Get the "thickness" of an object at render time - Mantra

[snoot 9]

Hi guys, 

I'm attempting to get the thickness of an object and use this to blend between two pbr layers - in this case a sharp refractive layer into a sss-y one.

I could sample an sdf volume on disk and read the thickness from there. But I'm wondering is there a way to do this at render time. For example, catching the position of a ray entering and exiting a surface with lots of sample. 

Any ideas? Example scene much appreciated!

Thanks.

[davpe 183]

hi,

i think you should be pretty much able to get the thickness if you feed an occlusion shader by inverted normals:

 

 

[snoot 9]

Good shout!

I'll give it a go! Thanks @davpe