Add polarLine and polarLineTo methods

[johnbeard]

Useful for defining lines when you know the length and angle, rather than the Cartesian co-ordinates.

Based on issue #291

[coveralls]

Coverage increased (+0.03%) to 92.28% when pulling 7a3a56132e777dfe4fe1c23b7b2562cc82d77f0a on johnbeard:polarline into 6251ec08366efebe64f8e73a424d174b414e17f9 on dcowden:master.

[AppVeyorBot]

:white_check_mark: Build cadquery 1.0.73 completed (commit https://github.com/dcowden/cadquery/commit/9b4ee30572 by @johnbeard)

[codecov-io]

Codecov Report

Merging #292 into master will increase coverage by 0.02%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #292      +/-   ##
==========================================
+ Coverage   92.79%   92.82%   +0.02%     
==========================================
  Files          10       10              
  Lines        2207     2215       +8     
==========================================
+ Hits         2048     2056       +8     
  Misses        159      159

Impacted Files	Coverage Δ
cadquery/cq.py	94.33% <100%> (+0.06%)	:arrow_up:

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[johnbeard]

Something else which occurred to me is would it be useful to have polarLineToX and polarLineToY functions, which extend a line at a given angle from the current point to the given ordinate/mantissa? For example, go from here at an angle of 30 degrees until you hit x=40. It would make things like set-backs quite straightforward.

The questions then would be:

• What happens when the line will never meet (e.g. from (0,0), vertical line until x = 10)?
• What happens when the angle goes away from the target (e.g. from (0,0), 45 degrees until x = -10)? Could choose to shoot the line the other way (i.e. add 180 degrees) or error?

[dcowden]

@johnbeard thanks for the contribution!

This looks great to me. Would you like to merge it as is, or do you want to also add the other versions you are contemplating above first?

[johnbeard]

I don't really mind, it can a follow-up PR if you want.

I would like to know what you'd like to do on error (e.g. parallel line) or a "reverse" situation before I do the toX and toY variants (and only if you agree they are desirable).

[johnbeard]

Hmm, looking at it, the neatest way to do toX and toY probably would be using Vector.projectToLine somehow. I'd rather not do too much vector maths when we have a full-scale geometry kernel to do it for us.

Perhaps just merge this and I'll have a think about the other methods.

[dcowden]

@johnbeard i tend to agree that proceeding as-is is best. I think polarLineToX and polarLineToY would be rarely used. and then the error cases you'd be describing would be rare within those cases.

Unrelated, i think what would be really cool is ability to draw lines and have them trimmed when they intersect others. that's a baby version of constrtraint solving.

What I really want is a 2d sketch solver, so that instead of doing the math on a piece of paper, you can actually create the sketch the same way you would in Solidworks or FreeCAD -- in which you link the geometry to contraints and let it solve.

[jmwright]

@johnbeard @dcowden It sounds like this is ready to merge. Is that correct?

[dcowden]

I think so

[jmwright]

Thanks for the contribution @johnbeard