Flexweave Documentation

Visit active effects to compute max health, attack speed, and other runtime values.

Effect-backed derived stats follow the same pattern:

Store the base value in an Attribute.
Apply active effects with typed payloads.
In the derived calculator, visit active effects for the target.
Refresh the derived attribute after effect application, removal, or expiration.

effects.visit_target(player, |effect| {
    if let EffectPayload::AttackSpeedBonus { amount } = effect.payload {
        bonus += amount;
    }
});

This keeps effect semantics in the consumer runtime. Flexweave does not need to know that one payload affects attack speed and another affects max health.

The same structure can power multiple derived attributes. The RPG runtime keeps base attack speed stored, then computes effective attack speed from active buffs:

let attack_speed = {
    let base_attack_speed = Rc::clone(&base_attack_speed);
    let effects = Rc::clone(&effects);
    DerivedAttribute::new(move |id| {
        let base = base_attack_speed.borrow().get(id)?;
        let mut bonus = 0.0;
        effects.borrow().visit_target(id, |effect| {
            if let EffectPayload::AttackSpeedBonus { amount } = effect.payload {
                bonus += amount;
            }
        });
        Some(base + bonus)
    })
};

Refresh derived attributes after the runtime changes the inputs they read:

DerivedAttributeRefresh::new(player).run_streaming(&mut attack_speed, |change| {
    derived_events.borrow_mut().push(change);
});

Derived attributes should be pure reads over existing runtime state. That keeps the refresh predictable and makes expiration easy: tick effects, refresh the derived values, then emit or adapt the resulting changes.

Use this with:

Calculate Derived Stats from Effects