/* Segment en 2D                                */
/*                                              */
/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Novembre 2011                                */

#include <stdlib.h>
#include <stdio.h>
#include <math.h>

#include "Segment2D.h"
#include "Position2D.h"
#include "Rectangle2D.h"

Segment2D::Segment2D(void) {
  pi = new Position2D();
  pf = new Position2D();
}

Segment2D::Segment2D(Position2D *p1,Position2D *p2) {
  pi = new Position2D(p1);
  pf = new Position2D(p2);
}

Segment2D::Segment2D(Segment2D *s) {
  pi = new Position2D(s->pi);
  pf = new Position2D(s->pf);
}

Segment2D::~Segment2D(void) {
  delete(pi);
  delete(pf);
}

void Segment2D::print(void) {
  pi->print();
  printf("\n");
  pf->print();
  printf("\n");
}

static int round(double v) {
  return((int) (v + (( v > 0.0 ) ? 0.4999 : -0.4999)));
}

int code(Position2D *p,Rectangle2D *r) {
  int code = 0x0000; 
  if ( p->c[0] < r->ig->c[0] )
    code |= 0x0001;
  if ( p->c[0] > r->sd->c[0] )
    code |= 0x0002;
  if ( p->c[1] < r->ig->c[1] )
    code |= 0x0004;
  if ( p->c[1] > r->sd->c[1] )
    code |= 0x0008;
  return(code);
}

double Segment2D::abscisse(double y) {
  double a = (pf->c[1]-pi->c[1])/(pf->c[0]-pi->c[0]);
  double b = pi->c[1] - a*pi->c[0];
  return((y-b)/a);
}

double Segment2D::ordonnee(double x) {
  double a = (pf->c[1]-pi->c[1])/(pf->c[0]-pi->c[0]);
  double b = pi->c[1] - a*pi->c[0];
  return(a*x+b);
}

int Segment2D::clip(Rectangle2D *r) {
  int c1,c2;
  c1 = code(pi,r);
  c2 = code(pf,r);
  while ( ( c1 || c2 ) && ( (c1&c2) == 0 ) ) {
    if ( !c1 ) {
      Position2D p = *pi;
      *pi = *pf;
      *pf = p;
      int aux = c1;
      c1 = c2;
      c2 = aux; }
    if ( (c1&0x0001) != 0 ) {
      pi->c[1] = ordonnee(r->ig->c[0]);
      pi->c[0] = r->ig->c[0]; }
      else
      if ( (c1&0x0002) != 0 ) {
        pi->c[1] = ordonnee(r->sd->c[0]);
        pi->c[0] = r->sd->c[0]; }
        else
        if ( (c1&0x0004) != 0 ) {
          pi->c[0] = abscisse(r->ig->c[1]);
          pi->c[1] = r->ig->c[1]; }
          else
          if ( (c1&0x0008) != 0 ) {
            pi->c[0] = abscisse(r->sd->c[1]);
            pi->c[1] = r->sd->c[1]; }
    c1 = code(pi,r); }
  return ( !c1 && !c2);
}