Du vex function

Contexts: cop , displace , fog , light , photon , shadow , surface

Tags: math

Takes the derivative of the given value with respect to U.

1. float Du(float )

2. vector Du(vector )

3. vector4 Du(vector4 )

Takes the derivative of the given value with respect to U.

In shading contexts, this is the change in the variable over the area being shaded.

You can specify optional parameters to control the computation.