Blender - Bulk change OpenGL to DirectX

"""Convert OpenGL normal-map nodes to DirectX normal-map nodes in this scene.

Run this script from Blender's Text Editor. It updates every Normal Map node in
materials assigned to objects in the active scene, including nodes inside nested
shader node groups.
"""

import bpy


def iter_material_node_trees(material):
    """Yield the material node tree and any nested shader node-group trees once."""
    visited_trees = set()

    def visit(node_tree):
        if node_tree is None or node_tree.as_pointer() in visited_trees:
            return

        visited_trees.add(node_tree.as_pointer())
        yield node_tree

        for node in node_tree.nodes:
            if node.type == 'GROUP' and node.node_tree is not None:
                yield from visit(node.node_tree)

    yield from visit(material.node_tree)


def scene_materials(scene):
    """Yield each material assigned to an object in *scene* once."""
    seen_materials = set()

    for obj in scene.objects:
        for material_slot in obj.material_slots:
            material = material_slot.material
            if material is None or material.as_pointer() in seen_materials:
                continue

            seen_materials.add(material.as_pointer())
            yield material


def convert_opengl_normal_maps_to_directx(scene=None):
    """Set OpenGL Normal Map node conventions to DirectX and return counts."""
    scene = scene or bpy.context.scene
    material_count = 0
    converted_count = 0

    for material in scene_materials(scene):
        if not material.use_nodes or material.node_tree is None:
            continue

        material_count += 1
        for node_tree in iter_material_node_trees(material):
            for node in node_tree.nodes:
                if node.type != 'NORMAL_MAP':
                    continue

                # Blender 5.2's Normal Map node Mode dropdown; this does not
                # modify the RGB values in the source image.
                if node.convention == 'OPENGL':
                    node.convention = 'DIRECTX'
                    converted_count += 1

    print(
        f"OpenGL to DirectX Normal Map: converted {converted_count} node(s) "
        f"across {material_count} scene material(s)."
    )
    return converted_count, material_count


if __name__ == "__main__":
    convert_opengl_normal_maps_to_directx()