Programming UrhoSharp with F#
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How to create a simple UrhoSharp application using F# in Xamarin Studio
UrhoSharp can be programmed with F# using the same libraries and concepts used by C# programmers. The Using UrhoSharp article gives an overview of the UrhoSharp engine and should be read prior to this article.
Like many libraries that originated in the C++ world, many UrhoSharp functions return booleans or integers indicating success or failure. You should use
|> ignore to ignore these values.
The sample program is a "Hello World" for UrhoSharp from F#.
Creating an empty project
There are no F# templates for UrhoSharp yet available, so to create your own UrhoSharp project you can either start with the sample or follow these steps:
- From Xamarin Studio, create a new Solution. Choose iOS > App > Single View App and select F# as the implementation language.
- Delete the Main.storyboard file. Open the Info.plist file and in the iPhone / iPod Deployment Info pane, delete the
Mainstring in the Main Interface dropdown.
- Delete the ViewController.fs file as well.
Building Hello World in Urho
You are now ready to begin defining your game's classes. At a minimum, you will need to define a subclass of
Urho.Application and override its
Start method. To create this file, right-click on your F# project, choose Add new file... and add an empty F# class to your project. The new file will be added to the end of the list of files in your project, but you must drag it so that it appears before it is used in AppDelegate.fs.
- Add a reference to the Urho NuGet package.
- From an existing Urho project, copy the (large) directories CoreData/ and Data/ into your project's Resources/ directory. In your F# project, right-click on the Resources folder and use Add / Add Existing Folder to add all of these files to your project.
Your project structure should now look like:
Define your newly-created class as a subtype of
Urho.Application and override its
namespace HelloWorldUrho1 open Urho open Urho.Gui open Urho.iOS type HelloWorld(o : ApplicationOptions) = inherit Urho.Application(o) override this.Start() = let cache = this.ResourceCache let helloText = new Text() helloText.Value <- "Hello World from Urho3D, Mono, and F#" helloText.HorizontalAlignment <- HorizontalAlignment.Center helloText.VerticalAlignment <- VerticalAlignment.Center helloText.SetColor (new Color(0.f, 1.f, 0.f)) let f = cache.GetFont("Fonts/Anonymous Pro.ttf") helloText.SetFont(f, 30) |> ignore this.UI.Root.AddChild(helloText)
The code is very straightforward. It uses the
Urho.Gui.Text class to display a center-aligned string with a certain font and color size.
Before this code can run, though, UrhoSharp must be initialized.
Open the AppDelegate.fs file and modify the
FinishedLaunching method as follows:
namespace HelloWorldUrho1 open System open UIKit open Foundation open Urho open Urho.iOS [<Register ("AppDelegate")>] type AppDelegate () = inherit UIApplicationDelegate () override this.FinishedLaunching (app, options) = let o = ApplicationOptions.Default let g = new HelloWorld(o) g.Run() |> ignore true
ApplicationOptions.Default provides the default options for a landscape-mode application. Pass these
ApplicationOptions to the default constructor for your
Application subclass (note that when you defined the
HelloWorld class, the line
inherit Application(o) calls the base-class constructor).
Run method of your
Application initiates the program. It is defined as returning an
int, which can be piped to
The resulting program should look like: