Python - How to make box out of selected verts' bounding box in local space?

Question

I want to make a box out of selected verts' bounding box in local space

Answer 1

Draw oriented bounding box with GPU module

# suppose in edit mode

import bpy, gpu
import numpy as np
from mathutils import Vector
from gpu_extras.batch import batch_for_shader

def ret_obb(verts):
    points = np.asarray(verts)
    means = np.mean(points, axis=1)

    cov = np.cov(points, y = None,rowvar = 0,bias = 1)

    v, vect = np.linalg.eig(cov)

    tvect = np.transpose(vect)
    points_r = np.dot(points, np.linalg.inv(tvect))

    co_min = np.min(points_r, axis=0)
    co_max = np.max(points_r, axis=0)
    
    xmin, xmax = co_min[0], co_max[0]
    ymin, ymax = co_min[1], co_max[1]
    zmin, zmax = co_min[2], co_max[2]

    xdif = (xmax - xmin) * 0.5
    ydif = (ymax - ymin) * 0.5
    zdif = (zmax - zmin) * 0.5

    cx = xmin + xdif
    cy = ymin + ydif
    cz = zmin + zdif

    corners = np.array([
        [cx - xdif, cy - ydif, cz - zdif],
        [cx - xdif, cy + ydif, cz - zdif],
        [cx + xdif, cy + ydif, cz - zdif],
        [cx + xdif, cy - ydif, cz - zdif],
        [cx - xdif, cy - ydif, cz + zdif],
        [cx - xdif, cy + ydif, cz + zdif],
        [cx + xdif, cy + ydif, cz + zdif],
        [cx + xdif, cy - ydif, cz + zdif],
    ])

    corners = np.dot(corners, tvect)

    return [Vector((el[0], el[1], el[2])) for el in corners]


bpy.ops.object.mode_set(mode = 'OBJECT')
oj          = bpy.context.object
verts       = [v.co for v in oj.data.vertices if v.select]
obb_local   = ret_obb(verts)
mat         = oj.matrix_world
obb_world   = [mat @ v for v in obb_local]
bpy.ops.object.mode_set(mode = 'EDIT')

# draw with GPU Module
coords = [(v[0], v[1], v[2]) for v in obb_world]

indices = (
    (0, 1), (1, 2), (2, 3), (3, 0),
    (4, 5), (5, 6), (6, 7), (7, 4),
    (0, 4), (1, 5), (2, 6), (3, 7))

shader = gpu.shader.from_builtin('3D_UNIFORM_COLOR')
batch = batch_for_shader(shader, 'LINES', {"pos": coords}, indices=indices)


def draw():
    shader.bind()
    shader.uniform_float("color", (1, 0, 0, 1))
    batch.draw(shader)


bpy.types.SpaceView3D.draw_handler_add(draw, (), 'WINDOW', 'POST_VIEW')