FSharpFNAExample.fs

open System

open Microsoft.Xna.Framework
open Microsoft.Xna.Framework.Input
open Microsoft.Xna.Framework.Graphics




type FNAGame() as self = 
    inherit Game()
    let mutable gdm = new GraphicsDeviceManager(self)
    let mutable keyboardPrev = new KeyboardState()
    let mutable mousePrev = new MouseState()
    let mutable gpPrev = new GamePadState()
    let mutable batch: SpriteBatch option = None 
    let mutable texture : Texture2D option = None

    do 
        self.Content.RootDirectory <- "Content"
        gdm.PreferredBackBufferWidth <- 1280;
        gdm.PreferredBackBufferHeight <- 720;
        gdm.IsFullScreen <-false;
        gdm.SynchronizeWithVerticalRetrace <- true
        
    override this.Initialize() =  base.Initialize();
    
    override this.LoadContent() = 
        batch <- Some (new SpriteBatch(self.GraphicsDevice))
        texture <- Some (self.Content.Load<Texture2D>("FNATexture"))
        base.LoadContent()
        
    override this.UnloadContent() = 
        match batch with
        | Some x -> x.Dispose()
        | None -> ()

        match texture with
        | Some x -> x.Dispose()
        | None -> ()

        base.UnloadContent()

    override this.Update gameTime =
        let keyboardCur = Keyboard.GetState()
        let mouseCur = Mouse.GetState();
        let gpCur = GamePad.GetState(PlayerIndex.One);

        if (keyboardCur.IsKeyDown(Keys.Space) && keyboardPrev.IsKeyUp(Keys.Space)) then
            System.Console.WriteLine "Space bar was pressed!"

        if (mouseCur.RightButton = ButtonState.Released && mousePrev.RightButton = ButtonState.Pressed) then
            System.Console.WriteLine "Right mouse button was released!"

        if (gpCur.Buttons.A = ButtonState.Pressed && gpPrev.Buttons.A = ButtonState.Pressed) then 
            System.Console.WriteLine "A button is being held!"

        keyboardPrev <- keyboardCur;
        mousePrev <- mouseCur;
        gpPrev <- gpCur;
        base.Update(gameTime);


    override this.Draw gameTime =
        self.GraphicsDevice.Clear(Color.CornflowerBlue)
        (Option.map2 (fun (batch : SpriteBatch) (texture: Texture2D) -> 
            batch.Begin();
            batch.Draw(texture, Vector2.Zero, Color.White)
            batch.End();
            ) batch texture)

        |> ignore
        
        base.Draw(gameTime);


[<EntryPoint>]
let main argv =
    printfn "Hello World from F#!"
    use g = new FNAGame()

    g.Run();
    0 // return an integer exit code