Computes the Fresnel fall-off by using the specified input. The Fresnel fall-off value expresses how closely the surface ...

Computes the Fresnel fall-off by using the specified input. The Fresnel fall-off value expresses how closely the surface normal of the current pixel coincides with the view vector. When the vectors are aligned, the result of the function is 0; the result increases as the vectors become less similar, and reaches its maximum when the vectors are orthogonal. You can use this to make an effect more or less apparent based on the relationship between the orientation of the current pixel and the camera.