Local Coordinates

Blocks to origin with flat face on bottom

import os
import json
from compas.geometry import subtract_vectors, cross_vectors
from compas.geometry import Frame, Transformation
from compas.datastructures import Mesh
from compas_rhino.artists import MeshArtist

HERE = os.path.dirname(__file__)
FILE_I = os.path.join(HERE, 'blocksflat.json')

with open(FILE_I, 'r') as f:
    blocks = [Mesh.from_data(data) for data in json.load(f)]

world = Frame.worldXY()

for block in blocks:
    point = block.face_centroid(1)
    normal = block.face_normal(1)
    vertices = block.face_vertices(1)
    xaxis = subtract_vectors(block.vertex_attributes(vertices[0], 'xyz'), point)
    yaxis = cross_vectors(xaxis, normal)
    local = Frame(point, xaxis, yaxis)
    X = Transformation.from_frame_to_frame(local, world)
    block.transform(X)

artist = MeshArtist(None, layer="RV2::BlocksTransformed")
artist.clear_layer()

for block in blocks:
    artist.mesh = block
    artist.draw_faces(color=(0, 255, 0), join_faces=True)

artist.redraw()