On 20-6-2013 18:30, TONGARI wrote:
2013/6/21 Barend Gehrels <email@example.com>
No (about the last question).
On 20-6-2013 11:26, TONGARI wrote:
I'm not quite understand why we need traits::closure for
Ring & Polygon, aren't these always closed?
What should I expect if the closure is open? Should I see
Ring as Linestring then?
Apparently the doc about closure should be updated. However,
this page explains it clearly:
Yah, I somewhat missed that page, seems it does contain the
info I needed.
Since I'm writing my 2d graphics lib, I always think the
lib should close it anyway for drawing, but I don't know how
it matters in the context of geometry operations...
Sure, basically every algorithm needs polygons to be closed.
Therefore we have the closeable_view which closes them
automatically. Likewise we have the reversible_view which walks
through the points in opposite direction, if the rings are counter
clockwise. So basically (in a system where x is going up) we
consider, internally, with help of these two views, all polygons as
closed and clockwise.