New free functions for arcs?

[DavidMStraub]

When using the free function API, a circular arc can be created in one of the following ways:

import cadquery as cq
import cadquery.func as cf

# 1. trim a full circle in parameter space (radians)
a1 = cf.circle(10).trim(0, pi / 2)

# 2. fall back to the Edge classmethods
a2 = cq.Edge.makeThreePointArc((10, 0, 0), (7.07, 7.07, 0), (0, 10, 0))
a3 = cq.Edge.makeCircle(10, angle1=0, angle2=90)

Both work well, and it's nice that the classmethods slot straight into the free function workflow.

Still, I think arcs are common enough that dedicated free functions would make cadquery.func even more pleasant to use, and easier to discover for newcomers (students!). The same goes for a few other curve constructors that are currently only available as Edge/Wire classmethods: tangent arc, partial ellipse, Bezier and helix.

Something along these lines, perhaps:

cf.arc(p1, p2, p3)       # three-point arc
cf.arc(p1, p2, t=t)      # tangent arc
cf.arc(r, a1, a2)        # arc at the origin in XY
cf.bezier(*pts)
cf.helix(pitch, h, d)

These could be thin @multimethod wrappers around the existing classmethods, in the same style as spline and text. @adam-urbanczyk what do you think? I'd be happy to open a PR.

[adam-urbanczyk]

Sounds good, PR would be nice.

[lorenzncode]

As a workaround I've used Sketch arc in some cases. From #1885:

path1 = Sketch().arc((0, 0), x1, 0, 180).val().move(rx=90, z=h)