Arc Length Problem

[debenriver]

Hi Eric.

Problem!

I draw a Line AB. I duplicate it. I rotate the duplicated line -30º from Point A, so that I now have a line AC.

I draw an arc centered on Point A, from Point B to Point C (using snap).

In the Edit pane the arc BC shows L = 0.

If I draw an arc, centered on Point A but not snapping to Point B and Point C, L = the length around the perimeter

If I pull a parallel from my original arc BC, the new arc also shows L = 0

If I draw an arc randomly L = the length around the perimeter

So, what's so special about my arc BC that the perimeter length can't be shown?

Cheers -- George

Example:

Arc.jpg (68.16 KiB) Viewed 18 times

The Red arc is pulled as a parallel from arc BC and also shows L = 0

The Green arc is drawn from Point A, but doesn't snap to B or C and shows L = 314.6652 which is correct.

[Eric Pousse]

Bonjour George,

Thank you very much to report this bug.
It is probably an old bug introduced when I added the arcs of ellipse.
L is not calculated when the start angle (SA) = 0.
You can turn around, by fixing SA to 0.00001 for example.
Or I can upload a beta version with the fix.

Cordialement.

[debenriver]

Right! Changing SA to 0.00001 worked!

So did drawing the air from Point A, snap to C and then snap to B, because SA was then 30º

Knowing the cause makes it easy to fix it on a drawing to drawing basis. And I guess wanting to know perimeter length of an arc is not particularly common! In fact this was the first time I needed to establish it!

If you issue a new version (6.0?), then it would be good to include a fix.

Thanks; Cheers -- George