Geometry Boost List: [ggl] intersection_segment...

Subject: [ggl] intersection_segment...
From: Chris Browet (cbro)
Date: 2009-06-25 11:25:13

For my application, I currently only need points (I'm checking intersection
between roads for a specific function).

I can see an application for a linestring and/or segment output but it's not
implemented (or foreseen to be).

BTW, what is the conceptual difference between a segment and a 2-point (or 1
"segment") linestring)?
Conceptually, shouln't a linestring be a vector of segments?

Thanks
- Chris -

2009/6/25 Barend Gehrels <Barend.Gehrels_at_[hidden]>

>  Hi Chris,
>
> BTW, linestring by linestring, which is what I actually need (I am now
> doing linestring segment by linestring segment intersection) would be great.
>
> OK, that option will come as well (but don't know if that is in next half
> day ;-) )
>
> Do you need *intersection points* as output of linestring/linestring?
> Because it is also thinkable to get *intersection linestrings* or even *
> segments*...
>
> Regards, Barend
>
>
>
>
> But I can live with segment by segment...
>
> 2009/6/25 Barend Gehrels <Barend.Gehrels_at_[hidden]>
>
>> Hi Chris,
>>
>> Sorry for the inconvenience. It was very old.
>>
>> It will be replaced by a generic segment/segment intersection, delivering
>> one or two points.
>>
>> This functionis there already but as a strategy (because it is different
>> in Cartesian than in Spherical systems). In this strategy is specified what
>> you want (intersection points, or just how they intersect). It is internal,
>> so more complicated. You might call this directly using
>>
>> #include <ggl/strategies/cartesian/cart_intersect.hpp>
>> #include <ggl/strategies/intersection_result.hpp>
>>
>> #include <ggl/policies/relate/intersection_points.hpp>
>> ...
>>
>>     ggl::segment_intersection_points<P> is
>>         = ggl::strategy::intersection::relate_cartesian_segments
>>         <
>>             ggl::policies::relate::segments_intersection_points
>>                 <
>>                     segment_type,
>>                     segment_type,
>>                     ggl::segment_intersection_points<P>
>>                 >
>>         >::relate(segment_type(p1,p2), segment_type(p3,p4));
>>
>>
>> But maybe it is better to wait for half a day, I'll try make a wrapper
>> soon.
>>
>> The generic linestring/linestring would be an option but also not yet
>> there.
>>
>> Regards, Barend
>>
>>
>>
>> Chris Browet wrote:
>>
>>  ... seem to have disappeared in latest SVN.
>>
>> As I understand the intersection algorithm is now generic, should it be
>> replaced by a linestring/linestring intersection?
>>
>> - Chris -
>>
>> ------------------------------
>>
>>
>>
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>>
>>
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