blender_svd.py

# This example assumes we have a mesh object selected

import bpy
import bmesh
import numpy as np


obj = bpy.context.active_object
P = []
A = []
for v in obj.data.vertices: 
    co_final = obj.matrix_world @ v.co
    A.append([co_final.x,co_final.y,co_final.z])
    
A = np.array(A)
print (A.shape)
cenx = np.average(A[:,0])
ceny = np.average(A[:,1])
cenz = np.average(A[:,2])

A = []
for v in obj.data.vertices: 
    co_final = obj.matrix_world @ v.co
    A.append([co_final.x-cenx,co_final.y-ceny,co_final.z-cenz])
    
A = np.array(A)  
print ("centroid %f %f %f" % (cenx,ceny,cenz))
u,s,vh = np.linalg.svd(A, full_matrices=True)
np.set_printoptions(suppress=True)
print ("A=")
print (A)
print ("S=")
print (s)
    
print ("u=")
print (vh)


nn = obj.name+"_svd "
if nn in bpy.data.objects:
    empty = bpy.data.objects[nn]
else:
    print ("aa")
    empty = bpy.data.objects.new( nn, None )
    empty.empty_display_size = 10
    empty.empty_display_type = 'PLAIN_AXES'
    bpy.context.collection.objects.link(empty)
empty.matrix_world = ((vh[0,0],vh[0,1],vh[0,2],0),
                      (vh[1,0],vh[1,1],vh[1,2],0),
                      (vh[2,0],vh[2,1],vh[2,2],0),
                      (0,0,0,1))
empty.location.x = cenx
empty.location.y = ceny
empty.location.z = cenz

                                          
print ("Done")