Re: [Lib2geom-devel] Subpath from path by length?

[Johan E. <jbc...@sw...>]

On 4-9-2012 21:14, mathog wrote:
> How in 2geom does one do (pseudocode)
>
> Geom::Path P;  //contains a path already, lines and/or Beziers
>
> Geom::Point from=P.begin();
> subpath = make_sub_path(P,from,start,end,&trunc);
>
> where:
>
> 1. subpath is the path: from + start -> from + end, where start & end
> are distances along P
> 2. trunc is set if the subpath would have extended beyond P.end().
>
> The original path P should not be modified.

Hi David,
   Have a look at Path::portion. The parameters are "time-values" along 
the path I believe, not distance. To match time values with distance 
along the path, you can do an arc_length_parametrization, but I think 
that is only available for Piecewise<D2<SBasis> > paths. But it may not 
be necessary to do that (expensive) operation, if you can derive your 
start/end points as time-values in a different way.

Ciao,
   Johan