Note: The Scene object was a common object in FlatRedBall in the pre-Glue era, and initially when Glue was introduced. Currently the recommended approach for layout is to use Tiled for TileMaps, Gum for UI, and GlueView for manually placing Entities.
A Scene is simply a collection of different types of objects which can be added as a group. Usually scene creation begins in a tool like the SpriteEditor or TileEditor. The default file type of a scene is .scnx. These are XML files which describe a scene. These scene files can be loaded by FlatRedBall XNA applications either through the content pipeline or directly from file.
Scenes can include the following objects:
For information on file placement when loading from file, see the Managing Files tutorial.
Loading a Scene From File
You can load a Scene just like any other file (such as a .png) though the FlatRedBallServices class:
Files Used: SplashScreen.zip
string fileName = "SplashScreen\SplashScreen.scnx"; string contentManagerName = "SomeContentManagerName"; // use the Screen's ContentManager if in a Screen Scene scene = FlatRedBallServices.Load<Scene>(fileName, contentManagerName ); scene.AddToManagers();
The Scene adds all of its contained objects to the appropriate managers through the AddToManagers method. Prior to calling AddToManagers all objects referenced by the Scene are stored in memory but they are not managed or drawn.
Notice that the last line calls the Clear method. The reason for this is because Scenes holds most referenced instances in AttachableLists which have two way relationships. If the reference to the scene object is lost but it is not cleared, all referenced IAttachables will continue to reference all AttachableLists held in the Scene. While this is not a critical problem, it can increase memory use slightly and reduce the speed of the garbage collector. For more information on two-way relationships and an explanation on why AttachableLists must be cleared, see the AttachableList entry.
Calling the Clear method will not remove all objects from the engine, so you can call this after adding eveything to the engine with the AddToManagers call.
Note: For more information on how to add files to Visual Studio and how to control how they are built, see the “adding files to your project” page.
Using the Content Pipeline
For information on loading Scenes through the content pipeline, see the Using the FlatRedBall XNA Content Pipeline wiki entry.
Scenes and PositionedModels
The Scene class can contain references to PositionedModels. To load a .scnx that includes model references (.x or .fbx) the .scnx must be loaded through the Content Pipeline instead of from-file.
Removing a Scene
Previously removal was done through the SpriteManager As of September 2007 Scenes can remove all contained items from the engine by calling RemoveFromManagers. The following code would remove all items contained in myScene:
Saving a Scene
See the Saving a .scnx wiki entry.
Getting References to Objects Inside Scenes
After creating a Scene in the SpriteEditor, a common task is to store some of the objects contained in the Scene as class-level instances for easy access. For example, a Scene may contain a Text object which will needs to be modified to display the player’s score as he earns points. Or perhaps a Scene contains a Sprite which represents a door that the player must touch to move to the next level.
To retrieve references to objects in a Scene in code, the FindByName method can be used. The FindByName method as a method in the list properties of the Scene. The following code shows examples of how to get a reference to various objects in the Scene:
// Assumes that mScene is a valid Scene Sprite doorSprite = mScene.Sprites.FindByName("Door"); SpriteFrame button = mScene.SpriteFrames.FindByName("Button"); Text scoreText = mScene.Texts.FindByName("Score");
Of course, the Scene must contain objects with the same name as what is passed in the FindByName method. These names will be set in the SpriteEditor.
- FlatRedBall.Content.SpriteEditorScene – Provides the ability to convert Scenes to .scnx files as well as to to manually load .scnx files.
- Setting the Camera to match the SpriteEditor – Discusses how you can make Scenes in your game work exactly like they do in the SpriteEditor.