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["Khlebnikov, Rostislav" <>]

Please let me know if a minimal code with data would help - I'd be happy to 
send it. 

Rostislav. 



> On 18 Sep 2014, at 18:25, "Rostislav Khlebnikov" 
> <>
>  wrote:
> 
> Hello,
> 
> I have some very weird behavior of the same code on different platforms and 
> for different build types.
> 
> So basically the code works fine only on one configuration out of four for 
> me. It is Release version on Windows (Windows, MSVS 2013, x64, CGAL 4.4 
> installed with the CGAL-4.4-Setup.exe installer and then built with CMake 
> and MSVS 2013).
> The Debug version always returns zero intersections. The code and the data 
> are literally the same.
> 
> I have also tried to build the Linux version. I used Ubuntu 13.10 x64, gcc 
> 4.8.1, libgmp and libmpfr installed using apt-get, and CGAL 4.4 compiled 
> from source using CMake. The only flag I changed when building CGAL and my 
> test application  is adding -std=c++11 - i.e. they are compiled with 
> -frounding-math.
> Here, none of the versions actually work. The Debug version reports 
> incorrect (I mean not even close to the windows ones) results or crashes 
> with segfault, and the Release version hangs on building the AABB tree if I 
> use my custom iterator or crashes with segfault is I use a simple std::list 
> of triangles.
> 
> Do you have any hints why this might happen?
> 
> Thank you for your help,
>   Rostislav.
> 
>> On 10/08/2014 15:24, Rostislav Khlebnikov wrote:
>> Hello Sebastien,
>> 
>> yes, indeed - it is the tree.build() call that makes everything logical.
>> Honestly, I just should RTFM better - I thought that 
>> accelerate_distance_queries() call was responsible for this, which does no 
>> good for intersections anyway and just eats more memory for KD tree.
>> So, I reverted to the iterator which returns triangles by value 
>> constructing them on-the-fly and set the CGAL::Tag_true as the last 
>> template parameter for primitive.
>> The test results with are mixed (Isect shows the average over 100 
>> all_intersections() calls, timed with QueryPerformanceCounter):
>> 
>> NO CACHE:
>> Build tree: 8.97505s
>> nConversions: 82950772
>> Isect: 2.97875ms
>> 
>> CGAL CACHE:
>> Build tree: 8.69819s
>> nConversions: 72620628
>> Isect: 1.97289ms
>> 
>> WITHIN-ITERATOR CACHE:
>> Build tree: 0.647395s
>> nConversions: 568938
>> Isect: 1.81151ms
>> 
>> Hope this helps,
>>   Rostislav.
>> 
>> 
>>> On 10/08/2014 14:39, Sebastien Loriot (GeometryFactory) wrote:
>>>> On 08/09/2014 05:59 PM, Rostislav Khlebnikov wrote:
>>>> Hello again,
>>>> 
>>>> I am just quite curious that the first call to the all_intersections is
>>>> very very slow compared to the rest. For example for mesh with about
>>>> 500k triangles, the first call takes about 10 seconds, while the all the
>>>> following ones with the same cutting query take about 3 milliseconds,
>>>> giving the difference of 3000 times! Is there some lazy processing going
>>>> on that are triggered by the first call? Is this normal anyway?
>>> 
>>> Try to call tree.build() before, it is probably the construction of the
>>> tree that is happening at the first call.
>>> 
>>> Sebastien.
>>> 
>>>> Additionally, by adding the cached converted triangle as a member of
>>>> Triangles_const_iterator, setting the reference template parameter to
>>>> default and returning K::Triangle_3 const& from derefence() will speed
>>>> up the first 10 times (down to 1 second) and also speed up the
>>>> subsequent calls to about 2 milliseconds. It is clear why this happens,
>>>> but I just wanted to mention it.
>>> 
