The goal is to only show a decal on one side of an object. Preferably with an interface that is easy to manipulate and experiment with position.

I found this example here that accomplishes the goal but it has problems too
https://render.otoy.com/forum/download/file.php?id=61318&mode=view

This ...

Hey guys I appreciate the reply but it appears the Side node is referencing polygon normal, toggling which normal side the texture is to be displayed on - correct?

(for reference, C4D is setup to say "when the Flat texture's Z axis collides with polygon normal's Z, it renders that face only. The ...

Applying a texture to a cube using C4D standard render you can set the texture to:

Projection: Flat
Side: Front
And that texture will only be displayed on one side of the object. (the viewport will display incorrectly both sides textured, but will render only one side textured)

aoktar has ...