Automatic material creation in Unreal Engine with Python

ByGatis Kurzemnieks 4 Comments

Potential task for automation is creation of material instances for a lot of meshes. For example, I use Houdini to generate a lot of assets procedurally – models with baked texture maps. Importing all these meshes, textures and creating material instances (based on common master material) and assigning respective textures for each model is repetitive and boring manual task.

Here is a sample python script that is meant to run on selected static meshes – it will automatically create Material Instance asset for each mesh based on its name and assign all textures also based on name. At the end it assigns newly created material instance to the mesh.

It expects textures to be named the same as static meshes, but with appropriate postfixes – “_basecolor”, “_normal” etc. It also expects standard folder structure:

import unreal

def set_mi_texture(mi_asset, param_name, tex_path):
    if not unreal.EditorAssetLibrary.does_asset_exist(tex_path):
        unreal.log_warning("Can't find texture: " + tex_path)
        return False

    tex_asset = unreal.EditorAssetLibrary.find_asset_data( tex_path ).get_asset()
    return unreal.MaterialEditingLibrary.set_material_instance_texture_parameter_value(mi_asset, param_name, tex_asset)

unreal.log("---------------------------------------------------")

AssetTools = unreal.AssetToolsHelpers.get_asset_tools()
MaterialEditingLibrary = unreal.MaterialEditingLibrary
EditorAssetLibrary = unreal.EditorAssetLibrary

base_mtl = unreal.EditorAssetLibrary.find_asset_data("/Game/Environment/Cave/Materials/M_CaveBase")
    
#Iterate over selected meshes
sel_assets = unreal.EditorUtilityLibrary.get_selected_assets()

for sm_asset in sel_assets:
    if sm_asset.get_class().get_name() != "StaticMesh":
        continue #skip non-static-meshes
    
    asset_name = sm_asset.get_name()    
    if asset_name.startswith("S_"):
        asset_name = asset_name[2:] # Store mesh name without prefix

    asset_folder = unreal.Paths.get_path(sm_asset.get_path_name()) 

    base_folder = asset_folder[:-7] #get base folder (subtract "Meshes" from base path)
    mtl_folder = base_folder + "/Materials/"
    tex_folder = base_folder + "/Textures/"
    
    #create folder for materials if not exist
    if not unreal.EditorAssetLibrary.does_directory_exist(mtl_folder):
        unreal.EditorAssetLibrary.make_directory(mtl_folder)

    #name of material instance for this mesh
    mi_name = "MI_" + asset_name            
    mi_full_path = mtl_folder + mi_name

    #Check if material instance already exists
    if EditorAssetLibrary.does_asset_exist(mi_full_path):
        mi_asset = EditorAssetLibrary.find_asset_data(mi_full_path).get_asset()
        unreal.log("Asset already exists")
    else:
        mi_asset = AssetTools.create_asset(mi_name, mtl_folder, unreal.MaterialInstanceConstant, unreal.MaterialInstanceConstantFactoryNew())        

    #set material instance parameters!
    MaterialEditingLibrary.set_material_instance_parent( mi_asset, base_mtl.get_asset() )  # set parent material
    MaterialEditingLibrary.set_material_instance_scalar_parameter_value( mi_asset, "Desaturation", 0.3) # set scalar parameter 

    #find textures for this mesh
    set_mi_texture(mi_asset, "Base Color", tex_folder + "T_" + asset_name + "_basecolor")
    set_mi_texture(mi_asset, "Masks Map", tex_folder + "T_" + asset_name + "_masks")
    set_mi_texture(mi_asset, "Normal", tex_folder + "T_" + asset_name + "_normal")
    set_mi_texture(mi_asset, "BentNormal", tex_folder + "T_" + asset_name + "_Bentnormal")

    #set new material instance on static mesh    
    sm_asset.set_material(0, mi_asset)

This might not be useful as is, but could serve as a code example when trying to do similar things with assets in UE.

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About Gatis Kurzemnieks

Technical Artist

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