/* Mathematiques de l'informatique graphique    */
/* Transformation de visualisation              */
/* en perspective                               */
/*                                              */
/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Octobre 2011                                 */

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

#include "TransformationGeometrique.h"
#include "ProjectionPerspective.h"
#include "Position3D.h"
#include "Direction3D.h"

ProjectionPerspective::ProjectionPerspective(Position3D *po,Position3D *pv,double d):TransformationGeometrique() {
  Direction3D n(po,pv);
  n.normalisation();
  double a = 1.0/sqrt(1.0-n.c[1]*n.c[1]);
  c[0][0] = -a*n.c[2];
  c[0][1] = 0.0;
  c[0][2] = a*n.c[0];
  c[0][3] = a*(po->c[0]*n.c[2]-po->c[2]*n.c[0]);
  c[1][0] = -a*n.c[0]*n.c[1];
  c[1][1] = 1.0/a;
  c[1][2] = -a*n.c[1]*n.c[2];
  c[1][3] = a*n.c[1]*(po->c[0]*n.c[0]+po->c[2]*n.c[2])-po->c[1]/a;
  c[2][0] = -n.c[0];
  c[2][1] = -n.c[1];
  c[2][2] = -n.c[2];
  c[2][3] = po->c[0]*n.c[0]+po->c[1]*n.c[1]+po->c[2]*n.c[2];
  c[3][0] = c[2][0]/d;
  c[3][1] = c[2][1]/d;
  c[3][2] = c[2][2]/d;
  c[3][3] = c[2][3]/d;
}

ProjectionPerspective::~ProjectionPerspective(void) {
}

void ProjectionPerspective::transforme(CoordonneesHomogenes *ch) {
  TransformationGeometrique::transforme(ch);
  ch->c[0] /= ch->c[3];
  ch->c[1] /= ch->c[3];
}