/* Auteur: Nicolas JANEY            */
/* nicolas.janey@univ-fcomte.fr     */
/* Octobre 2006                     */
/* Gestion des lumieres en OpenGL   */

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

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

static int to = 1;
static int tl = 1;
static int cl = 1;
static float r = 0.0F;
static int anim = 1;
static float z = 1.5F;
static float rx = 0.0F;
static float rz = 0.0F;

static GLfloat bl[4] = { 1.0F,1.0F,1.0F,1.0F };
static GLfloat blanc[4] = { 3.0F,3.0F,3.0F,1.0F };
static GLfloat rouge[4] = { 3.0F,0.0F,0.0F,1.0F };
static GLfloat vert[4] = { 0.0F,3.0F,0.0F,1.0F };

void init(void) {
  glMaterialfv(GL_FRONT,GL_DIFFUSE,bl);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glEnable(GL_LIGHT1);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_NORMALIZE);
  glLightf(GL_LIGHT0,GL_CONSTANT_ATTENUATION,0);
  glLightf(GL_LIGHT0,GL_LINEAR_ATTENUATION,0);
  glLightf(GL_LIGHT0,GL_QUADRATIC_ATTENUATION,1);
  glLightf(GL_LIGHT1,GL_CONSTANT_ATTENUATION,0);
  glLightf(GL_LIGHT1,GL_LINEAR_ATTENUATION,0);
  glLightf(GL_LIGHT1,GL_QUADRATIC_ATTENUATION,1);
}

void scene(void) {
  glPushMatrix();
  if ( to ) {
    glNormal3f(0.0F,0.0F,1.0F);
    glBegin(GL_QUADS);
    for ( int i = 0 ; i < 100 ; i++ )
      for ( int j = 0 ; j < 100 ; j++ ) {
        float x = -5.0F + i*0.1F;
        float y = -5.0F + j*0.1F;
        glVertex3f(x,y,0.0F);
        glVertex3f(x+0.1F,y,0.0F);
        glVertex3f(x+0.1F,y+0.1F,0.0F);
        glVertex3f(x,y+0.1F,0.0F); }
    glEnd(); }
    else {
    glScalef(1.0F,1.0F,0.2F);
    glutSolidSphere(5.0,72,72); }
  glPopMatrix();
}

void display(void) {
  glClearColor(0.8F,0.8F,0.8F,1.0F) ;
  glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT) ;
  glPushMatrix();
  glRotatef(rx,1.0F,0.0F,0.0F);
  glRotatef(rz,0.0F,0.0F,1.0F);
  glPushMatrix();
  glRotatef(r,0.0F,0.0F,1.0F);
  GLfloat l_pos0[] = { 3.0F,0.0F,z,1.0F };
  GLfloat l_pos1[] = { -3.0F,0.0F,z,1.0F };
  GLfloat l_dir0[] = { 1.0F,0.0F,1.0F,0.0F };
  GLfloat l_dir1[] = { -1.0F,0.0F,1.0F,0.0F };
  glLightfv(GL_LIGHT0,GL_POSITION,(tl) ? l_pos0 : l_dir0);
  glLightfv(GL_LIGHT1,GL_POSITION,(tl) ? l_pos1 : l_dir1);
  glLightfv(GL_LIGHT0,GL_DIFFUSE,(cl) ? blanc : rouge);
  glLightfv(GL_LIGHT1,GL_DIFFUSE,(cl) ? blanc : vert);
  glDisable(GL_LIGHTING);
  if ( tl ) {
    glPushMatrix();
    glTranslatef(3.0F,0.0F,z);
    glColor3fv((cl) ? blanc : rouge);
    glutSolidSphere(0.2,18,18);
    glPopMatrix();
    glPushMatrix();
    glTranslatef(-3.0F,0.0F,z);
    glColor3fv((cl) ? blanc : vert);
    glutSolidSphere(0.2,18,18);
    glPopMatrix(); }
  glPopMatrix();
  glEnable(GL_LIGHTING);
  scene();
  glPopMatrix();
  glFlush();
  glutSwapBuffers();
  int error = glGetError();
  if ( error != GL_NO_ERROR )
    printf("Attention, erreur OpenGL %d\n",error);
}

void reshape(int tx,int ty) {
  glViewport(0,0,tx,ty);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(7.0,(double) tx/ty,70.0,130.0) ;
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  gluLookAt(0.0,0.0,100.0,0.0,0.0,0.0,0.0,1.0,0.0);
}

void idle(void) {
  r += 1.1F;
  glutPostRedisplay();
}

void key(unsigned char key,int x,int y) {
  switch ( key ) {
    case 'z'  : z += 0.025F ;
                glutPostRedisplay();
                break;
    case 'Z'  : z -= 0.025F ;
                glutPostRedisplay();
                break;
    case 'c'  : 
    case 'C'  : cl = !cl;
                break;
    case 'o'  : 
    case 'O'  : to = !to;
                break;
    case ' '  : anim = !anim;
                glutIdleFunc((anim) ? idle : NULL);
                break;
    case 0x0D : tl = !tl ;
                glutPostRedisplay();
                break;
    case 0x1B : exit(0); }
}

void special(int key,int x,int y) {
  switch ( key ) {
    case GLUT_KEY_UP    : rx -= 1.0F ;
                          glutPostRedisplay();
                          break;
    case GLUT_KEY_DOWN  : rx += 1.0F ;
                          glutPostRedisplay();
                          break;
    case GLUT_KEY_LEFT  : rz += 1.0F ;
                          glutPostRedisplay();
                          break;
    case GLUT_KEY_RIGHT : rz -= 1.0F ;
                          glutPostRedisplay();
                          break; }
}

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE);
  glutInitWindowSize(250,250); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Gestion lumiere");
  init(); 
  glutIdleFunc(idle);
  glutReshapeFunc(reshape);
  glutKeyboardFunc(key);
  glutSpecialFunc(special);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}