Schlick's Approximation

This node is a simple replacement for the fresnel function and allows for the manual design of energy conserving materials - especially of metals.

• Facing Reflectivity This is the reflectivity of the surface when facing the ray/camera
• Grazing Reflectivity The reflectivity at a grazing angle - when the surface normal is at 90° to the ray/camera
• Exponent This controls the curve of the approximated frensel effect. The higher the value the more pronounced the effect.
• Strength The strength can decrease the overall effect
• No Preprocess Reflectivity Sets the reflectiviy to 0 while LightWave renders a pre-pass. This can speed up interpolated radiosity renders.
• No Radiosity Reflectivity Sets the reflectiviy to 0 if the surface is sampled by a ray used to compute radiosity. This can speed up radiosity renders.

The inputs correspond to the GUI controls.

Function is an alternative way to define the fresnel effect, using one the function nodes available in the node editor to determine the relationship between the viewing angle and the amount of reflectivity.

• Reflectivity This is the computed reflectivity value and is usually connected to the reflection and/or specular input on a material node.
• Inverse This computes the inverse of the reflectivity value and is usually connected to the diffuse input of a material node for energy conservation.

Andrew Comb use Schlick's Approximation alongside other free db&w Tools in his Advanced Shading Tutorial presented at the San Diego LightWave Users Group.