Graphics Programs Reference
In-Depth Information
Figure 19-4:
The final result
after projecting
the detail
This is the entire process for generating normal maps from
modeled geometry. It does have its quirks, but once you learn
those, the process is amazingly simple. With a little practice,
generating normal maps will become second nature to you. To
truly understand normal map creation, however, you need to
understand how they work.
How Normal Maps Fake Detail
Before we talk about normal maps specifically, we first must
talk about surface normals. A
surface normal
is the vector, or
ray, that represents which direction the polygon is facing. This
normal adjusts how light “bounces” off of that surface. Every
vertex stores the normal information for all of its neighboring
polygons. When a polygon shares a smoothing group with a
neighboring polygon, the normals on the shared vertex are
averaged together. This gives the surface a smooth look as it
transitions between the different surface normals.
