Geometry index inconsistency

The indices of geometries/materials seem unrelated to the order in which they are listed in Blender. Is there a way to control their order? Not being able to predict this order is inconvenient.
I’m improving the random pilot/pedestrian generation code for heXon / OGTatt .

did you try this sorting ?

I was not aware of this option, I’ll try that. Seems like sorting by material is what I would need. Awesome.
Thanks again!

EDIT: Yep, that’s it! Cool; what a relief.
heXon pilots are now saved to and loaded from a file.

EDIT2: This python script does the same for all selected objects:

import bpy

for ob in bpy.context.selected_objects:
    bpy.context.scene.objects.active = ob
    
    bpy.ops.object.mode_set(mode = 'EDIT')
    bpy.ops.mesh.select_all(action='SELECT')
    bpy.ops.mesh.sort_elements(type='MATERIAL', elements={'FACE'})
    bpy.ops.object.mode_set(mode = 'OBJECT')