/* Une scene OpenGL simple : un bras robot      */
/*                                              */
/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Septembre 2009                               */

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

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

/* Variables et constantes globales             */

static const float blanc[] = { 1.0F,1.0F,1.0F,1.0F };
static const float gris[]  = { 0.7F,0.7F,0.7F,1.0F };

static float r1 = 30.0F;
static float r2 = -50.0F;
static int objet = 0;

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

void init(void) {
  const GLfloat mat_shininess[] = { 50.0 };
  glMaterialfv(GL_FRONT,GL_SPECULAR,blanc);
  glMaterialfv(GL_FRONT,GL_SHININESS,mat_shininess);
  glLightfv(GL_LIGHT0,GL_DIFFUSE,gris);
  glLightfv(GL_LIGHT1,GL_DIFFUSE,gris);
  glLightfv(GL_LIGHT2,GL_DIFFUSE,gris);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glEnable(GL_LIGHT1);
  glEnable(GL_LIGHT2);
  glDepthFunc(GL_LESS);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_NORMALIZE);
  glEnable(GL_AUTO_NORMAL);
}

/* Scene dessinee avec des cubes                */

void scene5() {
  glPushMatrix();
  glRotatef(r1,0.0F,1.0F,0.0F);
  glTranslatef(1.5F,0.0F,0.0F);
  glPushMatrix();
  glScalef(3.0F,1.0F,1.0F);
  glutSolidCube(1.0);
  glPopMatrix();
  glTranslatef(1.5F,0.0F,0.0F);
  glRotatef(r2,0.0F,1.0F,0.0F);
  glTranslatef(1.5F,0.0F,0.0F);
  glPushMatrix();
  glScalef(3.0F,0.8F,0.8F);
  glutSolidCube(1.0);
  glPopMatrix();
  glPopMatrix();
}

/* Scene dessinee avec des cylindres            */

void cylindre(double h,double r,int n,int m) {
  glPushMatrix();
  glRotatef(90.0F,1.0F,0.0F,0.0F);
  glTranslatef(0.0F,0.0F,-h/2);
  GLUquadricObj *qobj = gluNewQuadric();
  gluQuadricDrawStyle(qobj,GLU_FILL);
  gluCylinder(qobj,r,r,h,n,m);
  gluDeleteQuadric(qobj);  
  glPopMatrix();
}

void scene6() {
  glPushMatrix();
  glRotatef(r1,0.0F,1.0F,0.0F);
  glTranslatef(1.5F,0.0F,0.0F);
  glPushMatrix();
  glRotatef(90.0F,0.0F,0.0F,1.0F);
  cylindre(3.0,0.5,12,12);
  glPopMatrix();
  glTranslatef(1.5F,0.0F,0.0F);
  glRotatef(r2,0.0F,1.0F,0.0F);
  glTranslatef(1.5F,0.0F,0.0F);
  glPushMatrix();
  glRotatef(90.0F,0.0F,0.0F,1.0F);
  cylindre(3.0,0.4,12,12);
  glPopMatrix();
  glPopMatrix();
}

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

void display(void) {
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  const GLfloat light0_position[] = { 1.0,1.0,1.0,0.0 };
  const GLfloat light1_position[] = { -1.0,1.0,1.0,0.0 };
  const GLfloat light2_position[] = { 1.0,-1.0,1.0,0.0 };
  glLightfv(GL_LIGHT0,GL_POSITION,light0_position);
  glLightfv(GL_LIGHT1,GL_POSITION,light1_position);
  glLightfv(GL_LIGHT2,GL_POSITION,light2_position);
  glPushMatrix();
  switch (objet) {
    case 0 :
      scene5();
      break;
    case 1 :
      scene6();
      break; }
  glPopMatrix();
  glFlush();
  glutSwapBuffers();
  int error = glGetError();
  if ( error != GL_NO_ERROR )
    printf("Erreur OpenGL\n",error);
}

/* Fonction executee lors d'un changement       */
/* de la taille de la fenetre OpenGL            */
/* -> Ajustement de la camera de visualisation  */

void reshape(int x,int y) {
  glViewport(0,0,x,y); 
  glMatrixMode(GL_PROJECTION) ;
  glLoadIdentity() ;
  gluPerspective(15.0F,(float) x/y,1.0,50.0) ;
  glMatrixMode(GL_MODELVIEW) ;
  glLoadIdentity() ;
  gluLookAt(2.5,10.0,15.0,2.5,0.5,0.0,0.0,1.0,0.0);
}

/* Fonction executee lors de la frappe          */
/* d'une touche du clavier                      */
void keyboard(unsigned char key,int x,int y) {
  switch ( key ) {
    case 0x0D :
      objet = (objet+1)%2;
      glutPostRedisplay(); 
      break;
    case 0x1B :
      exit(0); 
      break; }
}

/* Fonction principale                          */

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  glutInitWindowSize(450,300); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Bras robot partiel"); 
  init();
  glutKeyboardFunc(keyboard);
  glutReshapeFunc(reshape);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}