Hi, I got Carrara 1.1 off a cover disk and I'm astonished. It was immediately useful because I wanted a corrugated iron water tank. I made one by modifying a formula from Jean Pellegri's pages (link found here - merci bien) Here is the formula if anyone wants it. d=4;e=2; p=2*PI*(u-0.5); q=3*(v-0.5); z=e*q; x=d*cos(p)+sin(z*15)*cos(p)/15; y=d*sin(p)+sin(z*15)*sin(p)/15; My question is if anyone has ideas how to put shaders on it. What I want is a very rusty old tank. I would probably shade it globally with a texture map of galvanised iron. The tricky part is the rust which I want to put on only the upper side of the corrugations (or would it be the lower side - now I doubt?). I've been trying to do this with slope from the smart pack but can't work out how to blend the slope effect with a colour or texture. It would also be very irregular and spotty. Any ideas appreciated. George

Attached Link: http://home.swipnet.se/JEK/tutorial/tutor.html

This link may give you some ideas.

seems my reply didn't get posted? Try again. The link is brilliant thanks. I'm nearly there using slope instead of elevation. That pic shows the remaining problem - the shader works fine on a sphere but on my formula generated tank it shows all the polygons. I've tried every combination of tiling and get no better. Will try again later with dirrerent textures, but if you see something obvious I'm doing wrong, give us a hoy. Thanks again George

It looks like you're using a bump channel in the shader. Try it without. Mark

Try using elevation instead of slope.

yes it's a bump problem. Elevation works, too, but just rusts the bottom of the tank. Thanks to you both George