Note: This documentation is for the old 1.0.0 version of A-Frame. Check out the documentation for the current 1.4.0 version
A system, of the entity-component-system pattern, provides global scope, services, and management to classes of components. It provides public APIs (methods and properties) for classes of components. A system can be accessed through the scene element, and can help components interface with the global scene.
For example, the camera system manages all entities with the camera component, controlling which camera is the active camera.
A system is registered similarly to a component.
If the system name matches a component name, then the component will have a
reference to the system as
|data||Data provided by the schema available across handlers and methods.|
|schema||Behaves the same as component schemas. Parses to
A system, like a component, defines lifecycle handlers. It can also define methods intended to be public API.
|init||Called once when the system is initialized. Used to initialize.|
|pause||Called when the scene pauses. Used to stop dynamic behavior.|
|play||Called when the scene starts or resumes. Used to start dynamic behavior.|
|tick||If defined, will be called on every tick of the scene’s render loop.|
An instantiated system can be accessed through the scene:
Registered system prototypes can be accessed through
Systems can help separate logic and behavior from data if desired. We let systems handle the heavy lifting, and components only worry about managing its data through its lifecycle methods:
There is no strict API for defining how systems manage components. A common pattern is to have components subscribe themselves to the system. The system then has references to all of its components: