Converting between Rational and Floating Point Kernel

If p is a point or rat_point then point p.to_point(); returns a point.

If p is a point the call is equivalent to the call of the copy constructor, and if p is a rat_point, the Cartesian coordinates of the point returned are the floating point approximations of the Cartesian coordinates of p.

Remark 1: The conversion from rational objects to floating point objects needs to be used whenever an object is to be displayed in a window. If W is a window and p is a point or a rat_point, then W << p.to_point(); draws p in W.

Example:

#include <LEDA/graphics/window.h>
#include <LEDA/geo/rat_point.h>

using namespace leda;

int main()
{ 
  rat_point rp(50,50);

  window W(100,100);
  W.open();
  W << rp.to_point();
  //W << rp; does not work
  W.display();
  W.read_mouse();

  return 0;
}	  

Remark 2: We could write W << p; if the class rat_point provided a conversion operator to point. We opted for the less elegant code, since the use of conversion operators can lead to unexpected side effects.

See also:

Data Types for 2D Geometry

Window

Geometry

Advanced Data types for 2-D geometry

Data Types for 3-D Geometry

Geometry Algorithms

GeoWin