Hello,
I’m writing a script that should store a list of materials, but I can’t find a way to get an unique identifier of the scene materials so I can recover them when I open the scene afterwards.
For objects I can use the “inode.handle” property, but it’s not available for materials. There is the “anim handle” property on materials to get an unique handle, but it changes each time the scene is loaded. Can’t use material names because I can’t guarantee them to be unique.
The only solution that I can think of is adding a custom ID property to the materials using AppData, but I would prefer a native way to get a material by ID without adding extra properties and having to loop all the materials to find the ones to be used.
Any idea? (Should work in 3dsMax 2017)
You answered your own question, and found the right solution.
There is no unique lifetime handler for material instance. There is an anim handle which is unique for current scene only.
The only way to tag a material is to add some unique identifier, and the best place is its AppData.
There is nothing to add to all these true statements.
There are only two questions – how to organize this tagging, and how to find an instance by id quick.
O well, I was hopping there would be a more straightforward way to do it to keep things simple and fast
If I have to do it with AppData I guess the easiest way to get an unique tag could be assigning a UUID to the materials with “getGUID()”, and search for them looping the scene materials like:
fn getListMaterials idList = (
for m in sceneMaterials where (
findItem idList (getAppData m SCRIPT_APPDATA_ID) > 0
) collect m
)Don’t know if I can get them faster…
Thanks for letting me know I’m not missing something obvious Denis, if you aren’t paid by Autodesk you should, far better support
I don’t understand this idea… Do you want to group ids for some material classes (types)? If so, there is a faster way to find them later. Instead of collection ids in separate lists, use two-parts id, where the second part for example a type identifier, and first part is unique id. (similar to how class id works)
yep… but they don’t pay.
The intention of this function is to retrieve the scene materials that where chosen by the user when the script is opens anew.
Each material will have an unique ID, don’t see a need to group them at the moment.
Heh, short sighted by AD part.
what is idList?
the most difficult issue is to assign new ID for every newly created or cloned materials. There is a scene callback – #mtlRefAdded. But it’s not easy to handle. It fires many times and sometime at not really “added” moment. Also as I remember there is an issue with material’s Undo/Redo operations. Which sometimes are not following with expected callbacks.
How about working with the sceneMaterials array?
Cleaning it up and sorting on a pre-save scene callback and then using the indexes as IDs?
It’s a string list of the ID’s of the material selection to restore. The ID’s are UUIDs created with genGuid() to avoid repetitions.
Mmm, do you mean that when a material is cloned it’s AppData is copied to the new material? I have to test it.
The script I’m doing has a “save” function that gets the user-selected materials and retrieves their ID from AppData, in case there isn’t any it generates a new one using genGuid(). So I wasn’t worrying too much about them while the user works with the scene, just during save (materials->idList) and load (idList->materials). But I see there could be problems if AppData gets duplicated… that’s why I wanted to keep things simple
The good thing about AppData is – it’s NOT duplicating with clone It wipes from newly created node (material i your case). What is good for you.
I’m not sure I can guarantee that the indexes will be the same when the script loads the materials again. If the user creates a new material and opens the script the list could change.
Good.
My load and save functions seem to be working fine on the simplest cases, but have to test is a lot more (create / delete materials, using XRefs, MultiSub materials, …), I’m sure will find some way to break it