Example for using a lambda inside ShapeList.filter_by

[CarpeNecopinum]

Question that came up in the Discord server was how to filter faces by being parallel to a given axis, as there is no built-in filter for it:

part.faces().filter_by(lambda f: abs(f.normal_at(None).dot(axis)) < 1e-6)

Jern noted that there are no examples showing this feature (lambda as filter), so we should probably add one / a few.

[jdegenstein]

Thank you! Would be good to add this to page https://build123d.readthedocs.io/en/latest/key_concepts.html#custom-sorting-and-filtering

[gumyr]

shape = Box(1, 1, 1)
f_parallel = shape.faces().filter_by(lambda f: abs(f.normal_at().dot(Axis.X.direction)) < 1e-6)
f_perpendicular = shape.faces().filter_by(Axis.X)

Might want to clarify that the dot method expects a Vector and not an Axis.