World

A World contains and wires together Entities and Systems. When something happens, such as adding/removing an Entity or ticking time forward, corresponding methods on the Systems are called. The World also exposes methods to export its Entites as Rooms.

Usage

    var world = new hitagi.World();
    world.register(new hitagi.systems.VelocitySystem());

    var entity = new hitagi.Entity()
        .attach(new hitagi.components.Position({
            x: 0,
            y: 0
        }))
        .attach(new hitagi.components.Velocity({
            xspeed: 0,
            yspeed: 0
        }));
    world.add(entity);

    requestAnimationFrame(animate);
    function animate() {
        world.tick(1000);
        requestAnimationFrame(animate);
    }

Constructor

parameters:
    none

Methods

add: Add an Entity to the World. All registered Systems build the Entity and track it if they want to.

parameters:
    entity - Entity to be added.
return: World, for chaining

remove: Remove an Entity from the World. All registered Systems destroy the Entity and stop tracking it.

parameters:
    entity - Entity to be removed.
return: none

register: Register a System to the World. This builds and tracks all Entities, so should happen before Entities are added to the World if possible for performance reasons.

parameters:
    system - System to be registered.
return: System that's just been registered

deregister: Deregister a System from the World.

parameters:
    system - System to be deregistered.
return: nothing

rebuild: Destroy and untrack an Entity from all registered Systems, then build and track it again. This is used when an Entity goes under a large enough change that it needs to undergo some 'initialisation' again. Setting the 'just' parameter to a Component ID causes only build/destroy methods specific to that Component.

parameters:
    entity - Entity to be rebuilt.
optional parameters:
    just - Component ID of systems to only rebuild in.
return: nothing

clear: Remove all Entities from the World.

parameters:
    none
return: nothing

save: Export all Entities in the World to a Room.

parameters:
    none
return: Saved Room

load: Load a Room into the World. Does not clear the World, so Entities are appended to existing ones.

parameters:
    room - Room to load.
return: nothing