CGAL users discussion list

[Andreas Fabri <>]

Gueroult Renaud wrote:
> Yes the VC2005 project options are release, O2 and I had the NDEBUG flag 
> on for the time given previously.
> If I change this flag to DNDEBUG it takes about 18 seconds to make 1000 
> intersections in release under windows with O2.
>
> Thanks for your help. I'm at your disposal if you need anything else.


Did you define CGAL_USE_GMP ?  Otherwise
the exact predicates exact constructions kernel
might use another multi precision integer
number type under the hood.


Do you use the same GMP for VC8 and cygwin?
The precompiled version that comes with the
windows installer doesn't use processor specific
optimisations, that is no assembler routines.

andreas

> Renaud
>
> Andreas Fabri a écrit :
> > Did you -O2  -DNDEBUG
> >
> > andreas
> >
> >
> > Gueroult Renaud wrote:
> > > Hi CGAL users and developpers,
> > >
> > > I've got a speed issue running some polygons operations. Using the
> > > CGAL-3.3 in release with CGAL_NO_ASSERTIONS and CGAL_NO_PRECONDITIONS, I
> > > get an approximate computation time of 15 seconds for 1000 intersections
> > > of really simple polygons on  a windows OS under VS2005. I tried it
> > > using cygwin (liux environment for windows) with the same computer and
> > > the same operation takes approximately 4 sec. Unfortunately I'd like to
> > > keep developping under windows and VS2005 because I'm using others
> > > library I don't want to implement with cygwin.
> > > If someone would like to see the options of the VS2005 project, tell me
> > > and I would be please to send  it to him.
> > > I tried with various kernels, it certainly has an impact on the
> > > computation time, but that is definitely not the explanation for this
> > > huge difference.
> > >
> > > Best regards,
> > >
> > > Renaud
> > >
> > >
> > > Below is the code sample:
> > >
> > > /#include "stdafx.h"
> > > #include <CGAL/Exact_predicates_exact_constructions_kernel.h>
> > > #include <CGAL/Cartesian.h>
> > > #include <CGAL/Polygon_2.h>
> > > #include <CGAL/Polygon_with_holes_2.h>
> > > #include <CGAL/Boolean_set_operations_2.h>
> > > #include <iostream>
> > > #include "time.h"
> > > #include "bso_rational_nt.h"
> > >
> > > typedef CGAL::Cartesian<double> K;
> > > typedef CGAL::Exact_predicates_exact_constructions_kernel  Kernel;
> > > typedef Kernel::Point_2 Point_2;
> > > typedef CGAL::Polygon_2<Kernel> Polygon_2;
> > > typedef CGAL::Polygon_with_holes_2<Kernel> Polygon_with_holes_2;
> > > typedef std::list<Polygon_with_holes_2>        Pwh_list_2;
> > > using std::cout; using std::endl;
> > >
> > >
> > > int main()
> > > {
> > >    Polygon_2 P3,P4;
> > >    P3.push_back(Point_2(0,0));
> > >    P3.push_back(Point_2(1,0));
> > >    P3.push_back(Point_2(1,1));
> > >    P3.push_back(Point_2(0,1));
> > >    P4.push_back(Point_2(0.5,0.5));
> > >    P4.push_back(Point_2(1.5,0.5));
> > >    P4.push_back(Point_2(1.5,1.5));
> > >    P4.push_back(Point_2(0.5,1.5));
> > >
> > >    Polygon_with_holes_2 UnionR;
> > >    Pwh_list_2 intR;
> > >
> > >    int i,j;
> > >    time_t Start_t, End_t;
> > >    int time_task1;
> > >    FILE *out = fopen("D:\\code\\TimeTestFromScratch\\Test.txt","w");
> > >    for (i=0;i<5;i++)
> > >    {
> > >        Start_t = time(NULL);
> > >        for (j=0;j<1000;j++)
> > >        {    //UnionR.clear();
> > >            //CGAL::join(P3,P4,UnionR);
> > >            intR.clear();
> > >            CGAL::intersection(P3,P4,std::back_inserter(intR));
> > >        }
> > >        End_t = time(NULL);
> > >        time_task1 = difftime(End_t, Start_t);
> > >        fprintf(out,"Elpased : %d\n",time_task1);
> > >    }
> > >
> > >    return 1;
> > > }/