How can you texture a thruster in Cycles?

With volumetrics, objectID and materialID will still be assigned to the faces of the object…
You may try for example:
-to render the object in a separate layer and use it as a mask.
-or if it’s intensity is high, apply the glow just to bright pixels.

sure there are more ways to get it work, but not with the IDs.

Ahh, gotcha, lack of understanding on my part, I will look at giving it a unique render layer, cheers.