/* Gestion de deux fenetres                     */
/*                                              */
/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Mars 2019                                    */

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

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

/* Variables et constantes globales             */

static int f1;
static int f2;
static float rx = 0.0F;
static float ry = 0.0F;
static float rz = 0.0F;

/* Fonction de rafraichissement des 2 fenetres  */

static void postRedisplay(void) {
  glutPostWindowRedisplay(f1);
  glutPostWindowRedisplay(f2);
}

/* Fonction executee lors de l'appui            */
/* d'une touche de curseur ou d'une touche      */
/* page up ou page down                         */

static void special(int key,int x,int y) {
  switch(key) {
    case GLUT_KEY_UP :
      rx++;
      postRedisplay();
      break;
    case GLUT_KEY_DOWN :
      rx--;
      postRedisplay();
      break;
    case GLUT_KEY_LEFT :
      ry++;
      postRedisplay();
      break;
    case GLUT_KEY_RIGHT :
      ry--;
      postRedisplay();
      break;
    case GLUT_KEY_PAGE_UP :
      rz++;
      postRedisplay();
      break;
    case GLUT_KEY_PAGE_DOWN :
      rz--;
      postRedisplay();
      break; }
}

/* Fonction d'initialisation des parametres     */
/* OpenGL ne changeant pas au cours de la vie   */
/* du programme                                 */

static void init(void) {
}

/* Scene dessinee                               */

static void scene(void) {
  glPushMatrix();
  glutWireCube(7.0);
  glPopMatrix();
}

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

static void display1(void) {
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glPushMatrix();
  glRotatef(rx,1.0F,0.0F,0.0F);
  glRotatef(ry,0.0F,1.0F,0.0F);
  glRotatef(rz,0.0F,0.0F,1.0F);
  scene();
  glPopMatrix();
  glFlush();
  glutSwapBuffers();
  int error = glGetError();
  if ( error != GL_NO_ERROR )
    printf("Erreur OpenGL: %d\n",error);
}

/* Fonction executee lors d'un changement       */
/* de la taille de la fenetre OpenGL            */
/* -> Ajustement de la camera de visualisation  */

static void reshape1(int x,int y) {
  glViewport(0,0,x,y); 
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(-9.0,9.0,-9.0*(float) y/x,9.0*(float) y/x,-9.0,9.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

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

static void display2(void) {
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glPushMatrix();
  gluLookAt(0.0,0.0,10.0,0.0,0.0,0.0,0.0,1.0,0.0);
  glRotatef(rx,1.0F,0.0F,0.0F);
  glRotatef(ry,0.0F,1.0F,0.0F);
  glRotatef(rz,0.0F,0.0F,1.0F);
  scene();
  glPopMatrix();
  glFlush();
  glutSwapBuffers();
  int error = glGetError();
  if ( error != GL_NO_ERROR )
    printf("Erreur OpenGL: %d\n",error);
}

/* Fonction executee lors d'un changement       */
/* de la taille de la fenetre OpenGL            */
/* -> Ajustement de la camera de visualisation  */

static void reshape2(int tx,int ty) {
  glViewport(0,0,tx,ty); 
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  double ratio =(double) tx/ty;
  if ( ratio >= 1.0 )
    gluPerspective(80.0,ratio,0.01,20.0);
    else
    gluPerspective(80.0/ratio,ratio,0.01,20.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

/* Fonction executee en tache de fond           */
/* pour realiser une animation                  */

static void idle(void) {
  rx += 0.1F;
  ry += 0.15F;
  rz += 0.23F;
  postRedisplay();
}

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

static void keyboard(unsigned char key,int x,int y) {
  switch ( key ) {
    case 0x20 : {
      static int animation = 1;
      animation = !animation;
      glutIdleFunc(( animation ) ? idle : NULL); }
      break;
    case 0x1B :
      exit(0); 
      break; }
}

/* Fonction principale                          */

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  glutInitWindowSize(480,320); 
  glutInitWindowPosition(50,50); 
  f1 = glutCreateWindow("Fenêtre 1"); 
  init();
  glutKeyboardFunc(keyboard);
  glutSpecialFunc(special);
  glutReshapeFunc(reshape1);
  glutDisplayFunc(display1);
  glutInitWindowSize(320,240); 
  glutInitWindowPosition(250,100);
  f2 = glutCreateWindow("Fenêtre 2");
  init();
  glutKeyboardFunc(keyboard);
  glutSpecialFunc(special);
  glutDisplayFunc(display2);
  glutReshapeFunc(reshape2);
  glutIdleFunc(idle);
  glutMainLoop();
  return(0);
}
