Removing all material slots in one go

Question

I need some help in removing all material slots in one go using a python script. I am able to use this, would prefer to ave all removed.

bpy.context.object.active_material_index = 0
bpy.ops.object.material_slot_remove()
bpy.context.object.active_material_index = 1
bpy.ops.object.material_slot_remove()
bpy.context.object.active_material_index = 2
bpy.ops.object.material_slot_remove()

You'll find some good answers here – Robin Betts Jul 29 '19 at 17:07 — Robin Betts, Jul 29 '19 at 17:07

score 11 · Answer 1 · edited Jan 29 '24 at 18:48

11

You can set the index of the list to 0, iterate through all slots and override the context of material_slot_remove().

Blender 3.2+

import bpy
from bpy import context
for obj in context.selected_editable_objects:
    obj.active_material_index = 0
    for i in range(len(obj.material_slots)):
        with context.temp_override(object=obj):
            bpy.ops.object.material_slot_remove()

Blender 2.8+

import bpy
for obj in bpy.context.selected_editable_objects:
    obj.active_material_index = 0
    for i in range(len(obj.material_slots)):
        bpy.ops.object.material_slot_remove({'object': obj})

edited Jan 29 '24 at 18:48

p2or

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answered Jul 29 '19 at 13:04

brockmann

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Can you elaborate the part of overwriting the context? – Mike W Apr 19 '20 at 17:09
1

Further reading: poll() failed, context incorrect? @MikeW – brockmann Apr 19 '20 at 18:40

score 6 · Answer 2 · answered Jul 29 '19 at 13:05

import bpy #import the blender python library
for x in bpy.context.object.material_slots: #For all of the materials in the selected object:
    bpy.context.object.active_material_index = 0 #select the top material
    bpy.ops.object.material_slot_remove() #delete it

score 4 · Accepted Answer · answered Jun 15 '22 at 11:56

4

You can also remove all material slots without calling the operator at all, so you don't have to bother with indexes:

bpy.context.object.data.materials.clear()

In general, I would always try to avoid calling operators unless they do something very specific that is difficult to achieve via calling usual API functions.

answered Jun 15 '22 at 11:56

Febulix

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That would remove the materials, not the slots. – Yousuf Chaudhry Jun 15 '22 at 12:31
Sort of. All materials get removed from the data-block by removing all material slots as well. Afterwards the materials do still exist, but they are no longer linked to the object. Unfortunately the Blender API is not very specific here. – Febulix Jun 15 '22 at 15:24
Wonder if calling object.data.materials.clear() then calling object.material_slot_remove_unused() is a safe idea - if it works, could be a better solution I guess – jupiterbjy May 28 '23 at 21:28

Removing all material slots in one go

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