"3mf mesh is invalid" from imported SVG

[adamcrume]

Simply extruding one of the shapes from https://rustacean.net/assets/rustacean-flat-noshadow.svg and meshing it raises an error.

from build123d import Mesher, extrude, import_svg

shapes = import_svg("rustacean-flat-noshadow.svg")
Mesher().add_shape(extrude(shapes[3], 1))

Traceback (most recent call last):
  File "/home/adam/Documents/3d-printing/badge flair build123d/src/bug.py", line 16, in <module>
    Mesher().add_shape(extrude(shapes[3], 1))
  File "/home/adam/apps/build123d/lib/python3.12/site-packages/build123d/mesher.py", line 442, in add_shape
    raise RuntimeError("3mf mesh is invalid")
RuntimeError: 3mf mesh is invalid

[snoyer]

shapes[3] comes from a self-intersecting path that would be a valid Wire but does not produce a valid Face

[w.is_valid() for w in shapes[3].wires()] = [True]
shapes[3].is_valid() = False

rustacean-flat-noshadow.mp4

[jdegenstein]

Related issue #842 with some discussion and advice

[adamcrume]

OH MY GOSH, no wonder I didn't see that, it's so tiny. Thanks! Is there a way to split apart the wire in code so that it would generate valid faces (i.e. if I want this to work for other SVGs)? #842 doesn't have much detail.

[gumyr]

Yes, both Edge or Wire have trim methods that can be used to shorten them but finding the right Edge/Wire and the right place and rebuilding the shape with the shorten shape look to be challenging.