__init__.py

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#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU General Public License
#  as published by the Free Software Foundation; either version 3
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bl_info = {
    "name": "Reset All Vector Normals on Selected Objects",
    "author": "Walter Palladino",
    "version": (0, 1, 0),
    "blender": (3, 0, 0),
    "location": "View3D > Object > Apply > Reset All Vector Normals",
    "description": "Reset All Vector Normals on Selected Objects",
    "warning": "",
    "doc_url": "https://github.com/walterpalladino/resetAllVectorNormals#readme",
    "category": "Object",
}


import bpy

context = bpy.context
data = bpy.data



def main(context):
    # Select only Meshes
    selected_objects = [obj  for obj in context.selected_objects if obj.type == 'MESH']

    # Iterate on all the meshes
    for obj in selected_objects:
        # set the object to active
        bpy.context.view_layer.objects.active = obj
        bpy.ops.object.mode_set(mode="EDIT")
        bpy.ops.mesh.select_mode(type="FACE")
        bpy.ops.mesh.select_all(action='SELECT')

        # recalculate outside normals 
        bpy.ops.mesh.normals_make_consistent(inside=False)
        bpy.ops.mesh.normals_tools(mode='RESET')

        bpy.ops.object.mode_set(mode="OBJECT")


class ResetAllVectorNormals(bpy.types.Operator):
    """Iterate on all selected objects, switch to edit mode, select faces and reset normal vectors"""
    bl_idname = "object.reset_all_vector_normals"
    bl_label = "Reset All Vector Normals"

    def execute(self, context):
        main(context)
        return {'FINISHED'}


def menu_func_setup(self, context):
    self.layout.operator(ResetAllVectorNormals.bl_idname, text=ResetAllVectorNormals.bl_label)


def register():
    bpy.utils.register_class(ResetAllVectorNormals)
    bpy.types.VIEW3D_MT_object_apply.append(menu_func_setup)


def unregister():
    bpy.utils.unregister_class(ResetAllVectorNormals)
    bpy.types.VIEW3D_MT_object_apply.remove(menu_func_setup)


if __name__ == "__main__":
    register()