/* Auteur: Nicolas JANEY                     */
/* nicolas.janey@univ-fcomte.fr              */
/* Septembre 2005                            */
/* Un programme de deplacement d'une sphere  */
/* par drag and drop et de controle clavier  */
/* de la taille et de la position            */
/* de cette sphere                           */

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

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

static int lumiere = 0;
static int px = 100;
static int py = 100;
static int dx;
static int dy;
static int r = 10;
static GLfloat couleurBlanc[] = { 1.0F,1.0F,1.0F,1.0F };
static GLfloat couleurRouge[] = { 1.0F,0.0F,0.0F,1.0F };
static GLfloat couleurVert[] = { 0.0F,1.0F,0.0F,1.0F };
static GLfloat couleurBleu[] = { 0.0F,0.0F,1.0F,1.0F };
static GLfloat couleurNoir[] = { 0.0F,0.0F,0.0F,1.0F };
static int dragdrop = 0;

void init(void) {
  GLfloat mat_shininess[] = { 50.0F };
  GLfloat light0_position[] = { 1.0F,1.0F,1.0F,0.0F };
  GLfloat light1_position[] = { -1.0F,1.0F,1.0F,0.0F };
  GLfloat light2_position[] = { 1.0F,-1.0F,1.0F,0.0F };
  glMaterialfv(GL_FRONT,GL_SPECULAR,couleurBlanc);
  glMaterialfv(GL_FRONT,GL_SHININESS,mat_shininess);
  glLightfv(GL_LIGHT0,GL_DIFFUSE,couleurRouge);
  glLightfv(GL_LIGHT1,GL_DIFFUSE,couleurVert);
  glLightfv(GL_LIGHT2,GL_DIFFUSE,couleurBleu);
  glLightfv(GL_LIGHT0,GL_POSITION,light0_position);
  glLightfv(GL_LIGHT1,GL_POSITION,light1_position);
  glLightfv(GL_LIGHT2,GL_POSITION,light2_position);
  glEnable(GL_LIGHT0);
  glEnable(GL_LIGHT1);
  glEnable(GL_LIGHT2);
  glDepthFunc(GL_LESS);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_NORMALIZE);
  glEnable(GL_AUTO_NORMAL);
  glClearColor(0.0F,0.0F,0.0F,1.0F);
}

void scene(void) {
  glPushMatrix();
  glTranslatef(px,py,0.0F);
  glutSolidSphere(r,60,60);
  glPopMatrix();
}

void display(void) {
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  if ( lumiere )
    glEnable(GL_LIGHTING);
    else
    glDisable(GL_LIGHTING);
  glPushMatrix();
  scene();
  glPopMatrix();
  glFlush();
  int error = glGetError();
  if ( error != GL_NO_ERROR )
    printf("\nAttention erreur %d\n",error);
  glutSwapBuffers();
}

void souris(int bouton,int etat,int x,int y) {
  if ( etat == GLUT_DOWN )
    if ( (px-x)*(px-x)+(py-y)*(py-y) < r*r ) {
      dx = px-x;
      dy = py-y;
      dragdrop = 1; }
      else {
      px = x;
      py = y;
      glutPostRedisplay(); }
  if ( etat == GLUT_UP )
    dragdrop = 0;
}

void motion(int x,int y) {
  if ( dragdrop ) {
    px = x+dx;
    py = y+dy;
    glutPostRedisplay(); }
}

void keyboard(unsigned char key,int x,int y) {
  switch ( key ) {
    case 43     : r++;
                  glutPostRedisplay();
                  break;
    case 45     : r--;
                  if ( r < 1.0F )
                    r = 1.0F;
                  glutPostRedisplay();
                  break;
    case ' '    : lumiere = !lumiere;
                  glutPostRedisplay();
                  break;
    case 0x1B   : exit(0);
                  break; }
}

void special(int key,int x,int y) {
  switch ( key ) {
    case GLUT_KEY_RIGHT : px++;
                          glutPostRedisplay();
                          break;
    case GLUT_KEY_LEFT  : px--;
                          glutPostRedisplay();
                          break;
    case GLUT_KEY_UP    : py--;
                          glutPostRedisplay();
                          break;
    case GLUT_KEY_DOWN  : py++;
                          glutPostRedisplay();
                          break; }
}

void reshape(int w,int l) {
  glViewport(0,0,w,l);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(0,w,l,0,-100.0F,100.0F);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  glutInitWindowSize(300,300); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Controles souris et clavier"); 
  init();
  glutReshapeFunc(reshape);
  glutKeyboardFunc(keyboard);
  glutSpecialFunc(special);
  glutMouseFunc(souris);
  glutMotionFunc(motion);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}