You shouldnt have any trouble with HLSL, as you seem to have a good grasp
of vector-mathematics. Thats important. Mine aint so good so I struggle.

I think yOu should ask for HELP with the shader, especially the concepts,
as its not quite the DEEP end of the pool, but it aint the shallow end either.

I will shortly post a bacic concept of how I feel this shader can achieve what you want.

You will be all-right, theres plenty of people to help out. And even I managed
to knock out a few shader myself, but mostly i 'hack' other peoples to suit my
needs.

So if you have any CODING problems, I can help to some degree, but the CONCEPTUAL
side of things Im pretty weak...


And thanks to you too, our banter has helped me get a few things straight in my head,
and pointed out a few 'holes' in my planning...

Best of luck.
And see ya around...