Node for inline generation of RGB normal from greyscale height input

I use FF constantly for rapid pixel shader prototyping, and one thing I have found myself wanting is a way to generate a normal map inline in the node network (most often I am splitting the red and green channels of a normal map to be used as the horizontal and vertical directions of an offset node).

I realize that the refraction node could be used similarly and could take greyscale height input and generate a normal map behind the scenes; the reason I prefer to use the offset node is that the offset node allows me to reproduce my FF results in HLSL with 100% accuracy. Also, there are other times that having -1..1 data for the shape of the slope of the height in two different directions would be nice.

I got 66% of the way there- if you scroll to the bottom: http://www.filterforge.com/forum/read...0&TID=5030

The post by "sphinx" gets the red and green channel basically perfectly. No such luck on the blue channel though.