CGAL users discussion list

[Efi Fogel <>]

I have no problems compiling the code.

Which platform are you using ?

What errors are you getting.

PS, if you expect other people to look at the code, make it look nice.

   ____  _        ____             _
  /_____/_) o    /__________  __  //
 (____ (   (    (    (_/ (_/-(-'_(/
                         _/

On Thu, Dec 3, 2015 at 2:52 PM, DamienDous <> wrote:

Hi Efi,

I attach the file containing the code.

Thank you for your help.

Damien
Efi Fogel wrote
> On Thu, Dec 3, 2015 at 1:22 PM, DamienDous &lt;

> damien.d@

> &gt; wrote:
>
>> Hi Efi,
>>
>> Thank you for your answer!
>>
>> I tried the example using
>> Exact_predicates_exact_constructions_kernel_with_sqrt and I have a
>> compilation error. It seems that the function
>> linear_least_squares_fitting_2
>> doesn't take this Kernel. Am I using it in the good way?
>>
>
> I don't know.
> I was able to compile something.
> Attach the code, and I'll try it myself.
>
>>
>> I also tried to convert the lines from Epick to Epeck using the mechanism
>> provided in the Algebraic Foundation package but as new user in CGAL I'm
>> kind of lost. I tried to use fraction decomposition in order to decompose
>> lines coefficients with Epick kernel and then recompose the coefficients
>> with Epeck Kernel but that didn't work. Is that the good way to convert
>> the
>> lines from one Kernel to another?
>>
>> Damien
>>
>>
>>
>> Efi Fogel wrote
>> > Hi Damien,
>> >
>> > Use the Exact_predicates_exact_constructions_kernel_with_sqrt kernel
>> or,
>> > when exactness can be compromised in favor of using a kernel that is
>> more
>> > efficient for constructing the arrangement, convert the lines from one
>> > representation to the other using the mechanism provided in the
>> Algebraic
>> > Foundation package.
>> >
>> > Please paste pretty code. (Not only not nicely indented, but also it
>> seems
>> > that the '<' and '>' tags go converted by Nabble to &lt; and &gt; and,
>> in
>> > addition, the ssl header inclusion is missing.)
>> >
>> > Efi
>> >
>> >    ____  _        ____             _
>> >   /_____/_) o    /__________  __  //
>> >  (____ (   (    (    (_/ (_/-(-'_(/
>> >                          _/
>> >
>> >
>> >
>> > On Tue, Dec 1, 2015 at 7:58 PM, DamienDous &lt;
>>
>> > damien.d@
>>
>> > &gt; wrote:
>> >
>> >> Hi,
>> >>
>> >> I need to create an arrangement with lines fitted by
>> >> linear_least_squares_fitting_2 function.
>> >>
>> >> I have a problem when I fit lines on points by using
>> >> linear_least_squares_fitting_2 function and after put the obtained
>> lines
>> >> in
>> >> an arrangement using an Exact_predicates_exact_constructions_kernel.
>> The
>> >> face number processed is incorrect.
>> >>
>> >> The following example fit three lines intersecting at the same point
>> >> using
>> >> Line_2 with Exact_predicates_inexact_constructions_kernel (the
>> >> linear_least_squares_fitting_2 can't take line with
>> >> Exact_predicates_exact_constructions_kernel because the function
>> >> processes
>> >> square root). To put the obtained lines in an arrangement using
>> >> Exact_predicates_exact_constructions_kernel , I convert the lines in
>> >> Segment_2 with Exact_predicates_exact_constructions_kernel and I
>> >> understand
>> >> that the problem come from this transformation but I don't know how to
>> >> use
>> >> linear_least_squares_fitting_2 function and then put the result in an
>> >> arrangement using Exact_predicates_exact_constructions_kernel.
>> >>
>> >> Also, I tried to use an arrangement with
>> >> Exact_predicates_inexact_constructions_kernel but that doesn't work
>> given
>> >> that the precision problem.
>> >>
>> >>
>> >> Here is my code :
>> >>
>> >> #include &lt;CGAL/Arrangement_2.h&gt;
>> >> #include &lt;CGAL/Arr_segment_traits_2.h&gt;
>> >> #include &lt;CGAL/Arr_linear_traits_2.h&gt;
