World
A World owns both an EntityManager and a set of ComponentSystems. You can create as many World objects as you like. Commonly you would create a simulation World and rendering or presentation World.
By default we create a single World when entering Play Mode and populate it with all available ComponentSystem objects in the project, but you can disable the default World creation and replace it with your own code via global defines.
#UNITY_DISABLE_AUTOMATIC_SYSTEM_BOOTSTRAP_RUNTIME_WORLD disables generation of the default runtime world.
#UNITY_DISABLE_AUTOMATIC_SYSTEM_BOOTSTRAP_EDITOR_WORLD disables generation of the default editor world.
#UNITY_DISABLE_AUTOMATIC_SYSTEM_BOOTSTRAP disables generation of both default worlds.
- Default World creation code (see file: Packages/com.unity.entities/Unity.Entities.Hybrid/Injection/DefaultWorldInitialization.cs)
- Automatic bootstrap entry point (see file: Packages/com.unity.entities/Unity.Entities.Hybrid/Injection/AutomaticWorldBootstrap.cs)