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Cartesian_converter<K1, K2, NTConverter>converts objects from the kernel traits K1 to the kernel traits K2 using Converter to do the conversion. Those traits must be of the form Cartesian<FT1> and Cartesian<FT2> (or the equivalent with Simple_cartesian). It then provides the following operators to convert objects from K1 to K2.
The third template parameter NTConverter is a function object that must provide K2::FT operator()(K1::FT n) that converts n to an K2::FT which has the same value.
The default value of this parameter is CGAL::NT_converter<K1::FT, K2::FT>.
#include <CGAL/Cartesian_converter.h>
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Default constructor.
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| returns a K2::Point_2 which coordinates are those of p, converted by NTConverter. | ||
Similar operators are defined for the other kernel traits types Point_3, Vector_2...
In the following example, we compute exactly the intersection point between a line and a triangle, and we then create a double approximation of this point.
File: examples/Kernel_23/cartesian_converter.cpp
#include <CGAL/Simple_cartesian.h>
#include <CGAL/Quotient.h>
#include <CGAL/MP_Float.h>
#include <CGAL/Cartesian_converter.h>
typedef CGAL::Simple_cartesian<double> IK;
typedef CGAL::Simple_cartesian<CGAL::Quotient<CGAL::MP_Float> > EK;
typedef CGAL::Cartesian_converter<IK,EK> IK_to_EK;
typedef CGAL::Cartesian_converter<EK,IK> EK_to_IK;
int main(){
IK::Triangle_3 t1(
IK::Point_3(0.,0.,0.),
IK::Point_3(1.,0.,-1.),
IK::Point_3(0.,1.,3.)
);
IK::Line_3 l1(
IK::Point_3(0.2,0.25,-7),
IK::Point_3(0.25,0.3,4)
);
IK_to_EK to_exact;
EK::Triangle_3 t2=to_exact(t1);
EK::Line_3 l2=to_exact(l1);
CGAL::Object inter=CGAL::intersection(t2,l2);
const EK::Point_3& exact_pt=CGAL::object_cast<EK::Point_3>(inter);
EK_to_IK to_inexact;
IK::Point_3 inexact_pt = to_inexact(exact_pt);
return 0;
}