Polygon CCW winding check request

[Serge Monkewitz]

Hi Markus,

On Jun 13, 2018, at 3:04 PM, Markus Nullmeier <mnullmei at ari.uni-heidelberg.de> wrote:
> 
> Hello list,
> 
> On 13/06/18 20:19, Patrick Dowler wrote:
>> PPS-Anyone using postgresql+pgsphere should note that winding direction
>> doesn't matter for spoly because that library chose the "less than half the
>> sphere" definition
> 
> As one of pgSphere's maintainers, I consider this to be a bug
> in pgSphere from the beginning. The only remaining question is
> when/if I, or others, will find the time to fix it, or else
> somebody will find the money to directly order a fix.
> 
> Best regards,
> Markus Nullmeier


If you haven't already, I think it may be worth taking a look at the spatial primitives in Google's S2 geometry library (see http://s2geometry.io <http://s2geometry.io/>). It appears to implement spherical polygons using the "interior is on the left" rule, supports polygons that are larger than a hemisphere, and supports boolean operations on polygons, i.e. many of the hard-to-do-well things have been done.

Cheers,
Serge


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