Geometry Boost List: [ggl] Projections: Patch to get access to parameters

Subject: [ggl] Projections: Patch to get access to parameters
From: Chris Browet (cbro)
Date: 2009-06-17 05:20:29

2009/6/17 Barend Gehrels <Barend.Gehrels_at_[hidden]>

> Problem:
>> - As I don't have the "parameters" template parameter in projection.hpp,
>> it is hardcoded.
>>
>
> Sounds perfect. I'm glad there is interest in the projections. Note that
> (besides that the whole library is still in 'preview' phase) this projection
> stuff is implemented and tested by unit-tests, but not yet used in practice,
> as far as I know. So thanks for your efforts!

Well, it is used in Merkaartor (svn version) ;-)

>
>
> Note also that it will change. The ellipses and earth models, for example,
> will be Concepts which can be extended or provided by library users, and
> harmonized by the spherical distance functions in the algorithms/strategies.
> Furthermore there were some remarks about the "proj4-like" parameters. You
> profit from it but we also need to give an alternative to non-proj4 users.
> We want to support WKT-projection configurations as well.
>

Unfortunately, I'm not at all familiar with boost, so
"concepts/algorithms/strategies" concepts are unknown to me. I'll try to
learn...

It would definitely be great to have WKT projection support!
BTW, note that I encountered some discrepencies  between ESRI WKT in
Shapefiles and OSGeo standard. This might be interesting to tackle this.
GDAL uses a special "morphFromESRI()" function for this.

>
>
>
>
>
>> BTW, I don't quite get the reasoning behind templatizing the "parameters"
>> struct... It's quite static and expected by all proj4 related functions. It
>> only obfuscates/complicates the code, IMHO.
>>
> Sure, this was done because the reasons above, the parameters structure is
> not completely worked out. It can change.

OK. Then, it would probably be necessary to somehow have acces to them at
the projection level..

>
>
>  Thanks for all. Can you, by the way, already see if the clipping of
> polygons (without holes) is completely solved now?

Yes, it is solved. I couldn't reproduce my problem anymore (I din't see
other so far). Thanks for this

Regards
- Chris -
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