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Right now, all 3D widgets inherit from OgreWidget, a bare-bones integration class that wraps an Ogre::RenderWindow inside a QWidget. This is adequate for highly specialised or simple widgets, but for something like MapView, containing multiple geometric objects each needing custom behaviour (context menus, drag & drop, selection), there needs to be another layer to facilitate this in a general way.

Qt features a graphics view framework that separates scenes (QGraphicsScene) and views (QGraphicsView), allowing multiple views to show off different parts of the same scene in a similar way to the Qt's model/view framework. Scenes are made up of scene items (QGraphicsItem). Many events are forwarded from the view to the scene and into the item underneath the cursor, allowing items to have customised behaviour through subclasses.

Creating an equivalent for 3D scenes would bring about many benefits. The MapView class would become a small subclass of the view class. The Tool classes could become virtual scene items with infinite bounds (to receive all events before anything else), or otherwise stay as modes of MapView. Individual clickable items (map objects) would be represented as scene items, completely obsoleting the hacked together MapGeometry class and streamlining additions and modifications to the way geometry can be interacted with.

New classes:

• SceneView - A subclass of OgreWidget, this class holds an Ogre::Camera from a Scene, and uses it to translate incoming mouse events to the scene's world space.
• Scene - Encapsulates an Ogre::SceneManager and holds SceneItem objects. Forwards incoming events from SceneView objects to the appropriate SceneItem object (usually the one below the cursor). Tells SceneView objects to repaint themselves when scene changes.
• SceneItem - An abstract class that receives events from its Scene, provides a bounding box, and informs Scene of any changes to its bounding box.

Changes:

• MapView - Becomes a subclass of SceneView instead of a direct subclass of OgreWidget.
• MapGeometry - Instead of staying as a monolithic class that creates, updates and holds, all the geometry in the scene, the contents of this class can be moved into various SceneItem subclasses.