/********************************************************/
/*                     cube.c                           */
/********************************************************/
/* Affiche a l'ecran un cube en 3D                      */
/********************************************************/

/* inclusion des fichiers d'en-tete Glut */

#include <GL/glut.h>

/* Notre structure point */

typedef struct
{
  float x;
  float y;
  float z;
  float r;
  float g;
  float b;
} point;

point p[8]={
    {-0.5,-0.5, 0.5,1.0,0.0,0.0},
    {-0.5, 0.5, 0.5,0.0,1.0,0.0},
    { 0.5, 0.5, 0.5,0.0,0.0,1.0},
    { 0.5,-0.5, 0.5,1.0,1.0,1.0},
    {-0.5,-0.5,-0.5,1.0,0.0,0.0},
    {-0.5, 0.5,-0.5,0.0,1.0,0.0},
    { 0.5, 0.5,-0.5,0.0,0.0,1.0},
    { 0.5,-0.5,-0.5,1.0,1.0,1.0}};
  
int f[6][4]={
  {0,1,2,3},
  {3,2,6,7},
  {4,5,6,7},
  {0,1,5,4},
  {1,5,6,2},
  {0,4,7,3}};

char presse;
int anglex,angley,x,y,xold,yold;

/* Prototype des fonctions */
void affichage();
void clavier(unsigned char touche,int x,int y);
void reshape(int x,int y);
void idle();
void mouse(int bouton,int etat,int x,int y);
void mousemotion(int x,int y);

int main(int argc,char **argv)
{
  /* initialisation de glut et creation
     de la fenetre */
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE | GLUT_DEPTH);
  glutInitWindowPosition(200,200);
  glutInitWindowSize(250,250);
  glutCreateWindow("cube");

  /* Initialisation d'OpenGL */
  glClearColor(0.0,0.0,0.0,0.0);
  glColor3f(1.0,1.0,1.0);
  glPointSize(2.0);
  glEnable(GL_DEPTH_TEST);

  /* enregistrement des fonctions de rappel */
  glutDisplayFunc(affichage);
  glutKeyboardFunc(clavier);
  glutReshapeFunc(reshape);
  glutMouseFunc(mouse);
  glutMotionFunc(mousemotion);

  /* Entree dans la boucle principale glut */
  glutMainLoop();
  return 0;
}


void affichage()
{
  int i,j;
  /* effacement de l'image avec la couleur de fond */


/**********************************/
/**********************************/
/**********************************/
// here we ask to draw on front buffer

	//glDrawBuffer(GL_FRONT);
/**********************************/
/**********************************/
/**********************************/


  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  
  glLoadIdentity();
  glRotatef(-angley,1.0,0.0,0.0);
  glRotatef(-anglex,0.0,1.0,0.0);
  /* Dessin du cube */
  for (i=0;i<6;i++)
    {
      glBegin(GL_POLYGON);
      for (j=0;j<4;j++)
	{
	  glColor3f(p[f[i][j]].r,p[f[i][j]].g,p[f[i][j]].b);
	  glVertex3f(p[f[i][j]].x,p[f[i][j]].y,p[f[i][j]].z);
	}
      glEnd();
    }
  glFlush();
  
  /* On echange les buffers */
 // glutSwapBuffers();
}

void clavier(unsigned char touche,int x,int y)
{
  switch (touche)
    {
    case 'p': /* affichage du carre plein */
      glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);
      glutPostRedisplay();
      break;
    case 'f': /* affichage en mode fil de fer */
      glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);
      glutPostRedisplay();
      break;
    case 's' : /* Affichage en mode sommets seuls */
      glPolygonMode(GL_FRONT_AND_BACK,GL_POINT);
      glutPostRedisplay();
      break;
    case 'd':
      glEnable(GL_DEPTH_TEST);
      glutPostRedisplay();
      break;
    case 'D':
      glDisable(GL_DEPTH_TEST);
      glutPostRedisplay();
      break;
    //case 'q' : /*la touche 'q' permet de quitter le programme */
      //exit(0);
    }
}

void reshape(int x,int y)
{
  if (x<y)
    glViewport(0,(y-x)/2,x,x);
  else 
    glViewport((x-y)/2,0,y,y);
}

void mouse(int button, int state,int x,int y)
{
  /* si on appuie sur le bouton gauche */
  if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) 
  {
    presse = 1; /* le booleen presse passe a 1 (vrai) */
    xold = x; /* on sauvegarde la position de la souris */
    yold=y;
  }
  /* si on relache le bouton gauche */
  if (button == GLUT_LEFT_BUTTON && state == GLUT_UP) 
    presse=0; /* le booleen presse passe a 0 (faux) */
}

void mousemotion(int x,int y)
  {
    if (presse) /* si le bouton gauche est presse */
    {
      /* on modifie les angles de rotation de l'objet
	 en fonction de la position actuelle de la souris et de la derniere
	 position sauvegardee */
      anglex=anglex+(x-xold); 
      angley=angley+(y-yold);
      glutPostRedisplay(); /* on demande un rafraichissement de l'affichage */
    }
    
    xold=x; /* sauvegarde des valeurs courante de le position de la souris */
    yold=y;
  }