9.5.2

898 • CHAPTER 18
THE SHADERS • 899
Step
Intensity is 100% of the Intensity value between Start Distance and End Distance and 0% everywhere
else.
Inverse
Intensity is 100% of the Intensity value at Start Distance and falls off as the inverse of distance and is
clamped to 0% at End Distance.
Inverse Square
Intensity is 100% of the Intensity value at Start Distance and falls off as the inverse of distance squared
and is clamped to 0% at End Distance.
Inverse Cubic
Intensity is 100% of the Intensity value at Start Distance and falls off as the inverse of distance cubed
and is clamped to 0% at End Distance.
Smooth
This gives a smoother falloff when using Proximal for bump mapping or displacement.
Blend Mode
Allows for different possibilities when blending each sampled point together. For instance, the Add
type of blend makes very blown out values, necessitating the user to tweak the values to achieve
a good result. The modes Lighten, Screen, Difference and Exclusion increase the ease of achieving
the desired effect. The Screen blend type is in most cases the best choice, as it yields aesthetically
pleasing results.
Start Distance
The distance at which the object causes 100% luminance.
End Distance
The distance at which the object no longer affects the surface luminance. A value of 100% means
100 m. However, when using Polygon Radius, the percentage value is the same as the polygon radius,
which of course can be different for each polygon.