/* Placage de 6 textures sur les faces          */
/* d'un cube                                    */
/*                                              */
/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Fevrier 2021                                 */

#include <stdio.h>
#include <stdlib.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 int affichage = 1;
static int texture = 1;
static int animation = 0;

static float rx = 0.0F;
static float ry = 0.0F;
static float rz = 0.0F;

//////////////////////////////////////////////////

#include "PNG/ChargePngFile.h"

static unsigned int textureID[6] = { 0,0,0,0,0,0 };

/* Fonction de chargement d'une texture         */
/* a partir d'un fichier image au format png    */
/* filename : le nom du fichier                 */
/* textureID : le handle de la texture          */

static void chargementTexture(char *filename,unsigned int textureID) {
  glBindTexture(GL_TEXTURE_2D,textureID);
  glPixelStorei(GL_UNPACK_ALIGNMENT,1); 
  { int rx;
    int ry;
    unsigned char *img = chargeImagePng(filename,&rx,&ry);
    if ( img ) {
      glTexImage2D(GL_TEXTURE_2D,0,3,rx,ry,0,GL_RGB,GL_UNSIGNED_BYTE,img);
      free(img);
      printf("Texture chargée %d : %s\n",textureID,filename); }
      else {
      printf("Texture non chargée\n"); } }
  glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_REPEAT); 
  glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_REPEAT);
  glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST); 
  glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST); 
}

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

static void init(void) {
  glClearColor(0.25F,0.25F,0.25F,1.0F);
  glLightfv(GL_LIGHT0,GL_DIFFUSE,blanc);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glDepthFunc(GL_LESS);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_NORMALIZE);
  glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,1);
  glGenTextures(6,textureID);
  chargementTexture("Emoji1.png",textureID[0]);
  chargementTexture("Emoji2.png",textureID[1]);
  chargementTexture("Emoji3.png",textureID[2]);
  chargementTexture("Emoji4.png",textureID[3]);
  chargementTexture("Emoji5.png",textureID[4]);
  chargementTexture("Emoji6.png",textureID[5]);
}

/* Modelisation geometrique d'un cube           */
/* avec placage de textures sur chacune         */
/* de ses faces                                 */
/* ct : la taille du cube                       */
/* texID : le tableau des 6 handles de texture  */
/*         a utiliser                           */

static void mySolidCube(double ct,unsigned int *texID) {
  float c =(float) ct/2.0F;
  /* Activation premiere texture                */
  glBindTexture(GL_TEXTURE_2D,texID[0]);
  glBegin(GL_QUADS);
  glNormal3f(0.0F,0.0F,-1.0F);
  glTexCoord2f(0.0F,0.0F);
  glVertex3f( c, c,-c);
  glTexCoord2f(0.0F,1.0F);
  glVertex3f( c,-c,-c);
  glTexCoord2f(1.0F,1.0F);
  glVertex3f(-c,-c,-c);
  glTexCoord2f(1.0F,0.0F);
  glVertex3f(-c, c,-c);
  glEnd();
  /* Activation deuxieme texture                */
  glBindTexture(GL_TEXTURE_2D,texID[1]);
  glBegin(GL_QUADS);
  glNormal3f(0.0F,0.0F,1.0F);
  glTexCoord2f(0.0F,0.0F);
  glVertex3f(-c,-c, c);
  glTexCoord2f(1.0F,0.0F);
  glVertex3f( c,-c, c);
  glTexCoord2f(1.0F,1.0F);
  glVertex3f( c, c, c);
  glTexCoord2f(0.0F,1.0F);
  glVertex3f(-c, c, c);
  glEnd();
  /* Activation troisieme texture               */
  glBindTexture(GL_TEXTURE_2D,texID[2]);
  glBegin(GL_QUADS);
  glNormal3f(-1.0F,0.0F,0.0F);
  glTexCoord2f(0.0F,0.0F);
  glVertex3f(-c, c,-c);
  glTexCoord2f(0.0F,1.0F);
  glVertex3f(-c,-c,-c);
  glTexCoord2f(1.0F,1.0F);
  glVertex3f(-c,-c, c);
  glTexCoord2f(1.0F,0.0F);
  glVertex3f(-c, c, c);
  glEnd();
  /* Activation quatrieme texture               */
  glBindTexture(GL_TEXTURE_2D,texID[3]);
  glBegin(GL_QUADS);
  glNormal3f(1.0F,0.0F,0.0F);
  glTexCoord2f(0.0F,0.0F);
  glVertex3f( c, c, c);
  glTexCoord2f(0.0F,1.0F);
  glVertex3f( c,-c, c);
  glTexCoord2f(1.0F,1.0F);
  glVertex3f( c,-c,-c);
  glTexCoord2f(1.0F,0.0F);
  glVertex3f( c, c,-c);
  glEnd();
  /* Activation cinquieme texture               */
  glBindTexture(GL_TEXTURE_2D,texID[4]);
  glBegin(GL_QUADS);
  glNormal3f(0.0F,-1.0F,0.0F);
  glTexCoord2f(0.0F,0.0F);
  glVertex3f(-c,-c, c);
  glTexCoord2f(0.0F,1.0F);
  glVertex3f(-c,-c,-c);
  glTexCoord2f(1.0F,1.0F);
  glVertex3f( c,-c,-c);
  glTexCoord2f(1.0F,0.0F);
  glVertex3f( c,-c, c);
  glEnd();
  /* Activation sixieme texture                 */
  glBindTexture(GL_TEXTURE_2D,texID[5]);
  glBegin(GL_QUADS);
  glNormal3f(0.0F,1.0F,0.0F);
  glTexCoord2f(0.0F,0.0F);
  glVertex3f( c, c, c);
  glTexCoord2f(0.0F,1.0F);
  glVertex3f( c, c,-c);
  glTexCoord2f(1.0F,1.0F);
  glVertex3f(-c, c,-c);
  glTexCoord2f(1.0F,0.0F);
  glVertex3f(-c, c, c);
  glEnd();
}

