CGAL users discussion list

[Peter Hachenberger <>]

Don't care about this any more. With Gmp the compiler sets the kernel
nicely.

Peter


On Tue, 2008-01-08 at 22:26 -0600, Gilbert Bernstein wrote:
> ET didn't mean anything to the compiler.
> 
> typedef CGAL::Lazy_kernel<CGAL::Simple_cartesian<ET> > Kernel;
> 
> Did you mean for some other number type there?  Also, I now have Gmp  
> and mpfr.
> 
> -- Gilbert
> 
> 
> On Jan 8, 2008, at 5:20 AM, Peter Hachenberger wrote:
> 
> Hi Gilbert,
> 
> now here we seem to have a bug, but not a bad one. I looked at your
> nef-files and the obvious reasons for the problem is, that the geometry
> in this file uses floating-point coordinates. The nef file-format is
> supposed to output the coordinates always as homogeneous integer
> coordinates. My code should recognize the used kernel and convert the
> coordinates for the output accordingly. This seems not to happen. When
> Rob tested your files, he used the off files, which have no problem.
> There may be two reasons for the problem:
> 
> 1. CGAL::Exact_predicates_exact_constructions_kernel evaluates to
> something unexpected and therefore the wrong specialization is used for
> the coordinate output.
> 
> 2. The kernel evaluates correctly, but somehow the compiler chooses the
> wrong specialization.
> 
> Let's find out, whether it's the first option. Please use the program
> below to convert any off-file to a nef-file and look up whether your
> output still uses floating point arithmetic.
> 
> Peter
> 
> #include <CGAL/Lazy_kernel.h>
> #include <CGAL/Simple_cartesian.h>
> #include <CGAL/Gmpq.h>
> #include <CGAL/Polyhedron_3.h>
> #include <CGAL/IO/Polyhedron_iostream.h>
> #include <CGAL/Nef_polyhedron_3.h>
> #include <CGAL/Nef_3/SNC_indexed_items.h>
> #include <CGAL/IO/Nef_polyhedron_iostream_3.h>
> 
> typedef CGAL::Lazy_kernel<CGAL::Simple_cartesian<ET> > Kernel;
> typedef CGAL::Polyhedron_3<Kernel>  Polyhedron;
> typedef CGAL::SNC_indexed_items Items;
> typedef CGAL::Nef_polyhedron_3<Kernel, Items>  Nef_polyhedron;
> 
> int main() {
> 
>    Polyhedron P;
>    std::cin >> P;
>    if(!P.is_closed())
>    {
>      std::cerr << "input polyhedron is not closed.  "
>                << "Cannot convert to Nef Polyhedron." << std::endl;
>      return 1;
>    }
> 
>    Nef_polyhedron N(P);
>    std::cout << N;
> }
> CGAL::Lazy_kernel<CGAL::Simple_cartesian<ET> >
> 
> 
> 
> On Mon, 2008-01-07 at 17:18 -0600, Gilbert Bernstein wrote:
> > Hello again,
> >
> >     I've been trying to get boolean operations up and working now, and
> > am running into a bit of trouble.  I was able to get a union of two
> > offset cubes to compute just fine, but when I tried to union a shark
> > model with a reflected version of itself I got the following error  
> > dump:
> >
> > CGAL error: assertion violation!
> > Expr: c.has_on(p1)&&c.has_on(p2)
> > File: /usr/local/CGAL-3.3.1/include/CGAL/Nef_S2/Sphere_segment.h
> > Line: 57
> > Explanation:
> > terminate called after throwing an instance of
> > 'CGAL::Assertion_exception'
> >    what():  CGAL ERROR: assertion violation!
> > Expr: c.has_on(p1)&&c.has_on(p2)
> > File: /usr/local/CGAL-3.3.1/include/CGAL/Nef_S2/Sphere_segment.h
> > Line: 57
> > CGAL error: assertion violation!
> > Expr: 0
> > File: /usr/local/CGAL-3.3.1/include/CGAL/Nef_3/SNC_io_parser.h
> > Line: 1277
> > Explanation:SNC_io_parser::read: no SNC header.
> > terminate called after throwing an instance of
> > 'CGAL::Assertion_exception'
> >    what():  CGAL ERROR: assertion violation!
> > Expr: 0
> > File: /usr/local/CGAL-3.3.1/include/CGAL/Nef_3/SNC_io_parser.h
> > Line: 1277
> > Explanation: SNC_io_parser::read: no SNC header.
> > Abort trap
> >
> > Following is a tarball of all relevant code and models.  The program
> > off2nef (included) was used to convert the shark into a Nef
> > polyhedron.  The reflection was performed before reading the shark
> > into CGAL. (ie. with off2nef)  The program "test" was then run on the
> > two .nef files to produce the above error message.
> >
> > If anyone has the time to peek at all this, or just has the time for
> > helpful suggestions, they would be much appreciated.
> >
> > -- Gilbert
> -- 
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