Unexpected Brep trimming behavior

[chenkasirer]

When trimming Brep using brep.trimmed() getting an unexpected result compared to Rhino. Specifically, the portion of the brep that is cut away is the one at the opposite direction of the plane's normal. In Rhino, the portion at the direction of the normal is cut.

To Reproduce

  from compas.geometry import Box, Line, Plane, Brep, Point, Vector
  brep = Brep.from_box(Box(xsize=2, ysize=0.1, zsize=0.2))
  plane = Plane(point=Point(x=0.5, y=0.0, z=0.0), normal=Vector(x=0.923, y=-0.382, z=0.0) * -1.0)
  result = brep.trimmed(plane)

  viewer = Viewer(rendermode="ghosted")
  # viewer.add(brep)
  viewer.add(result)
  viewer.add(plane)
  viewer.add(Line(plane.point, plane.point + plane.normal))
  viewer.show()

Expected behavior

I would expect the the portion trimmed away is always where the plane's normal is pointing and documented it accordingly in the RhinoBrep implementation.

However, if this is not the desired maybe we can discuss and agree on a consistent convention?

Screenshots

Desktop (please complete the following information):

• compas_occ==1.01
• OS: Windows
• Python 3.12
• Conda

[chenkasirer]

I think this should be the opposite:

compas_occ/src/compas_occ/brep/brep.py

Lines 1451 to 1453 in d310651

	if is_point_infrontof_plane(point, plane):
	occ_shape = test
	break

as it was before:
e3ee66c

[tomvanmele]

should be solved now. will release new version soon...