/* Scene dessinee                               */

static void scene(void) {
  glPushMatrix();
  mySolidCube(5.0,textureID);
  glPopMatrix();
}

/* Desallocation des textures                   */

static void clean(void) {
  for ( int i = 0 ; i < 6 ; i++ )
    if ( textureID[i] != 0 )
      glDeleteTextures(1,&textureID[i]);
}

//////////////////////////////////////////////////

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

static void display(void) {
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  const GLfloat light0_position[] = { 0.0,0.0,10.0,1.0 };
  glPolygonMode(GL_FRONT_AND_BACK,(affichage) ? GL_FILL : GL_LINE);
  if ( texture ) 
    glEnable(GL_TEXTURE_2D);
    else
    glDisable(GL_TEXTURE_2D);
  glPushMatrix();
  glLightfv(GL_LIGHT0,GL_POSITION,light0_position);
  gluLookAt(0.0,0.0,10.0,0.0,0.0,0.0,0.0,1.0,0.0);
  glRotatef(rx,1.0F,0.0F,0.0F);
  glRotatef(ry,0.0F,1.0F,0.0F);
  glRotatef(rz,0.0F,0.0F,1.0F);
  scene();
  glPopMatrix();
  glFlush();
  glutSwapBuffers();
  int error = glGetError();
  if ( error != GL_NO_ERROR )
    printf("Erreur OpenGL: %d\n",error);
}

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

static void reshape(int tx,int ty) {
  glViewport(0,0,tx,ty); 
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  double ratio =(double) tx/ty;
  if ( ratio >= 1.0 )
    gluPerspective(50.0,ratio,0.01,200.0);
    else
    gluPerspective(50.0/ratio,ratio,0.01,200.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

/* Fonction executee en tache de fond           */

static void idle(void) {
  rx += 0.7F;
  ry += 0.5F;
  rz += 0.3F;
  glutPostRedisplay();
}

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

static void keyboard(unsigned char key,int x,int y) {
  switch ( key ) {
    case 'a' :
      animation = !animation;
      glutIdleFunc(( animation ) ? idle : NULL);
      break;
    case 0x0D :
      affichage = (affichage+1)%2;
      glutPostRedisplay(); 
      break;
    case 0x20 :
      texture = (texture+1)%2;
      glutPostRedisplay(); 
      break;
    case 0x1B :
      exit(0); 
      break; }
}

/* Fonction principale                          */

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

  atexit(clean);

  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  glutInitWindowSize(480,360); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Plaçage de textures"); 
  init();
  glutKeyboardFunc(keyboard);
  glutReshapeFunc(reshape);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}