often I render large interior spaces with simple glass (no refraction, reflection only). Often I need to see the objects behind the glass at the material mask without any influence of the glass material. Please add an option or a way to set a material ID to invisible. An easy way could be to use the ID color white as “invisible” marker like black is a marker for “automatic color”. I hope it’s possible to implement.
Found a small trick to keep the influence of the invisible material id low - set it at color (1,1,1). So, the automatic material ID color is disabled and a nearly black color is used. In my case I have an invisible wall with some objects is in the foreground and it works quite good.