/* Auteur: Nicolas JANEY                   */
/* nicolas.janey@univ-fcomte.fr            */
/* Octobre 2007                            */
/* Materiel et lumieres sur des spheres    */

#include <stdio.h>

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

/* Variables globales                           */

static int mode = 0;
static int disc = 120;
static float py = 0.0F;
static float angle = 0.0F;
static const float blanc[] = { 1.0F,1.0F,1.0F,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 gris[] = { 0.25F,0.25F,0.25F,1.0F };
static const float noir[] = { 0.0F,0.0F,0.0F,1.0F };

/* Variables globales de gestion                */
/* de l'interactivite clavier et souris         */

static int clic = 0;
static int mx;
static int my;
static float rx = 0.0F;
static float ry = 0.0F;
static float zoom = 1.0F;

/* Fonction d'affichage d'une eventuelle        */
/* erreur OpenGL                                */

static void checkError(int line) {
  GLenum err = glGetError();
  if (err) {
    printf("GL Error %s (0x%x) at line %d\n",
           gluErrorString(err), (int) err, line); }
}

/* Fonction d'initialisation de certains        */
/* parametres de l'environnement OpenGL         */
/* et allocation des tableaux de stockage       */
/* des informations relatives aux particules    */

void init(void) {
  glClearColor(0.0F,0.0F,0.0F,1.0F);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glEnable(GL_LIGHT1);
  glEnable(GL_LIGHT2);
  glEnable(GL_AUTO_NORMAL);
  glEnable(GL_NORMALIZE);
  glDepthFunc(GL_LESS);
  glEnable(GL_DEPTH_TEST);
  glMaterialf(GL_FRONT,GL_SHININESS,32.0F);
}

void configurationLumieres() {
  { GLfloat l_pos[] = { 1.0F,0.0F,0.0F,0.0F };
    glLightfv(GL_LIGHT0,GL_POSITION,l_pos);
    glLightfv(GL_LIGHT0,GL_DIFFUSE,blanc);
    glLightfv(GL_LIGHT0,GL_SPECULAR,blanc);
    glLightfv(GL_LIGHT0,GL_AMBIENT,(mode == 0) ? noir : gris); }
  { GLfloat l_pos[] = { 0.0F,py,0.0F,1.0F };
    glLightfv(GL_LIGHT1,GL_POSITION,l_pos);
    glLightfv(GL_LIGHT1,GL_DIFFUSE,blanc);
    glLightfv(GL_LIGHT1,GL_SPECULAR,blanc);
    glLightfv(GL_LIGHT1,GL_AMBIENT,(mode == 0) ? noir : gris); }
  { GLfloat l_pos[] = { 0.0F,0.0F,10.0F,1.0F };
    GLfloat l_dir[] = { 0.0F,0.0F,-1.0F,0.0F };
    glLightfv(GL_LIGHT2,GL_POSITION,l_pos);
    glLightfv(GL_LIGHT2,GL_DIFFUSE,blanc);
    glLightfv(GL_LIGHT2,GL_SPECULAR,blanc);
    glLightfv(GL_LIGHT2,GL_AMBIENT,(mode == 0) ? noir : gris);
    { glPushMatrix();
      glRotatef(angle,0.0F,1.0F,0.0F);
      glLightfv(GL_LIGHT2,GL_SPOT_DIRECTION,l_dir);
      glPopMatrix(); }
    glLightf(GL_LIGHT2,GL_SPOT_CUTOFF,25); }
}

