[Closed] materialIDs

Can someone tell me how i would go about assigning materials based on material id’s.
i am assigning them like this
msh = mesh vertices:Vert_array faces:Face_array materialIDs:Mat_ID_Array
say for instance I have a pyramid
the bottom square is material id 1
the 4 triangles are all material id 2
so now ideally i would create a multi material
then assign all faces with material id1 to the first slot in that material
then assign all faces with id 2 to the 2nd material slot.
Thanks again for any help i have been searching to try to find this without luck

Edit.
Ok i feel stupid when i assign a multi material it automatically assigned the material in that order.