/* Clipping de Cohen-Sutherland                 */
/*                                              */
/* Auteur: Nicolas JANEY                        */
/* nicolas.janey@univ-fcomte.fr                 */
/* Septembre 2011                               */

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

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

#include "Rectangle2D.h"
#include "Position2D.h"
#include "Segment2D.h"

/* Variables et constantes globales             */

static int scn = 0;

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

void init(void) {
}

/* Scene dessinee                               */

static void drawRectangle(Rectangle2D *r) {
  glPushMatrix();
  glBegin(GL_LINE_LOOP);
  glVertex2d(r->ig->c[0],r->ig->c[1]);
  glVertex2d(r->sd->c[0],r->ig->c[1]);
  glVertex2d(r->sd->c[0],r->sd->c[1]);
  glVertex2d(r->ig->c[0],r->sd->c[1]);
  glEnd();
  glPopMatrix();
}

static void drawSegment(Segment2D *s) {
  glPushMatrix();
  glBegin(GL_LINES);
  glVertex2d(s->pi->c[0]+0.4999,s->pi->c[1]+0.4999);
  glVertex2d(s->pf->c[0]+0.4999,s->pf->c[1]+0.4999);
  glEnd();
  glPopMatrix();
}

void sceneAvecClipping(void) {
  Position2D *p1 = new Position2D(100.0,80.0);
  Position2D *p2 = new Position2D(300.0,220.0);
  Rectangle2D *r = new Rectangle2D(p1,p2);
  delete(p1);
  delete(p2);
  glPushMatrix();
  glColor3f(1.0F,1.0F,1.0F);
  drawRectangle(r);
  glPopMatrix();
  for ( int i = 0 ; i < 100 ; i++ ) {
    Position2D *pi = new Position2D(rand()%400,rand()%300);
    Position2D *pf = new Position2D(rand()%400,rand()%300);
    Segment2D *s = new Segment2D(pi,pf);
    delete(pi);
    delete(pf);
    glColor3f(1.0F,0.0F,0.0F);
    if ( s->clip(r) )
      drawSegment(s);
    delete(s); }
  delete(r);
}

void sceneSansClipping(void) {
  Position2D *p1 = new Position2D(100.0,80.0);
  Position2D *p2 = new Position2D(300.0,220.0);
  Rectangle2D *r = new Rectangle2D(p1,p2);
  delete(p1);
  delete(p2);
  glPushMatrix();
  glColor3f(1.0F,1.0F,1.0F);
  drawRectangle(r);
  glPopMatrix();
  for ( int i = 0 ; i < 100 ; i++ ) {
    Position2D *pi = new Position2D(rand()%400,rand()%300);
    Position2D *pf = new Position2D(rand()%400,rand()%300);
    Segment2D *s = new Segment2D(pi,pf);
    delete(pi);
    delete(pf);
    glColor3f(1.0F,0.0F,0.0F);
    drawSegment(s);
    delete(s); }
  delete(r);
}

/* Fonction executee lors d'un changement       */
/* de la taille de la fenetre OpenGL            */

void reshape(int tx,int ty) {
  glViewport(0,0,tx,ty); 
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(0,tx,0,ty,-20.0,20.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

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

void display(void) {
  glClearColor(0.5F,0.5F,0.5F,0.5F);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  srand(1);
  glPushMatrix();
  if ( scn )
    sceneAvecClipping();
    else 
    sceneSansClipping();
  glPopMatrix();
  glFlush();
  glutSwapBuffers();
  int error = glGetError();
  if ( error != GL_NO_ERROR )
    printf("Erreur : %d\n",error);
}

/* Fonction executee lors de l'appui            */
/* d'une touche alphanumerique du clavier       */

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

/* Fonction principale                          */

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  glutInitWindowSize(400,300); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Clipping de Cohen-Sutherland"); 
  init();
  glutKeyboardFunc(keyboard);
  glutReshapeFunc(reshape);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}