/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Octobre 2008                                 */
/* Un programme OpenGL de placement             */
/* d'une camera au sein d'une scene             */

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

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

/* Variables globales                           */

static double dist;

/* Fonction de modelisation de la scene         */

void element(GLfloat *c1,GLfloat *c2,GLfloat *c3) {
  glPushMatrix();
  glMaterialfv(GL_FRONT,GL_DIFFUSE,c1);
  glutSolidTorus(0.75,10.0,90,90);
  glPushMatrix();
  glMaterialfv(GL_FRONT,GL_DIFFUSE,c2);
  glTranslatef(6.0F,0.0F,0.0F);
  glScalef(12.0F,1.5F,1.5F);
  glutSolidCube(1.0);
  glPopMatrix();
  glPushMatrix();
  glMaterialfv(GL_FRONT,GL_DIFFUSE,c3);
  glTranslatef(-6.0F,0.0F,0.0F);
  glScalef(12.0F,1.5F,1.5F);
  glutSolidCube(1.0);
  glPopMatrix();
  glPopMatrix();
}

void scene(void) {
  const GLfloat l_pos0[] = { 1.0F,1.0F,1.0F,0.0F };
  const GLfloat l_pos1[] = { -1.0F,1.0F,1.0F,0.0F };
  const GLfloat blanc[4] = { 1.0F,1.0F,1.0F,1.0F };
  const GLfloat gris[4] = { 0.6F,0.6F,0.6F,1.0F };
  const GLfloat rouge[4] = { 1.0F,0.0F,0.0F,1.0F };
  const GLfloat vert[4] = { 0.0F,1.0F,0.0F,1.0F };
  const GLfloat bleu[4] = { 0.0F,0.0F,1.0F,1.0F };
  const GLfloat jaune[4] = { 1.0F,1.0F,0.0F,1.0F };
  const GLfloat cyan[4] = { 0.0F,1.0F,1.0F,1.0F };
  const GLfloat magenta[4] = { 1.0F,0.0F,1.0F,1.0F };
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glEnable(GL_LIGHT1);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_NORMALIZE);
  glLightfv(GL_LIGHT0,GL_POSITION,l_pos0);
  glLightfv(GL_LIGHT1,GL_POSITION,l_pos1);
  glLightfv(GL_LIGHT0,GL_DIFFUSE,gris);
  glLightfv(GL_LIGHT1,GL_DIFFUSE,gris);
  glPushMatrix();
  element((GLfloat *) blanc,(GLfloat *) rouge,(GLfloat *) jaune);
  glPopMatrix();
  glPushMatrix();
  glRotatef(90.0F,1.0F,0.0F,0.0F);
  glRotatef(90.0F,0.0F,0.0F,1.0F);
  element((GLfloat *) blanc,(GLfloat *) vert,(GLfloat *) cyan);
  glPopMatrix();
  glPushMatrix();
  glRotatef(90.0F,0.0F,1.0F,0.0F);
  glRotatef(90.0F,0.0F,0.0F,1.0F);
  element((GLfloat *) blanc,(GLfloat *) bleu,(GLfloat *) magenta);
  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();
  glTranslatef(-100.0F,-100.0F,-100.0F);
  scene();
  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) {
  dist = 100.0*sqrt(3.0);
  glViewport(0,0,tx,ty);
  double ratio =(double) tx/ty;
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(8.0,ratio,dist-15.0,dist+15.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glRotatef(-54.76F,-1.0,1.0,0.0);
}

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

void keyboard(unsigned char key,int x,int y) {
  switch ( key ) {
    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("Placement de camera");
  glutReshapeFunc(reshape);
  glutKeyboardFunc(keyboard);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}