Part Wire needs a specific ordering to reconstruct wire using deserialise_shape

[OceanNuclear]

Expected behaviour

Start point == start point of the first edge,
end point == end point of the last edge.
i.e.
BluemiraWire.start_point() == BluemiraWire.edges[0].start_point()
BluemiraWire.end_point() == BluemiraWire.edges[-1].end_point

Actual behaviour

Start point == start point of the LAST edge,
end point == end point of the FIRST edge.
i.e.
BluemiraWire.start_point() == BluemiraWire.edges[0].start_point()
BluemiraWire.end_point() == BluemiraWire.edges[-1].end_point

Example/Steps to reproduce

Loading the divertor face wire to examine.

Screenshots / Tracebacks

Explanation

This is because BluemiraWire.shape.Edges is sorted in reverse order, for reasons unclear to me.

Proposed solution

In _freecadapi::start_point and _freecadapi::end_point, Wrap the obj.Edges inside the Part.sortEdges function (and then unpack by indexing to [0]), before indexing to [0] and [-1] as before, respectively.

Note

I guess this means freecad's API uses memory in a weird/unpythonic way where lists are not ordered by default?

[OceanNuclear]

This underlying issue seems to also plague BluemiraWire.value_at. It's worth looking into the example file I've provided.

Or it could be an issue with deserialize_shape/serialize_shape.

[je-cook]

There is also shape.OrderedEdges. either way on the whole you shouldn't have to use any freecad api to do this

[je-cook]

I would also wager it may come from deserialising the wire

[je-cook]

After looking into this it seems like all the edges are reconstructed correctly by the deserialiser but when combined the shape created is not as expected. This could be down to a number of things but my guess is that it may be effected by #1347 and will be very hard to isolate until that is closed.

For now there is nothing particular that can be done to improve the situation other than to note that serialise_shape and deserialise_shape should be used with caution. The serialiser seems to produce what its expected however