More shape/free func improvements

[adam-urbanczyk]

• normalAt for surfaces
• bad fonts workaround (fuse)
• loft to/from vertex
• edge/face trim
• more loft options
  • parametrization
  • continuity
• shell construction fix
• aux spine for sweep
• params for spline
• cq.vis.show extensions
• tests

---

cq.vis.show demo:

show(
   sphere(1),
    circle(1).moved(rx=90).positions(linspace(0,1)),
    circle(1).locations(linspace(0,1)),
    Location(),
    circle(1),
    plane(0.5,0.5),
    scale=0.2,
    alpha=0.5
)

[adam-urbanczyk]

A lot of small, mostly advanced, but very useful stuff. show extensions is by far most relevant for typical user + some extensions of the free func api (more complete spline and loft options).

[lorenzncode]

Is this trim result correct?

pts = [
    (0, 0),
    (1, 0),
    (0, 1),
]

f1 = face(polygon(*pts))
f2 = f1.trim(0, 0.5, 0, 1)
print(f2.Area())  # this returns 0.5; I was expecting 0.375 which is the area of f1 * f2 here?

[jmwright]

Suggested change

	# used to check is building inner parts makes sense
	# used to check if building inner parts makes sense

[jmwright]

Thanks @adam-urbanczyk !

[adam-urbanczyk]

Is this trim result correct?

pts = [
    (0, 0),
    (1, 0),
    (0, 1),
]

f1 = face(polygon(*pts))
f2 = f1.trim(0, 0.5, 0, 1)
print(f2.Area())  # this returns 0.5; I was expecting 0.375 which is the area of f1 * f2 here?

It is, trim trims the base geometry.

I added a small clarification in the docstrings.

[adam-urbanczyk]

@lorenzncode I think everything is fixed, anything against merging?

[lorenzncode]

Thanks @adam-urbanczyk! Yes please go ahead. Do you want to link the font issue with this PR? #1639 can be closed with this too.