CGAL users discussion list

[Rob Pieké <>]

CGAL ships with some demo programs that do OFF->Nef that you might want 
to look at. The first one I tried seemed to work with your models no 
problem.

nef_3_filtered loadoff shark_simple.off loadoff shark_rev.off union 
saveoff out.off

And out.off definitely looks like a mutant two-headed hammerhead shark.

Cheers!


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