XTreme Slopes

[ProjectX]

Is there any way to limit a shader/population etc. to slopes that are upside down?

e.g. I have some wacky displacement (twist and shear) and so I have an overhang. What I want to do is put a certain shader on the underside of this overhang. Is this possible?

EDIT: also - what if you have several over-hangs that actually overhang each other? would it be possible then, since you'd effectively have two upside down surface in the same XZ space.

[old_blaggard]

Well, when you think about it, upside down surfaces are essentially surfaces with slopes higher than 90 degrees.  I don't think the issue you described in your edit would pose a problem, but give it a go and let us know how it turns out .

[ProjectX]

K, I'll be back in half an hour with the results.

Yup, just set your shader to be on slopes greater than 90 degrees. Cheers for the help!