>> >> #include &lt;CGAL/Exact_predicates_exact_constructions_kernel.h&gt;
>> >> #include &lt;CGAL/Exact_predicates_inexact_constructions_kernel.h&gt;
>> >> #include &lt;CGAL/Arr_extended_dcel.h&gt;
>> >>
>> >> typedef CGAL::Exact_predicates_inexact_constructions_kernel
>> >>  Kernel1;
>> >> typedef CGAL::Exact_predicates_exact_constructions_kernel
>> >>  Kernel2;
>> >> typedef CGAL::Arr_linear_traits_2
>> >
> <Kernel2>
>> >>       Traits;
>> >> typedef CGAL::Arr_face_extended_dcel&lt;Traits, bool&gt;
>> >> Dcel_2;
>> >> typedef CGAL::Arrangement_2&lt;Traits, Dcel_2&gt;
>> >>  Arrangement;
>> >>
>> >>
>> >> int            main()
>> >> {
>> >>         // Initialize segments distance and segments number of points
>> >>         double distance = 1;
>> >>         size_t nbPoints = 100;
>> >>
>> >>         // Fill the three points vectors representing the three lines
>> >>
>> >> std::vector&lt;std::vector&amp;lt;CGAL::Point_2&amp;lt;Kernel1&gt;>>
>> >> lines_points;
>> >>         lines_points.resize(3);
>> >>         double x = 0;
>> >>         for (size_t i = 0; i < nbPoints; i++, x += distance /
>> nbPoints)
>> {
>> >>                 lines_points.at(0).push_back(CGAL::Point_2
>> >
> <Kernel1>
>> > (distance
>> >> - x, x));
>> >>                 lines_points.at(1).push_back(CGAL::Point_2
>> >
> <Kernel1>
>> > (x,
>> >> x));
>> >>                 lines_points.at(2).push_back(CGAL::Point_2
>> >
> <Kernel1>
>> > (x,
>> >> distance / 2));
>> >>         }
>> >>
>> >>         // Fit for each points vector a line using
>> >> linear_least_squares_fitting_2
>> >>         // and transform this line in segment with
>> >> Exact_predicates_exact_constructions_kernel
>> >>         CGAL::Line_2
>> >
> <Kernel1>
>> >  line;
>> >>         std::vector&lt;CGAL::Segment_2&amp;lt;Kernel2&gt;>
>> >> segments(lines_points.size());
>> >>         for (size_t i = 0; i < lines_points.size(); i++) {
>> >>                 CGAL::linear_least_squares_fitting_2(lines_points.at
>> >> (i).begin(),
>> >> lines_points.at(i).end(), line, CGAL::Dimension_tag<0>());
>> >>                 segments.at(i) =
>> >> CGAL::Segment_2
>> >
> <Kernel2>
>> > (CGAL::Point_2
>> >
> <Kernel2>
>> > (0,
>> >> -line.c() / line.b()),
>> >>                         CGAL::Point_2
>> >
> <Kernel2>
>> > (distance, -(distance *
>> >> line.a() + line.c()) /
>> >> line.b()));
>> >>         }
>> >>
>> >>         // Put the processed segment in an arrangement
>> >>         Arrangement arr;
>> >>         CGAL::insert(arr, segments.begin(), segments.end());
>> >>
>> >>         // Print the number of bounded face
>> >>         std::cout << arr.number_of_faces() -
>> >> arr.number_of_unbounded_faces() <<
>> >> std::endl;
>> >>
>> >>         // Print the bounded face of the arrangement
>> >>         Arrangement::Ccb_halfedge_const_circulator curr;
>> >>         for (Arrangement::Face_const_handle fit = arr.faces_begin();
>> fit
>> >> !=
>> >> arr.faces_end(); ++fit) {
>> >>                 if (!fit->is_unbounded()) {
>> >>                         curr = fit->outer_ccb();
>> >>                         do {
>> >>                                 std::cout << curr->source()->point()
>> <<
>> "
>> >> - ";
>> >>                         } while (++curr != fit->outer_ccb());
>> >>                 }
>> >>         }
>> >> }
>> >>
>> >>
>> >>
>> >> Is there a Kernel that provide against this problem?
>> >>
>> >> Thank you very much.
>> >> Regards.
>> >>
>> >>
>> >>
>> >>
>> >> --
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>> >>
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>> >>
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>> >>
>> >>
>> >
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>>
>>
>>
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main.cpp <http://cgal-discuss.949826.n4.nabble.com/file/n4661437/main.cpp>



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