9.5.2

946 • CHAPTER 18
THE SHADERS • 947
Amplitude
Scales the amplitude of the bump algorithm. The appropriate range is 0.0001% to 1,000%.
Octaves
Denes the number of octaves utilized by the noise function dened within the Function drop-down
list. This eld will only be active if the noise function being used utilizes more octaves than one.
Scale
Scales the surface point used in the noise evaluation.
Speed (not all shaders)
This is the animation speed for the noise. The parameter can be animated using the Timeline.
Attenuation
Denes how much the noise algorithm will reduce the detail of the noise when the surface is far
away or facing away from the camera. Appropriate values are 0% for stills and 100% to 1,000% for
animation (it is primarily used to reduce icker in animations).
Delta
Delta is a scaling factor to use in sampling the texture for evaluating slope to be used in evaluating
the bump. This allows you to get very sharp bump with minute detail that is not possible with the
standard static bump delta.
Hard Bump
Uses an implicit algorithm to calculate the bump, producing more realistic dented surfaces. Often used
when creating steel doors with anisotropic highlights to create large dents.
Absolute
Whether or not to fold the noise about its mid level by taking the absolute value of it.