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[Pedro Machado Manhães de Castro <>]

Hello,

Be aware that what you pass as argument here:

SK::Sphere_3    s10( sphereCenter10, <<<<< CGAL::MP_Float(r1) >>>>> );

is the squared radius, not the radius.

If you replace r1 = 10.0 by r1 = 100.0 (or even r1 = 25.0), it works fine for me.

Best regards,
Pedro Machado

On Wed, Sep 2, 2009 at 2:15 PM, george13 <> wrote:

Hello,
I made a simple testing program in order to check the intersection of two
spheres. I used a sphere with center in ( 0.5, 0.0, 0.0 ) and another sphere
with center in ( -0.5, 0.0, 0.0 ) and both radius 1.0. Then I tested if they
are intersected using the predicate CGAL::do_intersect() and it worked.
Next, I consider a second peer of two spheres first with center in ( 5.0,
0.0, 0.0 ) and the second with center in ( -5.0, 0.0, 0.0 ) and both radius
10.0 and test again if they are intersected using the same predicate
do_intersect() but in this case it doesn't work. Choosing in this way this
values i made a upscale of 10 times and it doesn't work. I mentioned that
the code was compiled with VS 2008 under Windows XP SP3.
Could you help me with this problem?

My source code follows:
=============================================================
#include "stdafx.h"

#include <CGAL/Cartesian.h>
#include <CGAL/Algebraic_kernel_for_spheres_2_3.h>
#include <CGAL/Spherical_kernel_3.h>
#include <CGAL/MP_Float.h>
#include <CGAL/Quotient.h>

typedef CGAL::Quotient< CGAL::MP_Float> NT;
typedef CGAL::Cartesian<NT> Linear_k;
typedef CGAL::Algebraic_kernel_for_spheres_2_3<NT> Algebraic_k;
typedef CGAL::Spherical_kernel_3<Linear_k,Algebraic_k> SK;

int main()
{
       double r0 = 1.0;
       SK::Point_3             sphereCenter00(  0.5, 0.0, 0.0 );
       SK::Point_3             sphereCenter01( -0.5, 0.0, 0.0 );

       SK::Sphere_3    s00( sphereCenter00, CGAL::MP_Float(r0) );
       SK::Sphere_3    s01( sphereCenter01, CGAL::MP_Float(r0) );

       if( CGAL::do_intersect( s00, s01 ) ){
               std::cout<<"\n s00, s01 intersect \n";
       }else{
               std::cout<<"\n s00, s01 NOT intersect \n";
       }

       double r1 = 10.0;
       SK::Point_3             sphereCenter10(  5.0, 0.0, 0.0 );
       SK::Point_3             sphereCenter11( -5.0, 0.0, 0.0 );

       SK::Sphere_3    s10( sphereCenter10, CGAL::MP_Float(r1) );
       SK::Sphere_3    s11( sphereCenter11, CGAL::MP_Float(r1) );

       if( CGAL::do_intersect( s10, s11 ) ){
               std::cout<<"\n s10, s11 intersect \n";
       }else{
               std::cout<<"\n s10, s11 NOT intersect \n";
       }

       return 0;
}
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