The Model-View-Controller Architecture - Essentials of Interactive Computer Graphics - page 114

back-end programming representation of the drawing area. As will be discussed,
the UIWindow subclasses from the MFC CWnd class and implements the run-time
ReplaceDialogControl() functionality.

GHC and RC. Recall from
Section 4.2: GHC, the graph-
ics hardware context ,repre-
sents the hardware rendering
buffer; and RC, the rendering
context ,

The left side of Figure 5.4 illustrates that the GraphicsSystem object, intro-
duced in Section 4.4 (Tutorial 4.2), will be our abstraction for interfacing with
the graphics API. From our experience working with previous tutorials, we un-
derstand that during graphics API initialization, we establish a correspondence
between the hardware buffer and the UI drawing area. This correspondence is
illustrated by the dotted line connecting the buffer in the GHC and the front-end
UI drawing area. It is this drawing area that a user can direct GUI API mouse
events to and observe graphics API drawings. The center of Figure 5.4 is the
WindowHandler class, where it has a reference to the UIWindow drawing area
and behaves as a view/controller pair for our application. The WindowHandler
has a reference to the RC and works with the GraphicsSystem to present the view
component drawing functionality. For the controller component functionality, the
WindowHandler class supports the mouse events generated from the UIWindow .
The tutorials in this chapter derive and develop the WindowHandler and the
GraphicsSystem classes. Our final ball-shooting program will be based on the
results of these classes. Our main gaols are to understand how the MVC architec-
ture can be supported and how we can achieve code re-use from our design. All
the tutorials in the rest of this topic will be based on these classes.

roughly defines the

appearance.

Tutorial 5.1. Interface to APIs

Tutorial 5.1.
Project Name:
D3D _ ModelView
Library Support:
UWBGL _ MFC _ Lib1
UWBGL _ D3D _ Lib1

• Goals. Become familiar with the UWBGL libraries; more specifically, de-
velop understanding for the structure of the MFC and D3D libraries, and
for the following classes:

- MFC _ UIWindow
- UWBD3D _ WindowHandler
- UWBD3D _ GraphicsSystem

• Approach. Implement a simple interactive graphics application with UWBGL
libraries and examine how the familiar functionality is implemented in the
different classes in the UWBGL .

Figure 5.5 is a screenshot of running Tutorial 5.1. Notice the familiar control
located at the lower-left corner. This is identical to the control form Tutorial 2.8
( CCircleRadiusControls class). In this tutorial, this control manipulates the

Figure 5.5. Tutorial 5.1.