/* Fonctionnement de GLUt                       */
/*                                              */
/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Janvier 2019                                 */

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

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

/* Variables globales                           */

static float r1 = 0.0F;            // Angle de rotation du bras du robot
static float r2 = 0.0F;            // Angle de rotation de l'avant-bras du robot
static float r3 = 0.0F;            // Angle de rotation de la pince
static float r4 = 9.0F;            // Ouverture de la pince (angle)
static int pMode = 1;              // Flag de switch entre modes d'affichage wireframe et fill 

static int wTx = 600;              // Resolution horizontale de la fenetre
static int wTy = 360;              // Resolution verticale de la fenetre
static int wPx = 50;               // Position horizontale de la fenetre
static int wPy = 50;               // Position verticale de la fenetre

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

static void init(void) {
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glDepthFunc(GL_LESS);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_NORMALIZE);
}

/* Scene dessinee                               */

#include <math.h>

#ifndef M_PI
#define M_PI 3.14159
#endif

/* Dessin d'une "boite" parallelipipedique      */

void mySolidCube(double w,double h,double d) {
  glPushMatrix();
  glScalef((float) w,(float) h,(float) d);
  glutSolidCube(1.0);
  glPopMatrix();
}

/* Dessin d'un cylindre                         */

static void mySolidCylinder(double hauteur,double rayon,int ns) {
  glPushMatrix();
  hauteur /= 2.0F;
  glBegin(GL_QUAD_STRIP);
  for( int i = 0 ; i <= ns ; i++ ){
    float a = (2*M_PI*i)/ns;
    float cs = cos(a);
    float sn = -sin(a);
    glNormal3f(cs,0.0F,sn);
    float x = rayon*cs;
    float z = rayon*sn;
    glVertex3f(x,hauteur,z);
    glVertex3f(x,-hauteur,z); }
  glEnd();
  glPopMatrix();
}

/* Une mandibule                                */

void mandibule(float r4) {
  glPushMatrix();
  glTranslatef(0.0F,0.0F,-0.65F);
  glRotatef(r4,0.0F,-1.0F,0.0F);
  glRotatef(90.0F,0.0F,1.0F,0.0F);
  glutSolidCone(0.3,1.8,12,6);
  glPopMatrix();
}

static void brasRobot(float r1,float r2,float r3,float r4) {
  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);
  mySolidCylinder(3.0,0.5,24);
  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);
  mySolidCylinder(3.0,0.4,24);
  glPopMatrix();
  glTranslatef(1.8F,0.0F,0.0F) ;
  glRotatef(r3,1.0F,0.0F,0.0F) ;
  mySolidCube(0.6,1.2,1.8) ;
  glTranslatef(0.3F,0.0F,0.0F) ;
  mandibule(r4);
  glRotatef(180.0F,1.0F,0.0F,0.0F);
  mandibule(r4);
  glPopMatrix();
}

void scene(void) {
  glPushMatrix();
  glRotatef(20.0F,1.0F,1.0F,1.0F);
  glScalef(0.2F,0.2F,0.2F);
  brasRobot(r1,r2,r3,r4);
  glPopMatrix();
}

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

static void display(void) {
  if ( pMode == 1 ) {
    glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);
    glEnable(GL_LIGHTING); }
    else {
    glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);
    glDisable(GL_LIGHTING); }
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glPushMatrix();
  scene();
  glPopMatrix();
  glFlush();
  glutSwapBuffers();
  int error = glGetError();
  if ( error != GL_NO_ERROR )
    printf("Attention erreur %d\n",error);
}

/* Fonction executee lors d'un changement       */
/* de la taille de la fenetre OpenGL            */

static void reshape(int wx,int wy) {
  wTx = wx; 
  wTy = wy; 
  glViewport(0,0,wx,wy); 
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  double ratio =(double) wx/wy; 
  if ( wx > wy ) 
    glOrtho(-ratio,ratio,-1.0,1.0,-10.0,10.0);
    else
    glOrtho(-1.0,1.0,-1.0/ratio,1.0/ratio,-10.0,10.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

/* Fonction executee lors de l'appui            */
/* d'une touche alphanumerique du clavier       */

static void keyboard(unsigned char key,int x,int y) {
  switch (key) {
    case 45 : 
      { r4 += 0.1F;
        if ( r4 > 21.0F )
          r4 = 21.0F;
          else
          glutPostRedisplay(); }
        break;
    case 43 :
      { r4 -= 0.1F;
        if ( r4 < 9.0F )
          r4 = 9.0F;
          else
          glutPostRedisplay(); }
        break;
    case ' ' :
      { pMode = !pMode;
        glutPostRedisplay(); }
      break;
    case 'f' :
    case 'F' :
      glutFullScreen();
      break;
    case 0x1B :
      exit(0);
      break; }
}

/* Fonction executee lors de l'appui            */
/* d'une touche speciale du clavier :           */
/*   - touches de curseur                       */
/*   - touches de fonction                      */

static void special(int specialKey,int x,int y) {
  switch(specialKey) {
    case GLUT_KEY_UP :
      r1 += 1.0F;
      glutPostRedisplay();
      break;
    case GLUT_KEY_DOWN :
      r1 -= 1.0F;
      glutPostRedisplay();
      break;
    case GLUT_KEY_PAGE_UP :
      r2 += 1.0F;
      glutPostRedisplay();
      break;
    case GLUT_KEY_PAGE_DOWN :
      r2 -= 1.0F;
      glutPostRedisplay();
      break;
    case GLUT_KEY_RIGHT :
      r3 += 1.0F;
      glutPostRedisplay();
      break;
    case GLUT_KEY_LEFT :
      r3 -= 1.0F;
      glutPostRedisplay();
      break; }
}

/* Fonction exécutée automatiquement            */
/* lors de l'exécution de la fonction exit()    */

static void clean(void) {
  printf("Bye\n");
}

/* Fonction principale                          */

int main(int argc,char **argv) {

  atexit(clean);

  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  glutInitWindowSize(wTx,wTy);
  glutInitWindowPosition(wPx,wPy);
  glutCreateWindow("Un bras robot avec une pince de saisie");
  init();
  glutKeyboardFunc(keyboard);
  glutSpecialFunc(special);
  glutReshapeFunc(reshape);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}