9.5.2

914 • CHAPTER 18
THE SHADERS • 915
Rust
This shader simulates rust on metal surfaces. You choose the colors for the metal and rust using the
gradient. Rust species how much of the material is rusty. Increase the Frequency value for smaller
rust patches.
Simple Noise
This shader creates a random pattern that can be used, for example, for sun surfaces and stone reliefs.
By overlapping several Noise shaders with different amplitudes and frequencies, you can create a
wealth of complex patterns (this is like signal synthesis). The gradient determines the color of the noise
effect. U Frequency and V Frequency determine the neness of the structure. For example, U=1 and
V=1 result in a radial-like pattern, U=1 and V=0.25 give a rather elongated shape. The higher the
value, the greater the detail in that direction.