
Geometry : 
Subject: Re: [geometry] nsphere and views names
From: Adam Wulkiewicz (adam.wulkiewicz_at_[hidden])
Date: 20130623 13:03:21
2013/6/23 Barend Gehrels <barend_at_[hidden]>
>
>
> What is the difference between view::as_centroid and the normal
> return_centroid? Same question for envelope. IMO all these calls are
> redundant  we have this already. What does as_bounds do?
>
>
The functions we have converts one Geometry into another. View preferably
would store reference and provide needed data without conversion. And if
someone wanted to convert the geometry because he want to reuse it somehow,
he probably should use other method than view.
view::as_centroid for sphere would just access center's coordinates using
get<>(), for box it could calculate it on the fly using min and max
coordinate, all without the conversion, and storing of additional Point.
For any geometry using Points range, this could also be calculated on the
fly for one Dimension, in some cases this could be preferable, e.g. when
coordinates musn't be calculated for all dimensions.
The same is true with envelope, e.g. envelope's min and max corners for
Sphere, Point, even for Polygons could be calculated on the fly, there is
no need to create additional Box, especially for Points.
As for bounds(). I'm using this kind of function in the Index. It is a
generalization of envelope() and can calculate bounding objects of
arbitrary type, e.g. bounding box or sphere.
Regards,
Adam
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