How to replace materials in one blender file with materials of the same names from another file without creating copies

Question

I have two blender files that have different materials with the same names.

Both were originally in Blender Internal, but I manually converted the BI materials to eevee in one of them.

The other file, which has a lot of materials with the same exact names as in the other, does not have the updated versions yet, and I'd like to easily swap them out for the ones I manually converted.

I have almost 600 materials in the first file that may need to replace the old ones in the second file, so if I can avoid having to go through each one, that would be awesome.

Markus von Broady · Accepted Answer · 2021-07-10T14:49:30.633

Python script

Change the path on line 3 src_file = "E:/tempmymat.blend"

import bpy
src_file = "E:/tempmymat.blend"
D = bpy.data
def main():
    # find materials that you want to replace
    bad_mats = {m.name:m for m in D.materials if not m.library}
# load materials to replace with
with D.libraries.load(src_file, link=True) as (src, me):
    me.materials = [name for name in src.materials if name in bad_mats]

# create copies of the loaded file's materials, rename them and store
# a convenient dictionary pointing from old materials to new materials
replacements = {}
for m in me.materials:
    new_mat = m.copy()
    bad_mat = bad_mats[m.name]
    new_mat.name = m.name
    replacements[bad_mat] = new_mat

# find old materials and replace with new materials
for o in D.objects:
    for slot in o.material_slots:
        replacement = replacements.get(slot.material)
        if replacement:
            slot.material = replacement

# unlink old materials and the external file (library)
for m in bad_mats.values():
    D.materials.remove(m)
D.libraries.remove(D.libraries[-1])



main()

if not m.library is used on the first line of main() in order to ensure there's a single material with each name. If you need to make it work with materials linked to other files also being replaced, remove that condition. If you're worried that as a result you can indeed get multiple materials with the same name in that dictionary, you need to come up with some other method of associating a loaded material with an existing material.

How can I replace a material from Python?

How to Link/Append a data-block using the Python API?

Thanks for the great answer, Markus. It was a good head start into scripting Blender for me. Unfortunately, your script does not do deep copies of materials. That means that image texture for example get lost when unlinking the source file. Is there an easy way to copy all dependencies of material nodes? — Jan Bernhardt, Nov 03 '22 at 18:00

How to replace materials in one blender file with materials of the same names from another file without creating copies

1 Answers1

Python script