transform_cube_by_ucs.py

# Copyright (c) 2020-2022 Manfred Moitzi
# License: MIT License
import pathlib

import math
import ezdxf
from ezdxf import zoom
from ezdxf.math import UCS

CWD = pathlib.Path("~/Desktop/Outbox").expanduser()
if not CWD.exists():
    CWD = pathlib.Path(".")


# ------------------------------------------------------------------------------
# use an UCS to place a cube in 3D
#
# docs: https://ezdxf.mozman.at/docs/math/core.html#ucs-class
# tutorial for UCS based transformations: https://ezdxf.mozman.at/docs/tutorials/ucs_transform.html
#
# IMPORTANT: the ezdxf.math.UCS is not identical to the UCSTableEntry in
# the TABLE section, but you can acquire the USC by UCSTableEntry.ucs():
# https://ezdxf.mozman.at/docs/tables/ucs_table_entry.html#ezdxf.entities.UCSTableEntry.ucs
# ------------------------------------------------------------------------------

p = [
    (0, 0, 0),
    (1, 0, 0),
    (1, 1, 0),
    (0, 1, 0),
    (0, 0, 1),
    (1, 0, 1),
    (1, 1, 1),
    (0, 1, 1),
]

doc = ezdxf.new()
msp = doc.modelspace()
block = doc.blocks.new("block_4m3")

cube = block.add_mesh()
with cube.edit_data() as mesh_data:
    mesh_data.add_face([p[0], p[1], p[2], p[3]])
    mesh_data.add_face([p[4], p[5], p[6], p[7]])
    mesh_data.add_face([p[0], p[1], p[5], p[4]])
    mesh_data.add_face([p[1], p[2], p[6], p[5]])
    mesh_data.add_face([p[3], p[2], p[6], p[7]])
    mesh_data.add_face([p[0], p[3], p[7], p[4]])
    mesh_data.optimize()


# Place untransformed cube, don't use the rotation
# attribute unless you really need it, just
# transform the UCS.
blockref = msp.add_blockref(name="block_4m3", insert=(0, 0, 0))

# First rotation about the local x-axis
ucs = UCS().rotate_local_x(angle=math.radians(45))
# same as a rotation around the WCS x-axis:
# ucs = UCS().rotate(axis=(1, 0, 0), angle=math.radians(45))

# Second rotation about the WCS z-axis
ucs = ucs.rotate(axis=(0, 0, 1), angle=math.radians(45))

# Last step transform block reference from UCS to WCS
blockref.transform(ucs.matrix)

zoom.extents(msp)
doc.saveas(CWD / "cube.dxf")