Geometry Boost List: [ggl] Segment Transformation

Subject: [ggl] Segment Transformation
From: Barend Gehrels (barend)
Date: 2011-09-16 01:54:31

Hi Bernhard,

>
> I'm trying to transform segments, but it doesn't work. Is this a bug, or am
> I doing something wrong?
> Slightly changed transformation example:
>
> #include<boost/geometry.hpp>
> int main()
> {
>      namespace trans = boost::geometry::strategy::transform;
>      using boost::geometry::dsv;
>
>      typedef boost::geometry::model::point<double, 2,
> boost::geometry::cs::cartesian> point_type;
>      typedef boost::geometry::model::segment<point_type>  segment_type;
>
>      point_type p1(1.0, 1.0);
>      point_type p2(2.0, 2.0);
>      segment_type s1(p1, p2);
>      segment_type s2;
>
>      // Translate over (1.5, 1.5)
>      trans::translate_transformer&lt;segment_type, segment_type&gt;
> translate(1.5, 1.5);
>      //trans::rotate_transformer&lt;segment_type, segment_type,
> boost::geometry::degree&gt; rot(90);
>      boost::geometry::transform(s1, s2, translate);
>
>      return 0;
> }
>

The transformers should be declared like this:

trans::translate_transformer<point_type, point_type>  translate(1.5, 1.5);

It then works perfectly.

So the rationale is that this strategy (most, nearly all) are declared 
using a point-type as a template parameter. The free functions then work 
on any parameter type.

Regards, Barend