/* Placage de texture sur un carre              */
/*                                              */
/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Novembre 2011                                */

#include <stdio.h>
#include <math.h>
#include <stdlib.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 rx = 0.0F;
static float ry = 0.0F;
static float rz = 0.0F;
static int objet = 0;
static int aff = 1;

GLbyte *lireImageRaw(int tx,int ty,char *filename) {
  GLbyte *img = NULL;
  FILE *file = fopen(filename,"rb");
  if ( file ) {
    img =(GLbyte *) calloc(tx*ty*3,sizeof(GLbyte));
    fread(img,1,tx*ty*3,file);
    fclose(file); }
  return(img);
}

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

void keyboard(unsigned char key,int x,int y) {
  switch ( key ) {
    case 0x20 :
      aff = (aff+1)%2;
      glutPostRedisplay(); 
      break;
    case 0x0D :
      objet = (objet+1)%2;
      glutPostRedisplay(); 
      break;
    case 0x1B :
      exit(0); 
      break; }
}

/* Fonction executee lors de l'appui            */
/* d'une touche de curseur ou d'une touche      */
/* page up ou page down                         */

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

/* 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);
  glEnable(GL_CULL_FACE);
  GLbyte *image = lireImageRaw(16,16,"Damier.raw");
  if ( image ) {
    glPixelStorei(GL_UNPACK_ALIGNMENT,1); 
    glTexImage2D(GL_TEXTURE_2D,0,3,16,16,0,GL_RGB,GL_UNSIGNED_BYTE,image);
    free(image);
    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); 
    glEnable(GL_TEXTURE_2D); }
}

/* Scene dessinee                               */

void scene(void) {
  glPushMatrix();
  glBegin(GL_QUADS);
  glNormal3f(0.0F,0.0F,1.0F);
  glTexCoord2f(0.0F,0.0F);
  glVertex3f(-2.0F,-2.0F,0.0F);
  glTexCoord2f(1.0F,0.0F);
  glVertex3f(2.0F,-2.0F,0.0F);
  glTexCoord2f(1.0F,1.0F);
  glVertex3f(2.0F,2.0F,0.0F);
  glTexCoord2f(0.0F,1.0F);
  glVertex3f(-2.0F,2.0F,0.0F);
  glEnd();
  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);
  glPolygonMode(GL_FRONT_AND_BACK,(aff) ? GL_FILL : GL_LINE);
  glPushMatrix();
  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  */

void reshape(int x,int y) {
  glViewport(0,0,x,y); 
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(20.0F,(float) x/y,1.0,50.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  gluLookAt(0.0,10.0,15.0,0.0,0.0,0.0,0.0,1.0,0.0);
}

/* Fonction principale                          */

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  glutInitWindowSize(300,300); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Un carre texturé"); 
  init();
  glutKeyboardFunc(keyboard);
  glutSpecialFunc(special);
  glutReshapeFunc(reshape);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}