Displacement problem

[stef.thomas]

I'm trying to use displacement on a glass to make a raised pattern but can't figure out how to make it so that both the inner wall and outer wall of the glass both displace towards the outside. At the moment all that happens is that the displaced part causes a thickening of the glass as both sides move in opposite directions. How would I go about setting it up to get the desired result? Thanks in advance for any help.

[nils_p]

I'm not sure but I think displacement pushes the objects' normals. That's almost always outward the object.
So you have to unwrap your model and for the insides you have to have the same displacement map but inverted(negative) and I'm thinking also mirrored.

Never tried this before so good luck

[stef.thomas]

Thanks, I had a feeling I'd have to map the inside and outside differently. Looks like it's time to learn the UVW Unwrap modifier

[3DMK]

Flip normals-Geometry

You could also try to flip the normals of the inside polygons of the glass geometry.
That way you don't have to know anything about unwrapping uv's

Just remember to tick the 'Reflect on back side' option otherwise it won't reflect on the inside of the glass once you've flipped the normals

Hope this helps

[stef.thomas]

Messing with the normals caused a heap of problems so I just went with the unwrapping route which worked a treat. Thanks guys!