/* Clipping de Cohen-Sutherland                 */
/* d'un segment de droite vis a vis             */                      
/* d'un quadrilatere quelconque                 */
/*                                              */
/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Decembre 2012                                */

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

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

#include "Position2D.h"
#include "Direction2D.h"
#include "Segment2D.h"
#include "Quadrilatere2D.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 };

static int zoom = 11;
static int aff = 1;

static Position2D *q1 = NULL;
static Position2D *q2 = NULL;
static Position2D *q3 = NULL;
static Position2D *q4 = NULL;
static Position2D *s1 = NULL;
static Position2D *s2 = NULL;

static void clean(void) {
  if ( q1 ) {
    delete(q1);
    q1 = NULL; }
  if ( q2 ) {
    delete(q2);
    q2 = NULL; }
  if ( q3 ) {
    delete(q3);
    q3 = NULL; }
  if ( q4 ) {
    delete(q4);
    q4 = NULL; }
  if ( s1 ) {
    delete(s1);
    s1 = NULL; }
  if ( s2 ) {
    delete(s2);
    s2 = NULL; }
}

/* Scene dessinee                               */

static void fond(void) {
  glColor3fv(bleu);
  int tx = (glutGet(GLUT_WINDOW_WIDTH)+(zoom-1))/zoom;
  int ty = (glutGet(GLUT_WINDOW_HEIGHT)+(zoom-1))/zoom;
  for ( int x = 0 ; x <= tx ; x++ )
    for ( int y = 0 ; y <= ty ; y++ ) {
      glBegin(GL_LINE_LOOP);
      glVertex2i(x*zoom,y*zoom);
      glVertex2i(x*zoom+(zoom-1),y*zoom);
      glVertex2i(x*zoom+(zoom-1),y*zoom+(zoom-1));
      glVertex2i(x*zoom,y*zoom+(zoom-1));
      glEnd(); }
}

static void scene(void) {
  glColor4fv(jaune);
  Quadrilatere2D *q = new Quadrilatere2D(q1,q2,q3,q4);
  q->draw(zoom);
  Segment2D *s = new Segment2D(s1,s2);
  glColor4fv(rouge);
  s->draw(zoom);
  if ( q->clip(s) ) {
    glColor4fv(vert);
    s->draw(zoom); }
  delete(s);
  delete(q);
}

static void scene2(void) {
  glColor4fv(jaune);
  Quadrilatere2D *q = new Quadrilatere2D(q1,q2,q3,q4);
  q->zoom(zoom);
  q->drawGL();
  Segment2D *s = new Segment2D(s1,s2);
  s->zoom(zoom);
  glColor4fv(rouge);
  s->drawGL();
  if ( q->clip(s) ) {
    glColor4fv(vert);
    s->drawGL(); }
  delete(s);
  delete(q);
}

/* 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();
  switch(aff) {
    case 0 :
      fond();
      scene();
      break;
    case 1 :
      scene2();
      break; }
  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,0.0,y,-1000.0,1000.0);
  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 43 :
      zoom++;
      glutPostRedisplay(); 
      break;
    case 45 :
      zoom--;
      if ( zoom == 0 )
        zoom = 1;
      glutPostRedisplay(); 
      break;
    case 0x20 :
      s1->c[0] = 2+rand()%40;
      s1->c[1] = 2+rand()%24;
      s2->c[0] = 2+rand()%40;
      s2->c[1] = 2+rand()%24;
      glutPostRedisplay(); 
      break;
    case 0x0D :
      aff = !aff;
      glutPostRedisplay(); 
      break;
    case 0x1B :
      clean();
      exit(0); 
      break; }
}

/* Fonction principale                          */

int main(int argc,char **argv) {
  atexit(clean);
  q1 = new Position2D(31.0,11.0);
  q2 = new Position2D(32.0,24.0);
  q3 = new Position2D(11.0,17.0);
  q4 = new Position2D(14.0,9.0);
  s1 = new Position2D( 9.0, 3.0);
  s2 = new Position2D(29.0,26.0);
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE);
  glutInitWindowSize(480,320); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Clipping de Cohen-Sutherland"); 
  glutKeyboardFunc(keyboard);
  glutReshapeFunc(reshape);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}