void configurationMateriel() {
  switch (mode) {
    case 0 : glMaterialfv(GL_FRONT,GL_DIFFUSE,rouge);
             glMaterialfv(GL_FRONT,GL_SPECULAR,vert);
             glMaterialfv(GL_FRONT,GL_AMBIENT,noir);
             glMaterialfv(GL_FRONT,GL_EMISSION,noir);
             break;
    case 1 : glMaterialfv(GL_FRONT,GL_DIFFUSE,vert);
             glMaterialfv(GL_FRONT,GL_SPECULAR,bleu);
             glMaterialfv(GL_FRONT,GL_AMBIENT,gris);
             glMaterialfv(GL_FRONT,GL_EMISSION,gris);
             break;
    case 2 : glMaterialfv(GL_FRONT,GL_DIFFUSE,vert);
             glMaterialfv(GL_FRONT,GL_SPECULAR,noir);
             glMaterialfv(GL_FRONT,GL_AMBIENT,noir);
             glMaterialfv(GL_FRONT,GL_EMISSION,noir);
             break;
    case 3 : glMaterialfv(GL_FRONT,GL_DIFFUSE,noir);
             glMaterialfv(GL_FRONT,GL_SPECULAR,bleu);
             glMaterialfv(GL_FRONT,GL_AMBIENT,noir);
             glMaterialfv(GL_FRONT,GL_EMISSION,noir);
             break;
    case 4 : glMaterialfv(GL_FRONT,GL_DIFFUSE,noir);
             glMaterialfv(GL_FRONT,GL_SPECULAR,noir);
             glMaterialfv(GL_FRONT,GL_AMBIENT,gris);
             glMaterialfv(GL_FRONT,GL_EMISSION,noir);
             break;
    case 5 : glMaterialfv(GL_FRONT,GL_DIFFUSE,noir);
             glMaterialfv(GL_FRONT,GL_SPECULAR,noir);
             glMaterialfv(GL_FRONT,GL_AMBIENT,noir);
             glMaterialfv(GL_FRONT,GL_EMISSION,gris);
             break; }
}

void scene(void) {
  glPushMatrix();
  glutSolidSphere(5.0,disc,disc);
  glTranslatef(10.0F,0.0F,0.0F);
  glutSolidSphere(2.0,disc,disc);
  glPopMatrix();
}

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

void display(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);
  glScalef(zoom,zoom,zoom);
  configurationLumieres();
  configurationMateriel();
  scene();
  glPopMatrix();
  glFlush();
  glutSwapBuffers();
  checkError(__LINE__);
}

/* 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();
  gluPerspective(40,(double) tx/ty,0.1,50.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  gluLookAt(3.5F,0.0F,20.0F,3.5F,0.0F,0.0F,0.0F,1.0F,0.0F);
}

/* Fonction executee lorsqu'aucun evenement     */
/* n'est en attente de gestion                  */

static void idle1(void) {
  static float dy = 0.1F;
  py += dy;
  if ( ( py <= -10.0F ) || ( py >= 10.0F ) )
    dy = -dy;
  glutPostRedisplay();
}

/* Fonction executee lorsqu'aucun evenement     */
/* n'est en attente de gestion                  */

static void idle2(void) {
  idle1();
  angle += 1.0F;
  glutPostRedisplay();
}

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

void key(unsigned char key,int x,int y) {
  switch ( key ) {
    case 43   : disc++;
                glutPostRedisplay();
                break;
    case 45   : disc--;
                if ( disc < 3 )
                  disc = 3;
                glutPostRedisplay();
                break;
    case 'r'  :
    case 'R'  : angle = 0.0F;
                py = 0.0F;
                glutPostRedisplay();
                break;
    case 0x20 : { static int anim = 0;
                  anim = (anim+1)%3;
                  switch (anim) {
                    case 0 : glutIdleFunc(NULL);
                             break;
                    case 1 : glutIdleFunc(idle1);
                             break;
                    case 2 : glutIdleFunc(idle2);
                             break; } }
                break;
    case 0x0D : mode = (mode+1)%6;
                glutPostRedisplay();
                break;
    case 0x1B : exit(0);
                break; }
}

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

void special(int key,int x,int y) {
  switch ( key ) {
    case GLUT_KEY_UP      : zoom *= 0.99F;
                            glutPostRedisplay();
                            break;
    case GLUT_KEY_DOWN    : zoom /= 0.99F;
                            glutPostRedisplay();
                            break; }
}

/* Fonction executee lors d'un clic de souris   */
/* dans la fenetre                              */

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

/* Fonction executee lors d'un deplacement      */
/* de la souris sur la fenetre                  */
/* avec un bouton appuye                        */

void motion(int x,int y) {
  if ( clic ) {
    ry += (x-mx);
    rx += (y-my);
    mx = x;
    my = y;
    glutPostRedisplay(); }
}

/* Fonction principale                          */

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  glutInitWindowSize(260,180); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Materiel et lumieres");
  init(); 
  glutReshapeFunc(reshape);
  glutKeyboardFunc(key);
  glutSpecialFunc(special);
  glutMotionFunc(motion);
  glutMouseFunc(mouse);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}