .onlyWhile(this::isDigging)
        .movementSpeed(1.5)               // only while digging
        .jump(3.0);                       // only while digging

Pass null to go back to unconditional stats.

One modifier per attribute

A ChangeStatsComponent holds a single modifier per attribute. Two techniques that want different bonuses on the same attribute at the same time need separate components or separate forms, not two movementSpeed calls.