Adobe ATMOSPHERE User Manual page 248

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APPENDIX D
The scene hierarchy is rather like a folder hierarchy in the operating system. Objects may be thought to be contained
within nested folders. However, in addition to storing an object, the scene hierarchy also affects the 3D position
of objects displayed in the scene. Moving a parent object will also move the child objects if they are "attached to
parent" (true by default), and the position of objects will be in "parent relative" coordinates. If the objects are not
attached to parent (by setting to 'false' in the API), then their position is in absolute world space coordinates. To aid
the positioning of objects in the API, there are properties on objects that give the "world space position" directly for
an object independent of where it is in the scene hierarchy. By default in the Atmosphere application, all objects are
attached to parent.
The World
At the top of a scene hierarchy is the world which is a container of type "SceneGroup" that has listed within it
child objects that are other scene objects. The World is accessed within the JavaScript API using the global variable
"theWorld". The world will contain the globals "theActor" and "theStage".
The Actor
The actor (the global "theActor") represents the local user of the application. It has various properties that represent
the motion of the Actor as he or she moves through the 3-D world. There is a built-in standard navigation scheme
that may be partially or fully disabled and replaced with a motion that is determined by a JavaScript. (The control of
the Actor motion and view of one's avatar are discussed in more detail in a later section.)
The Stage
The stage is a container for all content loaded from fi les when interacting with a world (excluding the actor and
remote actors). The stage may directly contain solid objects, surface objects, Viewpoint objects, etc., as well as other
scene groups with their own nested content. When a model is added to the world using a script to open an .AER fi le,
it is added to the stage by default.