blender-nurbspath-length.py

import bpy

def get_formatted_length_from_bu(length_in_blender_units):
    scene = bpy.context.scene
    unit_settings = scene.unit_settings

    if unit_settings.system == 'NONE':
        return f"{length_in_blender_units:.4f} Blender Units"

    system_conversions = {
        'METRIC': {
            'KILOMETERS': 0.001, 'METERS': 1.0, 'CENTIMETERS': 100.0,
            'MILLIMETERS': 1000.0, 'MICROMETERS': 1000000.0,
        },
        'IMPERIAL': {
            'MILES': 0.000621371, 'FEET': 3.28084,
            'INCHES': 39.3701, 'THOU': 39370.1,
        }
    }

    system_map = system_conversions.get(unit_settings.system)
    if not system_map:
        return f"{length_in_blender_units:.4f} Blender Units"

    conversion_factor = system_map.get(unit_settings.length_unit)
    if not conversion_factor:
        return f"{length_in_blender_units:.4f} Blender Units"

    scaled_length = length_in_blender_units * unit_settings.scale_length
    converted_length = scaled_length * conversion_factor
    
    unit_name = unit_settings.length_unit.replace('_', ' ').title()
    
    return f"{converted_length:.4f} {unit_name}"


def show_popup(message, title="", icon='INFO'):
    def draw(self, context):
        self.layout.label(text=message)
    bpy.context.window_manager.popup_menu(draw, title=title, icon=icon)


def show_curve_length():
    active_object = bpy.context.active_object

    if active_object and active_object.type == 'CURVE':
        total_length_bu = 0.0
        for spline in active_object.data.splines:
            total_length_bu += spline.calc_length()
        
        formatted_message = get_formatted_length_from_bu(total_length_bu)
        final_message = f"Length of '{active_object.name}': {formatted_message}"
        show_popup(message=final_message, title="Curve Length")
    else:
        error_message = "No active curve object selected. Please select a curve."
        show_popup(message=error_message, title="Error", icon='ERROR')

show_curve_length()