Strange behavior with edge order in face's wire

[geiseri]

I have a few issues in this file but first I need to clarify the order of Edges returned in a wire.

I am using a face in this test case to grab its outer wire so that I can use it in a future operation to create a sweep. The sweep has its own issues, but one big one comes from the fact it looks like the order of edges in the wire on line 20 seems to "shuffle" around. After 4 consecutive rounds running cq-server to build an STL I see the following output on line 25.

Run 1

edge 0 is [Vertex: (-10.0, -16.75, 2.629867970565564e-16), Vertex: (10.0, -16.75, 2.629867970565564e-16)]
edge 1 is [Vertex: (10.0, -16.75, 2.629867970565564e-16), Vertex: (11.75, -15.000000000000002, 2.629867970565564e-16)]
edge 2 is [Vertex: (11.75, 15.0, 2.629867970565564e-16), Vertex: (11.75, -15.000000000000002, 2.629867970565564e-16)]
edge 3 is [Vertex: (11.75, 15.0, 2.629867970565564e-16), Vertex: (10.0, 16.75, 2.629867970565564e-16)]
edge 4 is [Vertex: (-10.0, 16.75, 2.629867970565564e-16), Vertex: (10.0, 16.75, 2.629867970565564e-16)]
edge 5 is [Vertex: (-10.0, 16.75, 2.629867970565564e-16), Vertex: (-11.75, 15.000000000000002, 2.629867970565564e-16)]
edge 6 is [Vertex: (-11.75, 15.000000000000002, 2.629867970565564e-16), Vertex: (-11.75, -15.000000000000002, 2.629867970565564e-16)]
edge 7 is [Vertex: (-11.75, -15.000000000000002, 2.629867970565564e-16), Vertex: (-10.0, -16.75, 2.629867970565564e-16)]

Run 2

edge 0 is [Vertex: (11.75, 15.0, 8.76622656855189e-17), Vertex: (11.75, -15.000000000000002, 8.76622656855189e-17)]
edge 1 is [Vertex: (10.0, -16.75, 8.76622656855189e-17), Vertex: (11.75, -15.000000000000002, 8.76622656855189e-17)]
edge 2 is [Vertex: (-10.0, -16.75, 8.76622656855189e-17), Vertex: (10.0, -16.75, 8.76622656855189e-17)]
edge 3 is [Vertex: (-11.75, -15.000000000000002, 8.76622656855189e-17), Vertex: (-10.0, -16.75, 8.76622656855189e-17)]
edge 4 is [Vertex: (-11.75, 15.0, 8.76622656855189e-17), Vertex: (-11.75, -15.000000000000002, 8.76622656855189e-17)]
edge 5 is [Vertex: (-10.0, 16.75, 8.76622656855189e-17), Vertex: (-11.75, 15.0, 8.76622656855189e-17)]
edge 6 is [Vertex: (-10.0, 16.75, 8.76622656855189e-17), Vertex: (10.0, 16.75, 8.76622656855189e-17)]
edge 7 is [Vertex: (11.75, 15.0, 8.76622656855189e-17), Vertex: (10.0, 16.75, 8.76622656855189e-17)]

Run 3

edge 0 is [Vertex: (-10.0, 16.75, -3.5064906274207524e-16), Vertex: (10.0, 16.75, -3.5064906274207524e-16)]
edge 1 is [Vertex: (11.75, 15.000000000000002, -3.5064906274207524e-16), Vertex: (10.0, 16.75, -3.5064906274207524e-16)]
edge 2 is [Vertex: (11.75, 15.000000000000002, -3.5064906274207524e-16), Vertex: (11.75, -15.000000000000002, -3.5064906274207524e-16)]
edge 3 is [Vertex: (10.0, -16.75, -3.5064906274207524e-16), Vertex: (11.75, -15.000000000000002, -3.5064906274207524e-16)]
edge 4 is [Vertex: (-10.0, -16.75, -3.5064906274207524e-16), Vertex: (10.0, -16.75, -3.5064906274207524e-16)]
edge 5 is [Vertex: (-11.75, -15.000000000000002, -3.5064906274207524e-16), Vertex: (-10.0, -16.75, -3.5064906274207524e-16)]
edge 6 is [Vertex: (-11.75, 15.0, -3.5064906274207524e-16), Vertex: (-11.75, -15.000000000000002, -3.5064906274207524e-16)]
edge 7 is [Vertex: (-10.0, 16.75, -3.5064906274207524e-16), Vertex: (-11.75, 15.0, -3.5064906274207524e-16)]

Run 4

edge 0 is [Vertex: (11.75, 15.0, 7.012981254841505e-16), Vertex: (11.75, -15.000000000000002, 7.012981254841505e-16)]
edge 1 is [Vertex: (10.0, -16.75, 7.012981254841505e-16), Vertex: (11.75, -15.000000000000002, 7.012981254841505e-16)]
edge 2 is [Vertex: (-10.0, -16.75, 7.012981254841505e-16), Vertex: (10.0, -16.75, 7.012981254841505e-16)]
edge 3 is [Vertex: (-11.75, -15.000000000000002, 7.012981254841505e-16), Vertex: (-10.0, -16.75, 7.012981254841505e-16)]
edge 4 is [Vertex: (-11.75, 15.0, 7.012981254841505e-16), Vertex: (-11.75, -15.000000000000002, 7.012981254841505e-16)]
edge 5 is [Vertex: (-10.0, 16.75, 7.012981254841505e-16), Vertex: (-11.75, 15.0, 7.012981254841505e-16)]
edge 6 is [Vertex: (-10.0, 16.75, 7.012981254841505e-16), Vertex: (10.0, 16.75, 7.012981254841505e-16)]
edge 7 is [Vertex: (11.75, 15.0, 7.012981254841505e-16), Vertex: (10.0, 16.75, 7.012981254841505e-16)]

It looks like it comes back directly from the order of wires returned by the outerWire result on the face. It looks like this comes directly from here. Is this a bug? Is there maybe a better way to do this?

[adam-urbanczyk]

Iterators in OCCT (and thus in cq) are not ordered.

[geiseri]

Is there a way to provide a "start" and "end" vertex and have it sorted from there? I am not sure how you would sort them though. Where this trips me is when I intend to sweep along a wire, sometimes it seems to trip up.

[adam-urbanczyk]

CQ does not provide such functionality. You could sort them yourself, but I don't see why you'd need to specify order when sweeping.