Virtual Scene Runner

warning

This feature is provided in the messenger-extra package.

Users may want to run multiple scenes simultaneously, or use stacked scenes (which can remember your previous scene automatically).

Messenger provides several functions to allow users to run scenes in user code, like running "virtual machines".

The API is very simple, in Messenge.Scene.VSR:

{-| Virtual Scene Runner
-}
type alias VSR userdata scenemsg =
    { env : Env () userdata
    , scene : MAbstractScene userdata scenemsg
    }

{-| Update the VSR.
-}
updateVSR : VSR userdata scenemsg -> UserEvent -> ( VSR userdata scenemsg, List (SceneOutputMsg scenemsg userdata) )
updateVSR vsr evnt =

{-| View the VSR.
-}
viewVSR : VSR userdata scenemsg -> Renderable

So a VSR is just a Env with an abstract scene.

updateVSR and viewVSR are very straightforward. They are used to update and view the virtual scene.

But how to get the scene?

In global components, the common data GCCommonData is just MAbstractScene so we could get it easily.

For normal user code, if there is a scene defined as:

scene : SceneStorage UserData SceneMsg

Users could generate an abstract scene by initialize it with an initialization message and environment, since its type is:

type alias SceneStorage userdata scenemsg =
    Maybe scenemsg -> Env () userdata -> MAbstractScene userdata scenemsg