[postgis] 'real' contains, touches, overlaps etc.

[Manuel Weindorf]

On Tuesday 28 August 2001 18:17, you wrote:
> > One question:
> > Is somebody actually working on the following operators ???
> > contain(g1,g2)
> > touches(g1,g2)
> > overlaps(g1,g2)
>
> We're waiting for the JTS (java topology suite) with is a robust
> implementation of a bunch of operators and function, including the
> above.  JTS is scheduled to be released in Sept, but it needs to be
> translated to C++ before it can go in postgis.
>
> > These functions are important for me (at least concerning the polygon
> > type), and so I just started implementing them (based on the postgis-cvs
> > version). I don't know how far I get but, if there's another one doing
> > the same, please let me know (because of the reinvented wheels ;-)
>
> Go for it!  You might want to look at the distance functions for a
> starting place.  There is also the truely_inside() function.
>
> dave
>

Hi,

today I implemented the contains and the overlaps function (it was not so 
hard while using the PIP stuff already there. I test it for a while and send 
you the code soon (If you want it ;-) ...

But I recognized one thing:

The PIP test does just divide between two cases -> inside and outside
One problem (concerning to OGC conformity) is that we need a on-boundary 
operator to implelement touches(g1,g2) and the others in the coorect way.

I'm thinking about that (maybe I should wait, but I need it before ..)

bye
Manuel
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