wrong y size of `ngon`

[abraunst]

I found out that the y dimension of polygons produced with ngon is wrong.

For instance

compose(context(units=UnitBox(-3,-3,6,6)), ngon(0, 0, 1, 6), rectangle(-cos(π/6),-√2,2cos(π/6),2√2), stroke("red")) |> SVG("save.png")

Produces

which means that the y dimension is 2√2 instead of being twice the radius, i.e. 2

[Mattriks]

The idea here was that the ngon appears visually round in any context. Yes it's arbitrary whether the radius size is hooked to the x or y-axis (but not both). A common use case is in plotting, where point size is mapped to a third variable (not x or y). Another example is:

gridf(xs, ys, args...) = (context(),
   line([[(x, 0h), (x, 1h)] for x in xs]), line([[(0w, y), (1w, y)] for y in ys]), args..., linewidth(0.1mm))

p1 = compose(context(units=UnitBox(-3,-3,6,6)), ngon(0, 0, 1, 6), gridf(-3:3, -3:3, stroke("gray")))
draw(SVG(5inch, 3.3inch), p1)

See #409 for some history behind Compose size units.

[abraunst]

Thank you for the explanation! I'll close the issue and PR.

Shouldn't something be added to the docstring of ngon ?

Define a n-sided polygon with its center at (x,y), and radius of r

seems misleading to me.