3D Graphics Programming with QuickDraw 3D 1.5.4

Interacting

Often, modeling and rendering are not easily separable, particularly in applications that support interactive 3D modeling. When, for example, the user selects a sphere and drags it using the mouse or other pointing device, the application needs to change the model (reposition the sphere) and render a new image. (Indeed, the application may generate a series of new images to show the sphere changing location as the user drags it.) QuickDraw 3D supports a third main task, interacting with a model (that is, selecting and manipulating objects in the model).

In QuickDraw 3D, interacting involves

determining what kinds of pointing devices are available on a particular computer and possibly configuring one or more of those devices to control items in a 3D model (such as a camera or a light).
identifying the objects in a model that are close to the cursor when the user clicks or drags in the model's image. This is called picking .

QuickDraw 3D supplies an extensive set of routines that you can use to perform these tasks. For complete details, see the chapters "Pointing Device Manager" and "Pick Objects."