Delta Engine の Sample/Empty Game を F# に移植

EmptyGame.fs

open DeltaEngine.Core
open DeltaEngine.Datatypes
open DeltaEngine.Platforms

type EmptyGame() =
    let mutable fadePercentage = 0.0f
    let mutable currentColor = Color.Black
    let mutable nextColor = Color.Black

    let SwitchNextRandomColor() =
            currentColor   <- nextColor
            nextColor      <- Color.GetRandomColor()
            fadePercentage <- 0.f

    let run (window:Window) = 
        fadePercentage <- fadePercentage + Time.Current.Delta
        
        if fadePercentage >= 1.0f then
            SwitchNextRandomColor()

        window.BackgroundColor <- Color.Lerp(currentColor, nextColor, fadePercentage)

    interface Runner<Window> with
        member this.Run(window) = run window

    member this.Run(window) = run window        

module Program =
    [<EntryPoint>]
    [<CompiledName("Main")>]
    let main argv = 
        let app = new App()
        app.Start<EmptyGame>()
        0