Method OnUpdate

OnUpdate()

Implement OnUpdate() to perform the major work of this system.

Declaration

protected override void OnUpdate()

Overrides

SystemBase.OnUpdate()

Remarks

By default, the system invokes `OnUpdate()` once every frame on the main thread. To skip OnUpdate if all of the system's [EntityQueries] are empty, use the [RequireMatchingQueriesForUpdateAttribute]. To limit when OnUpdate is invoked, you can specify components that must exist, or queries that match specific Entities. To do this, call RequireForUpdate<T>() or RequireForUpdate(EntityQuery) in the system's OnCreate method. For more information, see [ShouldRunSystem].

The [Entities.ForEach] and [Job.WithCode] constructions provide convenient mechanisms for defining jobs. You can also instantiate and schedule an IJobChunk instance; you can use the [C# Job System] or you can perform work on the main thread. If you call EntityManager methods that perform structural changes on the main thread, be sure to arrange the system order to minimize the performance impact of the resulting [sync points].

 [sync points]: xref:concepts-structural-changes
 [C# Job System]: xref:JobSystem
 [Entities.ForEach]: xref:Unity.Entities.SystemBase.Entities
 [Job.WithCode]: xref:Unity.Entities.SystemBase.Job
 [EntityQueries]: xref:Unity.Entities.EntityQuery
 [RequireMatchingQueriesForUpdateAttribute]: xref:Unity.Entities.RequireMatchingQueriesForUpdateAttribute
 [ShouldRunSystem]: xref:Unity.Entities.ComponentSystemBase.ShouldRunSystem