Boost logo

Geometry :

Subject: [ggl] Touching polygons and floating-point
From: Barend Gehrels (barend)
Date: 2011-02-11 05:40:19

Op 11-2-2011 11:19, Denis Pesotsky schreef:
> Thanks for answer. But I mean a bit other thing. You noticied same
> thing in your blog ("Precision, the cause of spikes").
> For example, 1st polygon have coordinates like (1, 1) and (4, 2.3)
> (and 1 more coordinate somewhere) and other have coordinates like
> (2.1, y1) and (3, y2), where y1 is y coordinate for crosspoint of
> Line({1, 1} {4, 2.3}) and y=2.1, while y2 is y coordinate for
> cross-point of same line and y=3. In float-point presentation that
> points can be not exactly on this line, but very close. Can this
> result in leaving 2 separate polygons after union?
In this described case, probably not, using float or double. But it
might occur, yes. There is no fuzzy detection indeed. I'll come back to
this with some details.


Geometry list run by mateusz at