/* Fonctionnement de GLUt                       */
/*                                              */
/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Janvier 2018                                 */

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

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

/* Constantes globales                          */

static const float jaune[] = { 1.0F,1.0F,0.0F,1.0F };
static const float rouge[] = { 1.0F,0.0F,0.0F,1.0F };
static const float vert[] = { 0.0F,1.0F,0.0F,1.0F };
static const float bleu[] = { 0.0F,0.0F,1.0F,1.0F };
static const float blanc[] = { 1.0F,1.0F,1.0F,1.0F };
static const float gris[] = { 0.5F,0.5F,0.5F,1.0F };
static const float noir[] = { 0.0F,0.0F,0.0F,1.0F };

/* Variables globales                           */

static int cFond = 0;              // Numero de la couleur de fond (0: gris, 1: blanc, 2:noir)
static float r = 0.0F;             // Angle de rotation de la scene sur elle-meme
static int anim = 1;               // Flag d'action/desactivation de l'animation
static int pMode = 1;              // Flag de switch entre modes d'affichage wireframe et fill 
static int wTx = 640;              // Resolution horizontale de la fenetre
static int wTy = 480;              // Resolution verticale de la fenetre
static int wPx = 50;               // Position horizontale de la fenetre
static int wPy = 50;               // Position verticale de la fenetre

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

void init(void) {
  const GLfloat shininess[] = { 50.0 };
  glMaterialfv(GL_FRONT,GL_SPECULAR,blanc);
  glMaterialfv(GL_FRONT,GL_SHININESS,shininess);
  glLightfv(GL_LIGHT0,GL_DIFFUSE,rouge);
  glLightfv(GL_LIGHT1,GL_DIFFUSE,jaune);
  glLightfv(GL_LIGHT2,GL_DIFFUSE,bleu);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glEnable(GL_LIGHT1);
  glEnable(GL_LIGHT2);
  glDepthFunc(GL_LESS);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_NORMALIZE);
  glEnable(GL_AUTO_NORMAL);
}

/* Scene dessinee                               */

void scene(void) {
  glPushMatrix();
  glutSolidTorus(2.7,10.0,72,180);
  glPopMatrix();
}

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

void display(void) {
  printf("D\n");
  const float *fond;
  switch (cFond) {
    case 0 :
      fond = gris;
      break;
    case 1 :
      fond = blanc;
      break;
    case 2 :
      fond = noir;
      break; }
  glClearColor(fond[0],fond[1],fond[2],fond[3]);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  const GLfloat light0_position[] = { 0.0,0.0,0.0,1.0 };
  const GLfloat light1_position[] = { -1.0,1.0,1.0,0.0 };
  const GLfloat light2_position[] = { 1.0,-1.0,1.0,0.0 };
  glLightfv(GL_LIGHT0,GL_POSITION,light0_position);
  glLightfv(GL_LIGHT1,GL_POSITION,light1_position);
  glLightfv(GL_LIGHT2,GL_POSITION,light2_position);
  glPolygonMode(GL_FRONT_AND_BACK,(pMode == 1) ? GL_FILL : GL_LINE);
  glPushMatrix();
  glRotatef(r,1.0F,2.0F,3.0F);
  scene();
  glPopMatrix();
  glFlush();
  glutSwapBuffers();
  int error = glGetError();
  if ( error != GL_NO_ERROR )
    printf("Attention erreur %d\n",error);
}

/* Fonction executee lorsqu'aucun evenement     */
/* n'est en file d'attente                      */

void idle(void) {
  printf("I\n");
  r += 1.3355F;
  glutPostRedisplay();
}

/* Fonction executee lors d'un changement       */
/* de la taille de la fenetre OpenGL            */

void reshape(int wx,int wy) {
  printf("R\n");
  wTx = wx; 
  wTy = wy; 
  glViewport(0,0,wx,wy); 
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(80.0F,(double) wx/wy,1.0,40.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  gluLookAt(0.0,0.0,20.0,0.0,0.0,0.0,0.0,1.0,0.0);
}

/* Fonction executee lors de l'appui            */
/* d'une touche alphanumerique du clavier       */

void keyboard(unsigned char key,int x,int y) {
  printf("K\n");
  switch (key) {
    case 'a' :
      { anim = !anim;
        glutIdleFunc(( anim ) ? idle : NULL); }
      break;
    case 'z' :
      { pMode = !pMode;
        glutPostRedisplay(); }
      break;
    case 'f' :
      { cFond = (cFond+1)%3;
        glutPostRedisplay(); }
      break;
    case 'F' :
      { static int full = 0;
        full = !full;
        if ( full ) {
          wTx = glutGet(GLUT_WINDOW_WIDTH);
          wTy = glutGet(GLUT_WINDOW_HEIGHT);
          wPx = glutGet(GLUT_WINDOW_X);
          wPy = glutGet(GLUT_WINDOW_Y);
          glutFullScreen(); }
          else {
          glutReshapeWindow(wTx,wTy);
          glutPositionWindow(wPx,wPy); } }
      break;
    case 0x1B :
      exit(0);
      break; }
}

/* Fonction executee lors de l'appui            */
/* d'une touche speciale du clavier :           */
/*   - touches de curseur                       */
/*   - touches de fonction                      */

void special(int specialKey,int x,int y) {
  printf("S\n");
  switch(specialKey) {
    case GLUT_KEY_UP :
      r += 1.0F;
      glutPostRedisplay();
      break;
    case GLUT_KEY_DOWN :
      r -= 1.0F;
      glutPostRedisplay();
      break; }
}

/* Fonction executee lors de l'utilisation      */
/* de la souris sur la fenetre                  */

void mouse(int buton,int state,int x,int y) {
  printf("M %d %d %d %d\n",buton,state,x,y);
}

/* Fonction executee lors du passage            */
/* de la souris sur la fenetre                  */
/* avec un boutton presse                       */

void mouseMotion(int x,int y) {
  printf("MM %d %d\n",x,y);
}

/* Fonction executee lors du passage            */
/* de la souris sur la fenetre                  */
/* sans boutton presse                          */

void passiveMouseMotion(int x,int y) {
  printf("PM %d %d\n",x,y);
}

/* Fonction principale                          */

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  glutInitWindowSize(wTx,wTy);
  glutInitWindowPosition(wPx,wPy);
  glutCreateWindow("Gestion événementielle de GLUt");
  init();
  glutSpecialFunc(special);
  glutKeyboardFunc(keyboard);
  glutMouseFunc(mouse);
  glutMotionFunc(mouseMotion);
  glutPassiveMotionFunc(passiveMouseMotion);
  glutReshapeFunc(reshape);
  glutIdleFunc((anim) ? idle : NULL);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}