Impasto discussion

[JL VT]

First of all I want to thank every one who has replied and those who
are about to. For now, I'll be following Boudewijin's advice and focus
efforts just on getting a single impasto layer to work, I can then
test a bumpmapping algorithm until I get a good compromise between
quality and speed. Then I can see how to make 2 of such layers
interact with each other, without necessarily implementing the whole
deal, like an impasto channel for colorspaces.

Based on the results of those experiments and the discussion raised
here, I feel I'll be in a better place to decide which approach to
follow; plus I'll be able to add to the discussion based on my own
experimentation.
So until then, I'll remain silent (tweaking), but that doesn't mean
I'm not closely following all your feedback.

So thanks again for your time  :-)   keep it going.