Attributes and Behaviors of Primitives - Essentials of Interactive Computer Graphics - page 153

- WindowHandler subfolder. Contains IWindowHandler ,and Window
Handler.h/.cpp , the abstract and API-independent definition of the
WindowHandler class. These file are identical to the files from the
previous library ( UWBGL _ D3D _ Lib3 ).

• Header Files folder. Contains the header files that support D3D API-

specific functionality.

• D3D Files folder. Contains files that define D3D-specific classes. For ex-
ample, we have already seen D3DWindowHandler.h/.cpp implementing
D3D-specific WindowHandler functionality.

- D3D_DrawHelper subfolder. Contains D3DDrawHelper1.h/.cpp .
These two files implement D3D-specific drawing functionality for the
DrawHelper abstraction.

This new subfolder replaces the previous

D3D_Geoms subfolder.
- D3D_GraphicsSystem subfolder. Contains D3DGraphicsSystem.h/
.cpp . These files implement the abstract graphics API. These files are
identical to the ones from the previous library.
- D3D_WindowHandler subfolder. Contains D3DWindowHandler.h/
.cpp . These files implement the view/controller pair for the D3D
API. These files are identical to the ones from the previous library.

DrawHelper class. The DrawHelper class defines drawing attributes and pure
virtual drawing functions. As we can see from Listing 7.1, under label A are
the drawing functions that do not do anything. Under label B are the functions
and the instance variables that are capable of recording the desired attributes for
drawing. Label C shows examples of the attribute-setting functions. To support
graphics API-specific drawing commands, each graphics API should subclass
from DrawHelper and override the drawing functions. Label D shows that the
DrawHelper class has support for modeling transformations. We will discuss

working with the transformation functions in Chapter 9.

OGLDrawHelper . Similar to
the D3DDrawHelper class, the
OGLDrawHelper class imple-
ments OpenGL-specific prim-
itive drawings.

D3DDrawHelper class. The D3DDrawHelper class subclasses from the Draw
Helper class to implement D3D-specific attribute setting and primitive drawing.
Listing 7.2 shows the D3DDrawHelper class override the drawing and attribute-
setting functions.

The implementation of the attribute-setting functions (e.g.,

RC. Rendering context. Re-
call that this context contains
the entire rendering state.

SetFillMode() ) shows that we do indeed invoke the D3D GraphicsSystem to
set the render state of the D3D RC. Listing 7.3 shows the draw functions for line