/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Octobre 2008                                 */
/* Un programme OpenGL illustrant l'utilisation */
/* de lumieres et d'un materiel                 */

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

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

/* Variables globales                           */

static int obj = 0;

static float rx = 0.0F;
static float ry = 0.0F;
static int mouvement = 0 ;
static int button = 0 ;
static int mx;
static int my;

/* Fonction executee lors de l'appui            */
/* d'une touche de la souris                    */

void mouse(int bouton,int etat,int x,int y) {
  button = bouton;
  mx = x ;
  my = y ; 
  if ( etat == GLUT_DOWN ) {
    mouvement = 1 ; }
  if ( etat == GLUT_UP ) {
    mouvement = 0 ; } 
}

/* Fonction executee lors du deplacement        */
/* de la souris devant la fenetre               */
/* avec le bouton appuye                        */

void motion(int x,int y) {
  switch ( button ) {
    case GLUT_LEFT_BUTTON :
      if ( mouvement == 1 ) {
        rx += (y-my) ;
        ry += (x-mx) ;
        mx = x; 
        my = y; 
        glutPostRedisplay(); }
        break; }
}

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

void init(void) {
  glEnable(GL_LIGHTING);
  glDepthFunc(GL_LESS);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_NORMALIZE);
  glEnable(GL_AUTO_NORMAL);
}

/* Fonction de modelisation de la scene         */

void scene(int obj) {
  glEnable(GL_LIGHTING);
  { { float c[4] = { 2.0F,0.0F,0.0F,1.0F };
      glLightfv(GL_LIGHT0,GL_DIFFUSE,c);
      glLightfv(GL_LIGHT0,GL_SPECULAR,c); }
    { float dir[4] = { 1.0F,1.0F,1.0F,0.0F };
      glLightfv(GL_LIGHT0,GL_POSITION,dir); }
    glEnable(GL_LIGHT0); }
  { { float c[4] = { 0.0F,1.0F,0.0F,1.0F };
      glLightfv(GL_LIGHT1,GL_DIFFUSE,c);
      glLightfv(GL_LIGHT1,GL_SPECULAR,c); }
    { float pos[4] = { -5.0F,-5.0F,15.0F,1.0F };
      glLightfv(GL_LIGHT1,GL_POSITION,pos); }
    glEnable(GL_LIGHT1); }
  { { float c[4] = { 0.0F,0.0F,1.0F,1.0F };
      glLightfv(GL_LIGHT2,GL_DIFFUSE,c);
      glLightfv(GL_LIGHT2,GL_SPECULAR,c); }
    { float pos[4] = { -1.0F,1.0F,15.0F,1.0F };
      glLightfv(GL_LIGHT2,GL_POSITION,pos); }
    { float dir[4] = { 1.0F,-1.0F,-15.0F };
      glLightfv(GL_LIGHT2,GL_SPOT_DIRECTION,dir); }
    glLightf(GL_LIGHT2,GL_SPOT_CUTOFF,8.594374F);
    glLightf(GL_LIGHT2,GL_SPOT_EXPONENT,0.0F);
    glEnable(GL_LIGHT2); }
  { float t[4] = { 0.6F,0.2F,0.8F,1.0F };
    glMaterialfv(GL_FRONT_AND_BACK,GL_DIFFUSE,t); }
  { float t[4] = { 0.0F,0.0F,0.0F,1.0F };
    glMaterialfv(GL_FRONT_AND_BACK,GL_AMBIENT,t); }
  { float t[4] = { 0.4F,0.8F,0.2F,1.0F };
    glMaterialfv(GL_FRONT_AND_BACK,GL_SPECULAR,t); }
  { float t[4] = { 0.0F,0.0F,0.0F,1.0F };
    glMaterialfv(GL_FRONT_AND_BACK,GL_EMISSION,t); }
  glPushMatrix();
  switch (obj) {
    case 0 :
      { float t[4] = { 6.40F };
        glMaterialfv(GL_FRONT_AND_BACK,GL_SHININESS,t); }
      glRotatef(57.295826F,1.10F,-1.0F,0.0F);
      glutSolidCube(6.0);
      break;
    case 1 :
      { float t[4] = { 32.0F };
        glMaterialfv(GL_FRONT_AND_BACK,GL_SHININESS,t); }
      glutSolidSphere(4.0,180,180);
      break; }
  glPopMatrix();
}

/* 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) ;
  /* Affichage de la scene                      */
  glPushMatrix();
  glRotatef(rx,1.0F,0.0F,0.0F);
  glRotatef(ry,0.0F,1.0F,0.0F);
  scene(obj);
  glPopMatrix();
  glFlush();
  glutSwapBuffers();
  int error = glGetError();
  if ( error != GL_NO_ERROR )
    printf("Attention, erreur OpenGL %d\n",error);
}

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

void reshape(int tx,int ty) {
  glViewport(0,0,tx,ty);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  float ratio =(float) tx/ty;
  gluPerspective(6.302541F,ratio,1.0,1000.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glTranslatef(-0.0F,-0.0F,-100.0F);
}

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

void keyboard(unsigned char key,int x,int y) {
  switch ( key ) {
    case ' '  : obj = (obj+1)%2;
                glutPostRedisplay();
                break;
    case 0x1B : exit(0); }
}

/* Fonction principale                          */

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE|GLUT_DEPTH);
  glutInitWindowSize(250,250); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Lumieres et materiel");
  init();
  glutMouseFunc(mouse);
  glutMotionFunc(motion);
  glutReshapeFunc(reshape);
  glutKeyboardFunc(keyboard);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}