Chapter 4 Perspective, Scene Design, and Basic Animation 111
seven. This means from one to four vertices are
hidden from view, depending on where the
camera is located. Also, notice the pixel shading
of the cube shown in the fi gure, Figure 4-22.
To give depth, a shading effect must be added to
differentiate between the fl at surfaces on the
cube. These fl at surfaces are known as faces.
Without this shading effect or contrast, the object
would not be seen as a 3D object. Instead, it
would appear as an irregular 2D shape. The
same cube in a wireframe view shows the
hidden edges and vertices, Figure 4-23.
Scaling
The 3D engine has more work to do than
just render the object on the screen. It must
also move the object in a realistic manner.
Remember how an object in the distance
Edges cannot
be seen
Edge cannot
be seen
A B
C D
Figure 4-22. A—Without pixel shading, some of the edges are not visible. This may make the object look 2D, not 3D.
B—Compare this view to Figure 4-21B. C—In this view, the cube looks like a square, just as in Figure 4-21C, even without
pixel shading. C—A Hoberman sphere demonstrates how vertices can be moved to enlarge an object.
CHEAT CODE: WIREFRAME
Wireframe is a view showing objects as if
they are built with wire, not opaque faces.
In a wireframe view, 3D objects have
visible lines on the edges, but the faces
are invisible. A view with opaque
faces is called a shaded view.
CHEAT CODE: RENDER
Rendering is adding color and shading
to represent an object. In terms of 3D
design, the computer renders 3D
objects to make them appear solid and
then projects the image onto a 2D
surface (the computer screen).