9.5.2

838 • CHAPTER 18
MATERIAL EDITOR • 839
Figure 2. Figure 3.
These height values are converted into a prole, whose height affects the inclination of the normal
vectors. Although the surface is actually smooth, through the change in the normal vectors an
apparently three-dimensional surface with a bump-like structure is created at render time.
Alpha
Many of CINEMA 4D’s shaders have built-in alpha channels.
An alpha channel enables you to use an image to mask out areas of the material, allowing any
background to show through. This is useful for faking detail in 3D. The idea is to dene areas of
the material that effectively become non-existent so that any underlying materials or objects show
through. A classic example would be a 3D tree. Rather than modelling the individual tree, a picture of
a tree can be added to an object and an alpha used to cut out the shape of the tree.