utils.py

import bpy
import os
import sys
import math
import random
import numpy as np

# random material
def get_random_color():
    ''' generate rgb using a list comprehension '''
    r, g, b = [random.random() for i in range(3)]
    return r, g, b, 1


# rotation
def rotate(point, angle_degrees, axis=(0,1,0)):
    theta_degrees = angle_degrees
    theta_radians = math.radians(theta_degrees)

    rotated_point =  np.dot(rotation_matrix(axis, theta_radians), point)
    
    return rotated_point


def rotation_matrix(axis, theta):
    """
    Return the rotation matrix associated with counterclockwise rotation about
    the given axis by theta radians.
    """
    axis = np.asarray(axis)
    axis = axis / math.sqrt(np.dot(axis, axis))
    a = math.cos(theta / 2.0)
    b, c, d = -axis * math.sin(theta / 2.0)
    aa, bb, cc, dd = a * a, b * b, c * c, d * d
    bc, ad, ac, ab, bd, cd = b * c, a * d, a * c, a * b, b * d, c * d
    return np.array([[aa + bb - cc - dd, 2 * (bc + ad), 2 * (bd - ac)],
                     [2 * (bc - ad), aa + cc - bb - dd, 2 * (cd + ab)],
                     [2 * (bd + ac), 2 * (cd - ab), aa + dd - bb - cc]])