/* Clipping d'un segment de droite              */
/* dans un rectangle                            */
/* par l'algorithme de Cohen-Sutherland         */
/*                                              */
/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Novembre 2010                                */

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

#include <GL/glut.h>
#include <GL/gl.h>
#include <GL/glu.h>

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

/* Variables globales                           */

static int sc = 0;

/* Fonction executee lors d'un changement       */
/* de la taille de la fenetre OpenGL            */
/* Configuration d'une camera de visualisation  */
/* en projection en parallele orthographique    */

void reshape(int tx,int ty) {
  glViewport(0,0,tx,ty);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho((-tx/2)/10.0,(-tx/2+tx)/10.0,
          (-ty/2)/10.0,(-ty/2+ty)/10.0,
          -1.0,1.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

/* Fonction executee lors d'un rafraichissement */
/* de la fenetre de dessin                      */

void display(void) {
  glClearColor(0.6F,0.6F,0.6F,1.0F) ;
  glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT) ;
  Position2D *ps11 = new Position2D(-15.0,9.0);
  Position2D *ps12 = new Position2D(10.0,-10.0);
  Segment2D *s1 = new Segment2D(ps11,ps12);
  Position2D *ps21 = new Position2D(3.0,2.0);
  Position2D *ps22 = new Position2D(15.0,6.0);
  Segment2D *s2 = new Segment2D(ps21,ps22);
  Position2D *ps31 = new Position2D(-17.0,-5.0);
  Position2D *ps32 = new Position2D(-7.0,-13.0);
  Segment2D *s3 = new Segment2D(ps31,ps32);
  Position2D *pr1 = new Position2D(-12.0,-7.0);
  Position2D *pr2 = new Position2D(11.0,5.0);
  Rectangle2D *r = new Rectangle2D(pr1,pr2);
  glPushMatrix();
  glColor3f(0.0F,0.0F,1.0F);
  r->trace();
  if ( ( sc == 0 ) || ( sc == 2 ) ) {
    glColor3f(1.0F,0.0F,0.0F);
    s1->trace();
    s2->trace();
    s3->trace(); }
  if ( ( sc == 1 ) || ( sc == 2 ) ) {
    glColor3f(0.0F,1.0F,0.0F);
    if ( s1->clip(r) )
      s1->trace();
    if ( s2->clip(r) )
      s2->trace();
    if ( s3->clip(r) )
      s3->trace(); }
  glPopMatrix();
  delete(s1);
  delete(r);
  delete(ps11);
  delete(ps12);
  delete(ps21);
  delete(ps22);
  delete(ps31);
  delete(ps32);
  delete(pr1);
  delete(pr2);
  glFlush();
  glutSwapBuffers();
  int error = glGetError();
  if ( error != GL_NO_ERROR )
    printf("Attention, erreur OpenGL %d\n",error);
}

/* Fonction executee lors de la frappe          */
/* d'une touche alphanumerique du clavier       */

void keyboard(unsigned char key,int x,int y) {
  switch ( key ) {
    case 0x0D : sc = (sc+1)%3;
                glutPostRedisplay();
                break;
    case 0x1B : exit(0); }
}

/* Fonction d'initialisation d'OpenGL           */
void init(void) {
  glPointSize(10.0F);
}

/* Fonction principale                          */

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE|GLUT_DEPTH);
  glutInitWindowSize(400,300); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Cohen-Sutherland");
  init();
  glutReshapeFunc(reshape);
  glutKeyboardFunc(keyboard);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}