I'm trying to shortened the length of a transmapped hair by making a shader that can be applied. I normally shorten hairs with either a morph or by shortening the transparency map, but I wanted to do this with a shader. I tried what is shown below which moves the transparency map up and then covers the overlap at the bottom with a black band. I did this for both the texture map and the transparency map although it should only be required for the transparency map. This shader looks right in the preview windows but the render shows black hair where the transparency map should be making the image clear. I know this hair can be shorted by manipulating the transparency map because I did it by making a new map outside Poser and loading it in. It seems like the shader below should work too. I'm showing my ignorance here, but I think if this could be figured out, it could be easily applied to a lot of hairs and might help others too.

 

Thanks