• Where to find it:

• NodeGraph / Right Mouse Click / Add Nodes / Math / Extension Pack / D /

Partial derivatives of an input transformed into UV Space with an optional U Offset.

This is a stable-for-baking version of a screenspace dFdx, dFdY function call

Some things to keep in mind

• Due to the lookup in UV space, as opposed to window space, results differ from dFdx,dFdy - often for example giving less contrast
  
  
• If the operation is run on the result of an image operation (e.g. paint, bake points etc.) you might encounter artifactng as each pixel compared
  to its neighbor will have a change in value.
  
  

• Offset U

Specifies the U Offset to apply, which can be used to rotate the effect.

Below is an example of taking the partial derivatives of a hemisphere shape, then rotating it by applying a uv offset.
In this case we are using the gl_dFd+UV Node which has both U and V Offset Options.

• F

Specifies the expression of which to take the partial derivative.

• Offset U
  Allows feeding in the U Offset via a Node Input. If mapped the Offset U Option inside the Node are ignored.
  
  

• Output

Return the partial derivative transformed into UV Space, with a U Offset applied