>>> Note that the last template parameter of AABB_triangle_primitive can be
>>> used to cache the triangle in the primitive. Could you give it a try
>>> and confirm it is as fast as your setting?
>>> 
>>> Thanks,
>>> 
>>> Sebastien.
>>> 
>>>> So, if you could answer the questions in the first paragraph - that
>>>> would be absolutely great!
>>>> 
>>>> Thank you,
>>>>    Rostislav.
>>>> 
>>>>> On 08/08/2014 00:30, Rostislav Khlebnikov wrote:
>>>>> Hello Sebastien,
>>>>> 
>>>>> yes, indeed changing the signature of the Triangles_const_iterator to
>>>>> 
>>>>> class Triangles_const_iterator
>>>>>    : public boost::iterator_facade<
>>>>>      Triangles_const_iterator
>>>>>    , K::Triangle_3 const           // Value
>>>>>    , boost::forward_traversal_tag  // CategoryOrTraversal
>>>>>    , *K::Triangle_3*
>>>>>    >
>>>>> 
>>>>> helped resolving the issue. Just writing this to say thanks to you and
>>>>> perhaps help anyone looking into similar problem.
>>>>> 
>>>>> Thanks again,
>>>>>  Rostislav.
>>>>> 
>>>>> PS: still weird that it worked in release :)
>>>>> 
>>>>>> On 07/08/2014 23:33, Sebastien Loriot (GeometryFactory) wrote:
>>>>>> Thanks for the minimal reproducible example!
>>>>>> 
>>>>>> Actually, if you read again the doc of boost::iterator_facade
>>>>>> you'll see you're using the default for reference, which is
>>>>>> value&. In your case, reference should be value (Triangle is a
>>>>>> temporary).
>>>>>> 
>>>>>> Sebastien.
>>>>>> 
>>>>>>> On 08/07/2014 11:14 PM, Rostislav Khlebnikov wrote:
>>>>>>> Hi everyone,
>>>>>>> 
>>>>>>> I'm using AABB_tree to compute intersections of a VTK poly data with a
>>>>>>> plane. When I just convert the triangles from VTK to CGAL and store
>>>>>>> them
>>>>>>> in std list, everything works fine. However, I would like to reduce
>>>>>>> storage requirements by creating a triangle iterator that iterates 
>>>>>>> over
>>>>>>> the VTK triangle data.
>>>>>>> Code in main.cpp here shows how I do it http://pastebin.com/kNLQevXV
>>>>>>> <http://pastebin.com/sKPFHTT2>
>>>>>>> 
>>>>>>> In Release version everything works fine, but in Debug version -
>>>>>>> intersections are never found! (Funnily enough it's a debug version
>>>>>>> that
>>>>>>> fails). I tried finding the problem - but I don't seem to understand
>>>>>>> it.
>>>>>>> What I found is that when CGAL uses the kernel to convert from
>>>>>>> Triangle_3 to TriangleC3 with rep() and then uses this TriangleC3's
>>>>>>> vertex() method on line 1909 in function_objects.h, the TriangleC3
>>>>>>> 'base' variable becomes corrupted during get(base) call at line 94 in
>>>>>>> Triangle_3.h (i.e. correct coordinates are overwritten in what seems 
>>>>>>> to
>>>>>>> be stack initialization in function call when I looked at 
>>>>>>> disassembly).
>>>>>>> 
>>>>>>> Is it something wrong that I do with my custom iterator? Or perhaps
>>>>>>> it's
>>>>>>> a bug in VS2013 compiler (I saw some bug reports regarding stack
>>>>>>> corruption for VS2012 such as this
>>>>>>> <http://stackoverflow.com/questions/11000798/structure-parameter-corrupted-on-function-call>,
>>>>>>>  
>>>>>>> 
>>>>>>> so perhaps it's not completely resolved).
>>>>>>> 
>>>>>>> I attached all the code, input files and cmake file, so if someone who
>>>>>>> has VTK and CGAL could quitckly test it on their platform. For me the
>>>>>>> release version returns 54 intersections and debug - 0.
>>>>>>> 
>>>>>>> Thank you in advance,
>>>>>>>    Rostislav.
>>>>>>> 
>>>>>>> CGAL installation info:
>>>>>>> Windows 8.1, MSVS 2013, x64
>>>>>>> CGAL 4.4 installed with the CGAL-4.4-Setup.exe installer and then
>>>>>>> built
>>>>>>> with CMake and MSVS 2013.
> 
> 
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