Example on how to recursively check material expressions

sample_material_expressions.py

""" Run recursively through material expressions in Unreal Engine """

import unreal
from typing import *

# ---- ENTER A VALID PACKAGE NAME HERE TO RUN THE SCRIPT
PACKAGE_NAME = "/Game/Developers/..."
if PACKAGE_NAME == "/Game/Developers/...":
    unreal.log_error("Please change the package path to a valid material in the sample code!")

material = unreal.get_editor_subsystem(unreal.EditorAssetSubsystem).load_asset(PACKAGE_NAME)

unreal.log("{material}:".format(material=material.get_name()))
unreal.log("{underline}:".format(underline=len(material.get_name())*"="))

def get_material_expressions(material : unreal.Material, material_expression : unreal.MaterialExpression) -> List[unreal.MaterialExpression]:
    """
    Recursively get all material expressions connected to a given material expression
    
    :param material: material
    :param material expression: get all expressions connected to this expression

    :return: list of material expressions
    """
    if not material_expression:
        return []
    expressions = unreal.MaterialEditingLibrary.get_inputs_for_material_expression(material, material_expression)
    if len(list(filter(lambda e: e, expressions))) == 0:
        return expressions
    result = []
    for expression in expressions:
        _result = get_material_expressions(material, expression)
        if len(list(filter(lambda e: e != None, _result))) == 0:
            continue
        result.extend(_result)
    expressions.extend(result)
    return expressions

material_properties = {
    "ambient_occlusion": unreal.MaterialEditingLibrary.get_material_property_input_node(material, unreal.MaterialProperty.MP_AMBIENT_OCCLUSION),
    "base_color": unreal.MaterialEditingLibrary.get_material_property_input_node(material, unreal.MaterialProperty.MP_BASE_COLOR),
    "emissive": unreal.MaterialEditingLibrary.get_material_property_input_node(material, unreal.MaterialProperty.MP_EMISSIVE_COLOR),
    "metallic": unreal.MaterialEditingLibrary.get_material_property_input_node(material, unreal.MaterialProperty.MP_METALLIC),
    "normal": unreal.MaterialEditingLibrary.get_material_property_input_node(material, unreal.MaterialProperty.MP_NORMAL),
    "opacity": unreal.MaterialEditingLibrary.get_material_property_input_node(material, unreal.MaterialProperty.MP_OPACITY),
    "opacity_mask": unreal.MaterialEditingLibrary.get_material_property_input_node(material, unreal.MaterialProperty.MP_OPACITY_MASK),
    "refraction": unreal.MaterialEditingLibrary.get_material_property_input_node(material, unreal.MaterialProperty.MP_REFRACTION),
    "roughness": unreal.MaterialEditingLibrary.get_material_property_input_node(material, unreal.MaterialProperty.MP_ROUGHNESS),
    "specular": unreal.MaterialEditingLibrary.get_material_property_input_node(material, unreal.MaterialProperty.MP_SPECULAR),
    "sss_color": unreal.MaterialEditingLibrary.get_material_property_input_node(material, unreal.MaterialProperty.MP_SUBSURFACE_COLOR)
}
all_material_expressions = []  # list to store all material expressions in a given material

for name, expression in material_properties.items():
    if not expression:
        # material propery is not connected to any material expression
        continue
    material_expressions = get_material_expressions(material, expression)
    all_material_expressions.extend(material_expressions)
    all_material_expressions.append(expression)
    
for expression in all_material_expressions:
    # handle expression that directly connect to material properties
    if isinstance(expression, unreal.MaterialExpressionMaterialFunctionCall):
        print("{material} >> {expression} <Material Function Call>".format(material=material.get_name(), expression=expression.get_name()))
    if isinstance(expression, unreal.MaterialExpressionNamedRerouteUsage):
        print("{material} >> {expression} <Named Reroute Usage>".format(material=material.get_name(), expression=expression.get_name()))