How to avoid decals being "projected" through objects?

So when I apply a decal on a solid, the decal gets “projected” right through the object and gets smacked to any other surface(s) in its normal direction, as shown in the picture below. How can I avoid that?

Fig 1. The decal on the inside of the container should not be there (visible on the inside, that is).

// Rolf

Hi Rolf - you need to separate the inside from the outside of the part, as far as I know.


Yes, I understand. Therefore I made a 5 mm thickness on that plate. Here the clipping plane shows the thickness. And the property inspector confirms this i a “closed polysurface”.

// Rolf

Adding thickness does not separate the parts. It is still one object.

This is currently how decals work: one object that has multiple sides with faces facing the same direction will get the planar decal if it hits the decal in that direction (forward, backward or both directions).

What @pascal means is that your inside and outside of the object need to be two separate objects for this to work with the current decal approach to work.

Ok, I will have to make “sign plates” for each decal then. No big deal, I just thought it was possible to do without.

// Rolf

If you do that it’ll be more efficient to use texture mapping instead of a decal. It’ll result in a simpler shader graph.

At least for Raytraced/Rhino Render.