Displacement per face on a polysurface

Is it possible to assign a displacement on just a face of a closed polysurface?
It could be in Rhino or also Vray.

Thanks

should be possible, subselect the face and add your material

I ran some additional tests, and it seems that in V-Ray, it’s not possible to apply displacement to a single face of a closed polysurface. Is that correct, @Nikolay ?

In Rhino, it is technically possible, but there are still some bugs. For instance, if you adjust the black and white points of the displacement map to change its intensity, the result won’t update immediately. To see the changes, you have to temporarily switch the displacement bitmap to a different one and then reapply the original map. This seems like a bug.

I couldn’t add displacement to a single face only. Is there some trick I need to employ?
V-Ray takes the displaced mesh directly from Rhino via something called CRM2. So whatever the CRM2 had calculated for that particular object - V-Ray will use it as-is. This is a generic mechanism for all geometry modifiers - shut lining, displacement, edge trimming, etc… V-Ray doesn’t actually (need to) know whether there is a modifier or not - it just asks the CRM2 to deliver the custom mesh and that’s it.

Speaking on CRM2, there is currently a problem with it and interactive rendering with V-Ray. Is is a known issue for quite some time, and there is no good solution. Simply the CRM2 delivers the wrong mesh. This is due to the fact that the displaced mesh is calculated in a multithreading fashion, but the “done” message is send before they are all done. There was a talk on that with McNeel, and it was decided how to implement the interactive support.
So basically you need to wait for it. But it is coming for sure

I believe @andy is currently working on that.

I already have a patched version of Rhino and a demo code. It should be fixed for the beta