9.5.2

828 • CHAPTER 18
MATERIAL EDITOR • 829
Figure 4: Fresnel Reectivity set to a high value (left) and low value (right).
The Fresnel option simulates this phenomenon for you. The Fresnel Reectivity controls the strength
of the Fresnel reections (see Figure 4).
For example, provided Fresnel Reectivity is set to 100%, if you set transparency with RGB values
of 80%, 80%, 80%, the material is 80% transparent and 0% reective when the viewing angle is
90 degrees. With a very low viewing angle, the material is approximately 0% transparent and 80%
reective. If you have entered a reection value in addition to transparency, the reection value is
added to the angle-dependent reection. If Fresnel is disabled, the transparency and reection values
are used as they are irrespective of the viewing angle.
Additive
Figure 5: Additive enabled (left) and disabled (right).
Usually, if the material has a color, the color is automatically reduced with increasing transparency.
This can help to ensure a realistic effect. However, if you don’t want this automatic behavior to take
place, you can enable the Additive option.
If Additive is enabled, the color strength is not reduced automatically and the material may look
unnatural (see Figure 5) unless care is taken. In general, avoid enabling this option.