Radius selector

[marcus7070]

Will close #501.

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I've added an Edge.radius method to get the radius of a circular edge.

The method uses _geomAdaptor().Circle(). When I used that code on a elipse, I got the kernel (7.4.0) to segfault. So I've restricted the method to just objects with geomType() == "CIRCLE" to be safe.

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I've added a RadiusSelector in the style of DirectionNthSelector.

I didn't add RadiusSelector to the string selector interface.

While I added it to the HTML docs, about half the selectors are not in the top level module and they don't show up due to #493.

[jmwright]

Thanks for working on this @marcus7070

@adam-urbanczyk The errors with Travis, Appveyor and the doc builds seem to be related to font/text capability. Items like this:

ImportError: cannot import name 'Font_BRepTextBuilder'

Did something change with the deployed versions of OCP? Maybe related to the 7.5 beta?

[adam-urbanczyk]

Indeed @jmwright , should be fine now.

[codecov]

Codecov Report

Merging #504 (821886f) into master (28d6089) will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #504      +/-   ##
==========================================
+ Coverage   93.74%   93.81%   +0.07%     
==========================================
  Files          30       30              
  Lines        5994     6067      +73     
  Branches      636      637       +1     
==========================================
+ Hits         5619     5692      +73     
  Misses        237      237              
  Partials      138      138              

Impacted Files	Coverage Δ
cadquery/occ_impl/shapes.py	91.30% <100.00%> (+0.07%)	⬆️
cadquery/selectors.py	99.17% <100.00%> (+0.07%)	⬆️
tests/test_cad_objects.py	99.10% <100.00%> (+0.11%)	⬆️
tests/test_selectors.py	100.00% <100.00%> (ø)

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[jmwright]

All green now.

@marcus7070 I'm assuming this is ready for review now?

[marcus7070]

Yes, ready for review @jmwright.

[marcus7070]

So I think when you request the radius of a Wire with multiple Edges, OCCT just takes the radius of the first Edge and calls it a day. You can see code regarding this in test_cad_objects.py. This was pretty unexpected for me, so I've mentioned it in the radius docstring.

It wouldn't be too hard to do some more logic in the radius method. We could grab the radius of every edge in a wire, and if they are all within a tolerance return the average value as the radius, otherwise raise ValueError. But I've stuck with the OCCT logic for now. Let me know if you have opinions either way.

[adam-urbanczyk]

Thanks, looks good!

[adam-urbanczyk]

@jmwright are OK with merging this PR?

[jmwright]

Thanks @marcus7070 ! This is a great addition to the selectors.