Re: [Lib2geom-devel] tangent to curve

[Nathan H. <nj...@nj...>]

On Fri, Mar 27, 2015 at 01:36:14PM +0100, Tavmjong Bah wrote:
> 
> Hi,
> 
> It seems that the tangent at a beginning of a curve can flip sign with
> slight changes to the curve (as returned by unitTangentAt()). Is this a
> known problem? There is a comment that the tangent at the end of a line
> can be wrong but nothing to indicate that the tangent at the beginning
> can be wrong. This appears to be the cause of mis-drawn line joins.

I looked into this this morning, I couldn't see any obvious bugs, do
you have a unit test sized reproducing example?  The fact that it's at
the endpoints makes me suspect Piecewise rather than the differential
geometry part.

njh