wave6-is-component-enabled-check

IsComponentEnabled — Main-Thread Enabled State Check

Intent

Check the current enabled state of an IEnableableComponent on a specific entity using EntityManager.IsComponentEnabled() for imperative main-thread branching.

Use When

• Main-thread gameplay logic must branch on whether a component is enabled
• Conditional logic reads enabled state before deciding to enable or disable
• Single-entity check before an imperative sequence of SetComponentEnabled calls

Avoid When

• Inside a parallel job — use EnabledRefRO in IJobEntity.Execute() instead
• Checking every entity in a query — use query filters (WithAll, WithDisabled) instead; much more efficient

Senior Pattern

// Carry pickup/drop logic on main thread:
if (state.EntityManager.IsComponentEnabled<Carry>(playerEntity))
{
    // Player is currently carrying something — drop it
    var carry = state.EntityManager.GetComponentData<Carry>(playerEntity);
    state.EntityManager.SetComponentEnabled<Carry>(carry.Target, false);
    state.EntityManager.SetComponentEnabled<Carry>(playerEntity, false);
}
else
{
    // Find nearest available ball (Carry present but disabled):
    foreach (var (transform, entity) in
        SystemAPI.Query<RefRO<LocalTransform>>()
                 .WithDisabled<Carry>()
                 .WithEntityAccess())
    {
        if (IsNearest(transform.ValueRO.Position))
        {
            state.EntityManager.SetComponentEnabled<Carry>(entity, true);
            break;
        }
    }
}

// In-job form (read-only):
public void Execute(EnabledRefRO<Carry> carryEnabled, ref PickupDecision decision)
{
    decision.ShouldAttempt = !carryEnabled.ValueRO;
}

Anti-Patterns

• Confusing HasComponent<T>(entity) with IsComponentEnabled<T>(entity) — HasComponent returns true even when the component is disabled; IsComponentEnabled returns the actual bit.
• Calling on an entity that does not have the component at all — exception; use HasComponent<T> guard if structural presence is uncertain.
• Using IsComponentEnabled in hot per-entity loops — use query filters (WithAll/WithDisabled) for bulk cases; O(1) per entity but unnecessary when query-level filtering can replace it.
• Calling IsComponentEnabled without completing state.Dependency — jobs may still be writing the enabled bit; safety error.