Why is the obtained material ID missing?

[adamhahaEU2VH]

I put all face material IDs in a list to remove duplicates, but there are missing ones

    ID=[]
    for i in range(1,rt.selection[0].numfaces):    #start from 1
        ID.append(rt.polyop.getfacematid(rt.selection[0],i))     #Add material ID to list
    ID=list(set(ID))    #"set" deduplication

 >>> ID

[1, 9, 15, 19, 20, 25]

However, when one of the special faces of the object is selected, its material ID actually shows 6.

why?

(The sample has been uploaded.)

[denisT.MaxDoctor · Accepted solution]

try maxscript :

ids = #{}
for i in $.faces as bitarray do append ids (polyop.getfacematid $ i)

the result ids:

#{1, 6, 9, 15, 19..20, 25}

so the id #6 is used. all is correct

[denisT.MaxDoctor]

---

@adamhahaEU2VH wrote:

(The sample has been uploaded.)

---

Do you know how many users are using 3DS MAX 2022+ today? Post an example a couple of versions earlier than the recent, this will increase the chance that more people will look at it and respond.

[adamhahaEU2VH]

Thank you, I tested it, but why is this happening? Is there a bug in the pymxs module?

[adamhahaEU2VH]

I understand, next time I will save the earlier version as well.

[adamhahaEU2VH]

>>> rt.selection[0].numfaces
1937

$.faces as bitarray
#{1..1937}

The number of faces obtained is the same.

[denisT.MaxDoctor]

the face index is 1 based... so you are missing the last face.  

it should be:

for i in range(1,rt.selection[0].numfaces + 1):
...

[adamhahaEU2VH]

Oh, it turns out that the range function will not go to the last one
Thanks again.