Game Development Reference
Converting from Screen
Space to World Space
A mathematician is a device for turning coffee into theorems.
When working with standard applications, users are accustomed to clicking on a
control or widget and having some degree of interaction with the control. Take a
push button, for example; users click on a push button and a visual cue is used that
presents the button in a depressed state, and the button launches an on-click event
that performs some action. Users are also accustomed to this same level of inter-
action with 3D applications.
Many 3D applications have dialogs that can modify and manage data without the
need to interact with the scene, but visual interaction is much easier and faster to
perform than clicking through dialog after dialog. For example, 3D applications
typically allow the user to reposition objects within a scene by using the mouse
and by typing in coordinates in a dialog box. It does not take a lot of thought to
figure out which method is faster and more productive. If using the mouse is eas-
ier and more productive, why bother with field-driven dialog boxes at all? Using
the mouse is quick, but typing coordinates into a dialog is much more precise than
using the mouse and trying to coerce an object into a specific location.