/* Auteur: Nicolas JANEY                */
/* nicolas.janey@univ-fcomte.fr         */
/* Avril 2001                           */
/* Une facette texturee avec un damier  */

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

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

/* Variables globales                           */

static int dm = 0;

static float rx = 0.0F;
static float ry = 0.0F;
static int mouvement = 0;
static int button = 0;
static int mx;
static int my;

void damier1() {
  static GLubyte image[] = { 0x00,0x00,0x00,0xFF,0xFF,0xFF,
                             0xFF,0xFF,0xFF,0x00,0x00,0x00 };
  glPixelStorei(GL_UNPACK_ALIGNMENT,1);
  glTexImage2D(GL_TEXTURE_2D,0,3,2,2,0,GL_RGB,GL_UNSIGNED_BYTE,image);
  glEnable(GL_TEXTURE_2D);
  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); 
}

void damier2() {
  static GLubyte image[] = { 0xFF,0x00,0x00,0xFF,0xFF,0x00,
                             0x00,0xFF,0xFF,0x00,0x00,0xFF };
  glPixelStorei(GL_UNPACK_ALIGNMENT,1);
  glTexImage2D(GL_TEXTURE_2D,0,3,2,2,0,GL_RGB,GL_UNSIGNED_BYTE,image);
  glEnable(GL_TEXTURE_2D);
  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); 
}

void display() {
  static int odm = -1;
  if ( dm != odm ) {
    odm = dm;
    switch (dm) {
      case 0 :
        damier1();
        break;
      case 1 :
        damier2();
        break; } }
  glClear(GL_DEPTH_BUFFER_BIT|GL_COLOR_BUFFER_BIT);
  glPushMatrix();
  glRotatef(rx,1.0F,0.0F,0.0F);
  glRotatef(ry,0.0F,1.0F,0.0F);
  glBegin(GL_POLYGON);
  glTexCoord2f(0.0f,0.0f);
  glVertex3f(-4.0f,-4.0f,0.0f);
  glTexCoord2f(0.0f,1.0f);
  glVertex3f(-4.0f,4.0f,0.0f);
  glTexCoord2f(1.0f,1.0f);
  glVertex3f(4.0f,4.0f,0.0f);
  glTexCoord2f(1.0f,0.0f);
  glVertex3f(4.0f,-4.0f,0.0f);
  glEnd();
  glPopMatrix();
  glutSwapBuffers();
}

void init() {
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glEnable(GL_AUTO_NORMAL);
  glEnable(GL_NORMALIZE);
}

/* Fonction executee lors de l'appui            */
/* d'une touche de la souris                    */

void mouse(int bouton,int etat,int x,int y) {
  button = bouton;
  mx = x;
  my = y; 
  if ( etat == GLUT_DOWN ) {
    mouvement = 1; }
  if ( etat == GLUT_UP ) {
    mouvement = 0; } 
}

/* Fonction executee lors du deplacement        */
/* de la souris devant la fenetre               */
/* avec le bouton appuye                        */

void motion(int x,int y) {
  switch ( button ) {
    case GLUT_LEFT_BUTTON :
      if ( mouvement == 1 ) {
        rx += (y-my);
        ry += (x-mx);
        mx = x; 
        my = y; 
        glutPostRedisplay(); }
        break; }
}

/* 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) {
  glViewport(0,0,tx,ty);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  float ratio =(float) tx/ty;
  gluPerspective(6.302541F,ratio,1.0,1000.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glTranslatef(-0.0F,-0.0F,-100.0F);
}

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

void keyboard(unsigned char key,int x,int y) {
  switch ( key ) {
    case 0x0D : dm = !dm;
                glutPostRedisplay();
                break;
    case 0x1B : exit(0); }
}

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitWindowSize(250,250);
  glutInitWindowPosition(50,50);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  int f1 = glutCreateWindow("Facette texturee");
  init();
  glutDisplayFunc(display);
  glutMouseFunc(mouse);
  glutMotionFunc(motion);
  glutReshapeFunc(reshape);
  glutKeyboardFunc(keyboard);
  glutMainLoop();
  return(0);
}