Graphics Programs Reference
In-Depth Information
Figure 19-5: No smoothing groups vs. smoothing groups
with normals shown
Note:
If you want to look at the normals of the surfaces in the
models you've created, just apply the Edit Normals
modifier. This modifier not only allows you to look at
them, but also to average any normal you like. It's not a
tool you'll use every day, but you may find a use that
many have not thought of.
The key to how a normal map accomplishes this effect is in its
name. In the most common use of normal maps, called “tan-
gent space normal maps,” the texture map literally modifies
the surface normal on a per-pixel basis. That is, each pixel on
the texture stores a value to adjust how the light reacts to it.
That sounds like it would take a long time to render, does it
not? Well, not nearly as long as rendering and tracking a
model with 3 or 4 million polygons!
Here's how the normal map itself stores that data.
Figure 19-6 shows what you get when you render out a
normal map. (To see the following images in color, go to
http://www.wordware.com/files/3dsmax2008 and download
the companion files.)
