[Closed] Get material unique handle

it’s too much i think… longer string – slower search. it could be enough:

bit.intashex (random 0 0xFFFFFF)

or you can use LONG if you like and want to be sure.

or you can use:

genClassID [returnValue:<boolean>]

where one part of the result is unique enough

for example:

(filterstring (genClassID returnValue:on as string) "#(,)")[1]

also safe IMHO:

(filterstring (genGuid()) "{-")[1]

Yes, maybe genGuid() is a bit of overkill, will have it into account.

BTW how do you guys choose an AppData index? I just pick a random one between 32.000 and 65.000 and hope for the best, but doesn’t seem very safe. If I happen to pick one used by another tool I could mess the scenes and would be hard to find where is the problem.

the best you can do is to check if ID is already taken (or not). fortunately the system uses AppData rarely. So take a random from high numbers (what you actually do).

i can tell you a little secret… not many people know it and use. the appdata ID might be a negative number

We don’t have to do this. It was just an idea to avoid saving data with the scene (as mentioned by the OP).

That could be a reason. Didn’t know the artist could create new materials or delete old ones.

scenematerials are shuffling all the time… with every file save

i don’t trust the scenematerials at all… many things about it i can’t understand. for example:
reset scene and check:

scenematerials.count

fine … it’s zero

now:

bb = for k=1 to 10 do (box material:(standard()))
scenematerials.count

and:

delete objects
scenematerials.count

hmm… no scene objects but scene materials exist.

Yes. That’s why I suggested cleaning the array up before saving the scene.

Another thing that come to my mind (I am thinking loud here), could be to get the reference nodes using each material and use their inode.handle to create a unique ID? In case of multimaterial, if the sub-materials also need to be stored, the sub-material ID could be added.

Just throwing some more ideas.

At the end AppData seems to be working pretty well, thanks for your suggestions anyway