[geos-devel] Geometry/Rectangle Intersection: winding order

[Sandro Santilli]

On Mon, Sep 15, 2014 at 04:53:43PM +0200, Sandro Santilli wrote:
> On Mon, Sep 15, 2014 at 04:12:04PM +0200, Sandro Santilli wrote:
> > On Mon, Sep 15, 2014 at 03:16:16PM +0200, Sandro Santilli wrote:
> > 
> > > I wonder if the RectangleIntersection class should check winding order
> > > and reverse rings if needed...
> > 
> > I've added a check for winding order in the rectangle clipping code.
> > This adds one more full vertices scan for each hole. It doesn't look
> > like code winding order would affect the algorithm, am I right ?
> > 
> > See commit 4ae01eb0711baac11c102a847b90952619379b0d
> 
> I was wrong, it was easy to find a case of failure with counterclockwise
> shell. I'll add shell winding checking too. It'll add yet another full
> vertex scan for the exterior ring, further degrading performances ...

Mika, do you think RectangleIntersectionBuilder::reconnectPolygons could
accept an additional argument saying if the shell was CW or CCW ?
That way we could skip the additional full scan of the shell whenever
it is fully contained in the rectangle OR it fully contains it...

--strk;