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Subject: [ggl] (spatial_)index::is_overlapping
From: Barend Gehrels (Barend.Gehrels)
Date: 2009-06-26 05:49:47

Hi Mateusz,

>>> Just a side note, How do we know that?
>> The speed: In "other/dev" I've my checking program for the polygon
>> "touches" algorithm. Not yet moved to "algorithms" (because the project
>> didn't go through) but it is working. In that I've done some comparisons
>> between spatial indexes / monotonic sections. I will write another mail
>> about this later or put it on our Wiki.
>> However, I can check the speed of spatial indexes there, and in case of
>> errors we (probably) get wrong results there. It is not yet a unit test
>> but you see immediately if the index does not work.
>> The correctness: Actually the "intersects", what this function is, is
>> just the ! disjoint. The disjoint is already implemented for box/box so
>> this is another simpler version.
>> template <typename Box>
>> inline bool is_overlapping(Box const& b1, Box const& b2)
>> {
>> return ! ggl::disjoint(b1, b2);
>> }
> Barend,
> Thanks for the in-depth explanation, thought I think I've misunderstood.
> In my question, I assumed you refer to the refactoring work that
> "dramatically reduce the numbers of "get".
> IOW, I asked why do you say that this refactoring improved speed :-)
> Anyway, misunderstanding.
If I understand you well... I measured that the speed was better...
Regards, Barend

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