origin property changes without any rotation/translation when difference() is applied.

[willywong]

Describe the bug
.origin property changes without any rotation/translation when difference() is applied.

However, if I assign an identity matrix explicitly as a separate handle, it performs the expected behavior (that is, the handle stays as identity matrix when no rotation/translation is applied to the solid).

To Reproduce
Run the following code and observe the stdout prints.

from openscad import *
import copy

# Clone a identity matrix constant.
IDENT = copy.deepcopy(cube(1).origin)

c = cube([3, 3, 3])

# This is identity matrix.
print(f"{c.origin=}")

c.artificial_origin = IDENT

# This is also an identity matrix
print(f"{c.artificial_origin=}")

# Engraving + align it to a face on X-Z plane.
txt = text('oops', halign='center', valign='center', size=0.5).linear_extrude(1).rotx(90).up(1).right(2)

# Apply the engraving
c -= txt

# c.origin is no longer the identity matrix.
print(f"Unexpected behavior. No longer same as identity matrix {c.origin=}")
print(f"Expected behavior. Still the same as identity matrix {c.artificial_origin=}")

res = [c]
show(res)

stdout:

c.origin=[[1.0, 0.0, 0.0, 0.0], [0.0, 1.0, 0.0, 0.0], [0.0, 0.0, 1.0, 0.0], [0.0, 0.0, 0.0, 1.0]]
c.artificial_origin=[[1.0, 0.0, 0.0, 0.0], [0.0, 1.0, 0.0, 0.0], [0.0, 0.0, 1.0, 0.0], [0.0, 0.0, 0.0, 1.0]]
Unexpected behavior. No longer same as identity matrix c.origin=[[1.0, 0.0, 0.0, 2.0], [0.0, 0.0, -1.0, 0.0], [0.0, 1.0, 0.0, 1.0], [0.0, 0.0, 0.0, 1.0]]
Expected behavior. Still the same as identity matrix c.artificial_origin=[[1.0, 0.0, 0.0, 0.0], [0.0, 1.0, 0.0, 0.0], [0.0, 0.0, 1.0, 0.0], [0.0, 0.0, 0.0, 1.0]]

Expected behavior
I would expect c.origin to behave exactly the same as c.artificial_origin. The only operation applied to the solid was difference(), which should not change the 4x4 matrix.

Code reproducing the issue
See above.

Screenshots

Environment and Version info (please complete the following information):

• OS: Windows 10
• System: Intel PC 64-bit
• OpenSCAD Version: OpenSCAD 2025.01.02, from pythonscad.org

Library & Graphics card information

OpenSCAD Version: 2025.01.02 (git )
System information: Microsoft Windows 10 (10.0.19045) x86_64 4 CPUs 15.97 GB RAM
User Agent: OpenSCAD/2025.01.02 (git ) (Microsoft Windows 10 (10.0.19045) x86_64)
Compiler: GCC "11.4.0" 64bit
MinGW build: MingW64
Debug build: No
Boost version: 1_81
Eigen version: 3.4.0
CGAL version, kernels: 5.5, Cartesian<Gmpq>, Extended_cartesian<Gmpq>, Epeck
OpenCSG version: OpenCSG 1.5.0
Manifold version: 3.0.1
Qt version: 5.15.11
QScintilla version: 2.11.2
InputDrivers: 
GLib version: 2.70.2
lodepng version: 20230410
libzip version: 1.5.2
fontconfig version: 2.14.2
freetype version: 2.13.2
harfbuzz version: 7.3.0
cairo version: 1.16.0
lib3mf version: 1.8.1
Features: roof, input-driver-dbus, lazy-union*, vertex-object-renderers-indexing*, textmetrics, import-function, predictible-output*
Application Path: C:/Program Files/PythonSCAD/bin
Documents Path: C:\Users\wiw\Documents
User Documents Path: C:\Users\wiw\Documents
Resource Path: C:/Program Files/PythonSCAD
User Library Path: C:/Users/wiw/Documents/OpenSCAD/libraries
User Config Path: C:\Users\wiw\AppData\Local/OpenSCAD
Backup Path: C:/Users/wiw/Documents/OpenSCAD/backups
OPENSCADPATH: <not set>
OpenSCAD library path:
C:/Users/wiw/Documents/OpenSCAD/libraries
C:/Program Files/PythonSCAD\libraries

OPENSCAD_FONT_PATH: <not set>
OpenSCAD font path:
C:/WINDOWS/fonts
C:/Users/wiw/AppData/Local/Microsoft/Windows/Fonts
C:/Users/wiw/.local/share/fonts
C:/usr/local/share/fonts
C:/usr/share/fonts
C:/usr/X11/lib/X11/fonts
C:/System/Library/Fonts
C:/Library/Fonts
C:/Users/wiw/Library/Fonts
GLEW version: 2.1.0
OpenGL Version: 4.6.0 Compatibility Profile Context 24.9.1.240813
GL Renderer: Radeon (TM) RX 480 Graphics
GL Vendor: ATI Technologies Inc.
RGBA(8888), depth(32), stencil(8)
GL_ARB_framebuffer_object: yes
GL_EXT_framebuffer_object: yes
GL_EXT_packed_depth_stencil: yes

Qt graphics widget: QOpenGLWidget
QSurfaceFormat: RGBA(8888), depth(32), stencil(8)

GL Extensions:
GL_AMD_blend_minmax_factor
GL_AMD_conservative_depth
GL_AMD_depth_clamp_separate
GL_AMD_gpu_shader_half_float
GL_AMD_gpu_shader_int16
GL_AMD_gpu_shader_int64
GL_AMD_multi_draw_indirect
GL_AMD_pinned_memory
GL_AMD_query_buffer_object
GL_AMD_sample_positions
GL_AMD_seamless_cubemap_per_texture
GL_AMD_shader_trinary_minmax
GL_AMD_texture_cube_map_array
GL_AMD_vertex_shader_layer
GL_AMD_vertex_shader_viewport_index
GL_ARB_ES2_compatibility
GL_ARB_ES3_compatibility
GL_ARB_arrays_of_arrays
GL_ARB_base_instance
GL_ARB_bindless_texture
GL_ARB_blend_func_extended
GL_ARB_buffer_storage
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GL_ARB_clip_control
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GL_ARB_compatibility
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GL_ARB_copy_buffer
GL_ARB_copy_image
GL_ARB_cull_distance
GL_ARB_debug_output
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GL_ARB_depth_clamp
GL_ARB_depth_texture
GL_ARB_derivative_control
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GL_ARB_point_parameters
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GL_ARB_program_interface_query
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GL_EXT_texture_env_add
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GL_EXT_texture_env_dot3
GL_EXT_texture_filter_anisotropic
GL_EXT_texture_integer
GL_EXT_texture_lod
GL_EXT_texture_lod_bias
GL_EXT_texture_mirror_clamp
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GL_SUN_multi_draw_arrays
WGL_EXT_swap_control

[pythonscad]

THANK you for your extensive bug report.
origin was overwritten by the origin of "txt" which was different.

Generally I am not clear, how to copy the handles of both operands onto the result.
right now i only copy the argument of the left hand operand.

its fixed. thank you for pointing out