/* Remplissage 2D d'une facette triangulaire    */
/*                                              */
/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Septembre 2012                               */

#include <stdlib.h>
#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 jaune[]   = { 1.0F,1.0F,0.0F,1.0F };
static const float magenta[] = { 1.0F,0.0F,1.0F,1.0F };
static const float rouge[]   = { 1.0F,0.0F,0.0F,1.0F };
static const float vert[]    = { 0.0F,0.7F,0.0F,1.0F };
static const float bleu[]    = { 0.0F,0.0F,1.0F,1.0F };

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

/* Affichage des coordonnees des pixels         */
/* allumes lors du trace d'un segment de droite */
/* par algorithme de Bresenham                  */

static void affichageSegment(int *px,int *py) {
  int dx,dy,i,xinc,yinc,cumul,x,y;
  x = px[0];
  y = py[0];
  dx = px[1] - px[0];
  dy = py[1] - py[0];
  xinc = ( dx > 0 ) ? 1 : -1;
  yinc = ( dy > 0 ) ? 1 : -1;
  dx = abs(dx);
  dy = abs(dy);
  printf("%3d %3d\n",x,y);
  if ( dx > dy ) {
    cumul = dx / 2;
    for ( i = 1 ; i <= dx ; i++ ) {
      x += xinc;
      cumul += dy;
      if ( cumul >= dx ) {
        cumul -= dx;
        y += yinc; }
      printf("%3d %3d\n",x,y); } }
    else {
    cumul = dy / 2;
    for ( i = 1 ; i <= dy ; i++ ) {
      y += yinc;
      cumul += dx;
      if ( cumul >= dy ) {
        cumul -= dy;
        x += xinc; }
      printf("%3d %3d\n",x,y); } }
}

static int mx[2] = { -1,-1 };
static int my[2] = { -1,-1 };
static int nb = 0;
static int bt = 0;

/* Fonction appelee lors d'un clic de souris    */

static void mouse(int bouton,int etat,int x,int y) {
  if ( bouton == GLUT_LEFT_BUTTON ) {
    mx[nb%2] = x;
    my[nb%2] = y;
    bt = 1;
    if ( etat == GLUT_UP ) {
      printf("%4d %4d\n",x,y);
      bt = 0;
      nb++; }
    glutPostRedisplay(); }
  if ( bouton == GLUT_RIGHT_BUTTON ) {
    if ( etat == GLUT_UP ) {
      if ( mx[1] != -1 )
        affichageSegment(mx,my); } }
}

/* Fonction appelee lors d'un deplacement       */
/* de souris bouton appuye                      */

static void motion(int x,int y) {
  if ( bt ) {
    mx[nb%2] = x;
    my[nb%2] = y;
    printf("%4d %4d\n",x,y);
    glutPostRedisplay(); }
}

/* Scene dessinee                               */

static int aff = 1;

static void scene(void) {
  glPushMatrix();
  if ( mx[0] != -1 ) {
    glPushMatrix();
    glTranslatef(mx[0],my[0],0.0F);
    glutSolidSphere(10.0,36,36);
    glPopMatrix(); }
  if ( mx[1] != -1 ) {
    glPushMatrix();
    glTranslatef(mx[1],my[1],0.0F);
    glutSolidSphere(10.0,36,36);
    glPopMatrix();
    if ( aff ) {
      glBegin(GL_LINES);
      glVertex2f(mx[0],my[0]);
      glVertex2f(mx[1],my[1]);
      glEnd(); } }
  glPopMatrix();
}

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

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

static void display(void) {
  glClearColor(0.8F,0.8F,0.8F,1.0F);
  glClear(GL_COLOR_BUFFER_BIT);
  glPushMatrix();
  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 x,int y) {
  glViewport(0,0,x,y); 
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(0.0,x,y,0.0,-100.0,100.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

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

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

/* Fonction principale                          */

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE);
  glutInitWindowSize(350,350); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Gestion de la souris");
  glutMouseFunc(mouse);
  glutMotionFunc(motion);
  glutKeyboardFunc(keyboard);
  glutReshapeFunc(reshape);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}