wave6-entity-manager-set-component-enabled

EntityManager.SetComponentEnabled — Immediate Main-Thread Toggle

Intent

Immediately enable or disable an IEnableableComponent on one entity or all entities matching a query using EntityManager.SetComponentEnabled or SystemAPI.SetComponentEnabled on the main thread.

Use When

• Immediate state change needed on main thread (no deferred overhead, no one-frame delay)
• Batch enable/disable of all entities matching a query in a single call
• Imperative gameplay logic that must branch and change enabled state in the same frame

Avoid When

• Inside a parallel job — use ECB.SetComponentEnabled or EnabledRefRW
• Inside a foreach iterating the same entities — invalidates query iterator mid-iteration; use ECB to defer

Senior Pattern

// Single entity (immediate):
SystemAPI.SetComponentEnabled<ActiveBehavior>(entity, true);

// Batch query (all entities matching query, immediate — O(chunks) not O(entities)):
EntityQuery spinQuery = SystemAPI.QueryBuilder().WithAll<Spin>().Build();
state.EntityManager.SetComponentEnabled<Spin>(spinQuery, false);

// Conditional branch using IsComponentEnabled (not HasComponent):
if (state.EntityManager.IsComponentEnabled<Carry>(playerEntity))
{
    // drop carried object
    var carry = state.EntityManager.GetComponentData<Carry>(playerEntity);
    state.EntityManager.SetComponentEnabled<Carry>(carry.Target, false);
    state.EntityManager.SetComponentEnabled<Carry>(playerEntity, false);
}
else
{
    // pick up nearest available ball
    foreach (var (_, entity) in
        SystemAPI.Query<RefRO<LocalTransform>>()
                 .WithDisabled<Carry>()
                 .WithEntityAccess())
    {
        state.EntityManager.SetComponentEnabled<Carry>(entity, true);
        break;
    }
}

Anti-Patterns

• Calling SetComponentEnabled inside a foreach iterating the same entity — modifies chunk bitmask mid-iteration; causes iterator corruption; always use ECB to defer.
• Calling without completing state.Dependency first — jobs may still be reading/writing the component; triggers safety error.
• Calling on an entity that does not have the component — exception; use HasComponent guard if uncertain.
• Using HasComponent to check if behavior is active — use IsComponentEnabled; HasComponent returns true even when disabled.