I have a question about user defined data, because I am not sure if I understand COLLADA correctly. I would like to associate some unique id with each face and vertex in a <mesh>. I don’t care what form the unique id is in: it could be integer, a string, anything (as long as I ensure that it is unique, I can map it to anything I want).
Any program that reads COLLADA files does not have to understand this data, but simply associate it with the face, and ensure it “stays with” the face even if the program renumbers the faces from how they were originally implicitly numbered in the .DAE file. This way I can ensure that my custom face or vertex properties (stored either in another file, or in an <extra> segment) have a meaningful way to refer back to the face or vertex they belong to.
Is this possible? From my understanding of it, it seems like the barrier where user-defined things are not allowed is that anything which does not have a predefined SEMANTIC associated it with (i.e., not POSITION, INTERPOLATION, COLOR, etc.) is not guaranteed to be preserved by conformant COLLADA tools. On the hand, I have this feeling that you must be able to at the very least associate an integer with a face or vertex, or the idea of DCC does not really make sense. Is there a way to do it?
Thanks for your help!