Holy shit my thing actually works! Didn't even need much tweaking. This is a traditional mesh (very simple one right now - a 2x2 quad), skinned with the usual 4-weighted-bones, but it has "thickness", and has a heightfield embedded in it that the pixel shader traces through.
@TomF Nice.
What do you plan to do with it?
@coded_artist Publish it so people can put it in their engines and pipelines.
@coded_artist Parallax mapping is the cheesy equivalent of my raytracer stepping through the heightfield. Again - that's not really the important bit here.