Refraction

Define a value for the refractive index. If a ray of light strikes a surface with settings for Transparency and Refraction, the ray is refracted. The refractive index determines how much light is bent, or refracted, when entering a surface. Refraction only applies when you render.

Examples

Material	Refractive index
Vacuum	1.0
Air	1.0
Ice (water)	1.31
Water	1.33
Glass	1.44 - 1.9
Acrylic glass	1.491
Benzene	1,501
Crown glass	1.51
Flint glass	1.613
Diamond	2.417 - 2.419

If you assign Transparency to a surface, the program automatically uses Fresnel reflection. This method considers the viewing angle (the angle between the camera and the surface). If you look at a glass pane at a viewing angle of 90 degrees, you will see that the pane hardly reflects any light at all. So the light passes through the pane almost completely. But if you look at the pane at an acute angle, you will notice that the pane reflects more light. Consequently, transparency and reflection depend on the viewing angle.

For example, if you set Transparency to RGB values of 80%, 80%, 80%, the transparency of the material is 80% and it reflects 0%. On the other hand, if the viewing angle is very flat, the transparency of the material is 80% and it reflects 80%. If you have defined a reflection value in addition to transparency, the program will add this value to the reflection defined by the viewing angle.