Materials assigned to a Material Billboard will apparently break horribly - the same Material that worked on a static mesh quad won’t work on a Material Billboard.
It seems that the following information/functionality is not available or only available at random to the Materials:
- WorldPositionWS, ActorPositionWS, …
- TextureCoord[0] with Normalize node attached to it (always 0,0)
- TransformVector, TransformPosition
I intended to use a Material Billboard to add a slight glow to my object that appears even if the main object is off-screen, but it seems I need to write a custom billboard handler for this at the moment.