nr-types.cpp

/** \file
 * Implements NR::Point::normalize()
 */

#include <libnr/nr-types.h>

#include "isnan.h" //temporary fix for isnan()

/** Scales this vector to make it a unit vector (within rounding error).
 *
 *  The current version tries to handle infinite coordinates gracefully,
 *  but it's not clear that any callers need that.
 *
 *  \pre *this != Point(0, 0).
 *  \pre Neither coordinate is NaN.
 *  \post L2(*this) very near 1.0.
 */
00018 void NR::Point::normalize() {
      double len = hypot(_pt[0], _pt[1]);
      g_return_if_fail(len != 0);
      g_return_if_fail(!isNaN(len));
      static double const inf = 1e400;
      if(len != inf) {
            *this /= len;
      } else {
            unsigned n_inf_coords = 0;
            /* Delay updating pt in case neither coord is infinite. */
            NR::Point tmp;
            for ( unsigned i = 0 ; i < 2 ; ++i ) {
                  if ( _pt[i] == inf ) {
                        ++n_inf_coords;
                        tmp[i] = 1.0;
                  } else if ( _pt[i] == -inf ) {
                        ++n_inf_coords;
                        tmp[i] = -1.0;
                  } else {
                        tmp[i] = 0.0;
                  }
            }
            switch (n_inf_coords) {
            case 0:
                  /* Can happen if both coords are near +/-DBL_MAX. */
                  *this /= 4.0;
                  len = hypot(_pt[0], _pt[1]);
                  g_assert(len != inf);
                  *this /= len;
                  break;

            case 1:
                  *this = tmp;
                  break;

            case 2:
                  *this = sqrt(0.5) * tmp;
                  break;
            }
      }
}
/*
  Local Variables:
  mode:c++
  c-file-style:"stroustrup"
  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
  indent-tabs-mode:nil
  fill-column:99
  End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :