/* Auteur: Nicolas JANEY             */
/* nicolas.janey@univ-fcomte.fr      */
/* Avril 2001                        */
/* Code des extremites des segments  */
/* dans l'algorithme de clipping     */
/* de Cohen-Sutherland               */

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

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

#include "ModuleCouleurs.h"
#include "ModuleMenus.h"
#include "ModuleFont.h"
#include "ModuleFleche.h"
#include "ModuleReshape.h"

struct point {
  int x ;
  int y ; } ;

struct segment {
  point pi ;
  point pf ; } ;

struct rectangle {
  point sg ;
  point id ; } ;

static int aff = 0 ;
static segment s = { -8,6,12,-2 } ;
static int p1 = 1 ;
static int disc = 1 ;

void traceSegment(int xi,int yi,int xf,int yf,float *c) {
  glColor4fv(c) ;
  glBegin(GL_LINES) ;
  glVertex2f((float) xi,(float) yi) ;
  glVertex2f((float) xf,(float) yf) ;
  glEnd() ;
}

void pixel(int x,int y,float *c) {
  glColor4fv(c) ;
  glBegin(GL_QUADS) ;
  glVertex2f(x-0.5F,y-0.5F) ;
  glVertex2f(x-0.5F,y+0.5F) ;
  glVertex2f(x+0.5F,y+0.5F) ;
  glVertex2f(x+0.5F,y-0.5F) ;
  glEnd() ;
}

void line(int xi,int yi,int xf,int yf,float *c) {
  if ( disc ) {
    int dx,dy,i,xinc,yinc,cumul,x,y ;
    x = xi ;
    y = yi ;
    dx = xf - xi ;
    dy = yf - yi ;
    xinc = ( dx > 0 ) ? 1 : -1 ;
    yinc = ( dy > 0 ) ? 1 : -1 ;
    dx = abs(dx) ;
    dy = abs(dy) ;
    pixel(x,y,c) ;
    if ( dx > dy ) {
      cumul = dx / 2 ;
      for ( i = 1 ; i <= dx ; i++ ) {
        x += xinc ;
        cumul += dy ;
        if (cumul >= dx) {
          cumul -= dx ;
          y += yinc ; }
        pixel(x,y,c) ; } }
      else {
      cumul = dy / 2 ;
      for ( i = 1 ; i <= dy ; i++ ) {
        y += yinc ;
        cumul += dx ;
        if ( cumul >= dy ) {
          cumul -= dy ;
          x += xinc ; }
        pixel(x,y,c) ; } } }
    else {
    glColor4fv(c);
    glLineWidth(4.0);
    glBegin(GL_LINES);
    glVertex2f(xi,yi);
    glVertex2f(xf,yf);
    glEnd();
    glLineWidth(1.0); }
}

void traceRectangle(rectangle *r,float *c,float *c2) {
  line(r->id.x,-100,r->id.x,100,c2) ;
  line(-100,r->sg.y,100,r->sg.y,c2) ;
  line(r->sg.x,-100,r->sg.x,100,c2) ;
  line(-100,r->id.y,100,r->id.y,c2) ;
  line(r->id.x,r->id.y,r->id.x,r->sg.y,c) ;
  line(r->id.x,r->sg.y,r->sg.x,r->sg.y,c) ;
  line(r->id.x,r->id.y,r->sg.x,r->id.y,c) ;
  line(r->sg.x,r->id.y,r->sg.x,r->sg.y,c) ;
}

int code(point *p,rectangle *r) { 
  int c ;
  if ( p->x < r->sg.x )
    c = 1 ;
    else
    c = 0 ;
  if ( p->x > r->id.x )
    c += 2 ;
  if ( p->y < r->sg.y )
    c += 4 ;
  if ( p->y > r->id.y )
    c += 8 ;
  return(c) ;
}

int code_nul(int c) { 
  return(c == 0) ;
}

int pas1commun(int c1,int c2) { 
  return((c1&c2) == 0) ;
}

int code0(int c) { 
  return(c&1) ;
}

int code1(int c) { 
  return(c&2) ;
}

int code2(int c) { 
  return(c&4) ;
}

int code3(int c) { 
  return(c&8) ;
}

char *code(int c) {
  static char s[4];
  s[0] = ( c & 1 ) ? '1' : '0';
  s[1] = ( c & 2 ) ? '1' : '0';
  s[2] = ( c & 4 ) ? '1' : '0';
  s[3] = ( c & 8 ) ? '1' : '0';
  return(s);
}

int intersection(int ai,int bi,int af,int bf,int val) {
  int res = 0 ;
  if ( af-ai != 0 )
    res =(int) (bi +(double) (val-ai) / (af-ai) * (bf-bi)) ;
    else
    res = 32767 ;
  return(res) ;
}

void clipperSegment(rectangle *r,segment *s,float *c) {
  segment se = *s ;
  int c1,c2 ;
  point p ;
  c1 = code(&s->pi,r) ;
  c2 = code(&s->pf,r) ;
  while ( ( !code_nul(c1) || !code_nul(c2) ) && ( pas1commun(c1,c2)  ) ) {
    if ( code_nul(c1) ) {
      p = s->pi ;
      s->pi = s->pf ;
      s->pf = p ;
      c1 = c2 ; }
    if ( code0(c1) ) {
      s->pi.y = intersection(s->pi.x,s->pi.y,s->pf.x,s->pf.y,r->sg.x) ;
      s->pi.x = r->sg.x ; }
      else
      if ( code1(c1) ) {
        s->pi.y = intersection(s->pi.x,s->pi.y,s->pf.x,s->pf.y,r->id.x) ;
        s->pi.x = r->id.x ; }
        else
        if ( code2(c1) ) {
          s->pi.x = intersection(s->pi.y,s->pi.x,s->pf.y,s->pf.x,r->sg.y) ;
          s->pi.y = r->sg.y ; }
          else
          if ( code3(c1) ) {
            s->pi.x = intersection(s->pi.y,s->pi.x,s->pf.y,s->pf.x,r->id.y) ;
            s->pi.y = r->id.y ; }
    c1 = code(&s->pi,r) ;
    c2 = code(&s->pf,r) ; }
  if ( code_nul(c1) && code_nul(c2) )
    line(s->pi.x,s->pi.y,s->pf.x,s->pf.y,c) ;
  *s = se ;
}

void traceAxes(void) {
  glColor4fv(couleurVertFonce());
  glPushMatrix();
  glTranslatef(-14.0F,-9.0F,0.0F);
  flecheEnVolume(10.0F,0.0F,0.0F,1.0F,3.5F,0.3F);
  flecheEnVolume(0.0F,10.0F,0.0F,1.0F,3.5F,0.3F);
  glPopMatrix();
  placeFontCursor(-2.0F,-9.0F,0.0F);
  simpleBitmapOutput(1,REGULAR8x13,"x");
  placeFontCursor(-12.0F,3.0F,0.0F);
  simpleBitmapOutput(1,REGULAR8x13,"y");
}

float *couleurDeTrace(segment *s,rectangle *r,int *cas) {
  int ci = code(&s->pi,r);
  int cf = code(&s->pf,r);
  float *c = couleurMagenta();
  if ( ( ci == 0 ) && ( cf == 0 ) ) {
    c = couleurBleu();
    *cas = 1; }
    else
    if ( ( ci != 0 ) && ( cf != 0 ) ) {
      c = couleurMagenta();
      *cas = 4;
      if ( ( ci & cf ) != 0 ) {
        *cas = 3;
        c = couleurVertFonce(); } }
      else {
      c = couleurRouge();
      *cas = 2; }
  return(c);
}

void traceSegment(segment *s,rectangle *r) {
  int cas;
  float *c = couleurDeTrace(s,r,&cas);
  line(s->pi.x,s->pi.y,s->pf.x,s->pf.y,c) ;
  placeFontCursor((s->pf.x+s->pi.x)/2,(s->pf.y+s->pi.y)/2,0.0F);
  deplacementCursor(-15,-15,0);
  glColor4fv(c);
  simpleBitmapOutput(1,REGULAR8x13,"(%d)",cas);
}

void affichageCodes(void) {
  placeFontCursor(-29.0F,0.0F,0.0F);
  simpleBitmapOutput(1,REGULAR8x13,"1000");
  placeFontCursor(0.0F,0.0F,0.0F);
  simpleBitmapOutput(1,REGULAR8x13,"0000");
  placeFontCursor(28.0F,0.0F,0.0F);
  simpleBitmapOutput(1,REGULAR8x13,"0100");
  placeFontCursor(-29.0F,24.0F,0.0F);
  simpleBitmapOutput(1,REGULAR8x13,"1001");
  placeFontCursor(0.0F,24.0F,0.0F);
  simpleBitmapOutput(1,REGULAR8x13,"0001");
  placeFontCursor(28.0F,24.0F,0.0F);
  simpleBitmapOutput(1,REGULAR8x13,"0101");
  placeFontCursor(-29.0F,-24.0F,0.0F);
  simpleBitmapOutput(1,REGULAR8x13,"1010");
  placeFontCursor(0.0F,-24.0F,0.0F);
  simpleBitmapOutput(1,REGULAR8x13,"0010");
  placeFontCursor(28.0F,-24.0F,0.0F);
  simpleBitmapOutput(1,REGULAR8x13,"0110");
}
             
void display() {
  rectangle r = { -20,-16,19,14 } ;
  glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
  glPushMatrix();
  int ci = code(&s.pi,&r);
  int cf = code(&s.pf,&r);
  int cas;
  float *c = couleurDeTrace(&s,&r,&cas);
  switch ( aff) {
    case 0 : traceAxes();
             traceRectangle(&r,couleurBleu(),couleurJauneFonce());
             affichageCodes();
             glColor4fv(couleurNoir());
             placeFontCursor(r.id.x,r.id.y-3,0.0F);
             simpleBitmapOutput(1,REGULAR8x13,"(Xmax,Ymax)");
             placeFontCursor(r.sg.x,r.sg.y+3,0.0F);
             simpleBitmapOutput(1,REGULAR8x13,"(Xmin,Ymin)");
             break;
    case 1 : traceAxes();
             traceRectangle(&r,couleurBleu(),couleurJauneFonce());
             line(s.pi.x,s.pi.y,s.pf.x,s.pf.y,c) ;
             pixel(s.pi.x,s.pi.y,couleurNoir()) ;
             pixel(s.pf.x,s.pf.y,couleurNoir()) ;
             placeFontCursor(s.pi.x,s.pi.y,0.0F);
             deplacementCursor(0,-20,0);
             simpleBitmapOutput(1,REGULAR8x13,"(%s)",code(code(&s.pi,&r)));
             placeFontCursor(s.pf.x,s.pf.y,0.0F);
             deplacementCursor(0,20,0);
             simpleBitmapOutput(1,REGULAR8x13,"(%s)",code(code(&s.pf,&r)));
             placeFontCursor((s.pf.x+s.pi.x)/2,(s.pf.y+s.pi.y)/2,0.0F);
             deplacementCursor(10,-20,0);
             glColor4fv(c);
             simpleBitmapOutput(1,REGULAR8x13,"cas (%d)",cas);
             break ;
    case 2 : traceAxes();
             traceRectangle(&r,couleurBleu(),couleurJauneFonce());
             clipperSegment(&r,&s,c) ;
             pixel(s.pi.x,s.pi.y,couleurNoir()) ;
             pixel(s.pf.x,s.pf.y,couleurNoir()) ;
             placeFontCursor(s.pi.x,s.pi.y,0.0F);
             deplacementCursor(0,-20,0);
             simpleBitmapOutput(1,REGULAR8x13,"(%s)",code(code(&s.pi,&r)));
             placeFontCursor(s.pf.x,s.pf.y,0.0F);
             deplacementCursor(0,20,0);
             simpleBitmapOutput(1,REGULAR8x13,"(%s)",code(code(&s.pf,&r)));
             placeFontCursor((s.pf.x+s.pi.x)/2,(s.pf.y+s.pi.y)/2,0.0F);
             deplacementCursor(10,-20,0);
             glColor4fv(c);
             simpleBitmapOutput(1,REGULAR8x13,"cas (%d)",cas);
             break ;
    case 3 : { traceAxes();
               traceRectangle(&r,couleurBleu(),couleurJauneFonce());
               glColor4fv(couleurNoir());
               affichageCodes();
               segment s1 = { -8,3,12,8 } ;
               traceSegment(&s1,&r);
               segment s2 = { -6,-22,17,-10 } ;
               traceSegment(&s2,&r);
               segment s3 = { -30,11,-5,27 } ;
               traceSegment(&s3,&r);
               segment s4 = { -32,5,25,22 } ;
               traceSegment(&s4,&r);
               segment s5 = { 36,-20,31,20 } ;
               traceSegment(&s5,&r);
               segment s6 = { 3,-29,-28,-20 } ;
               traceSegment(&s6,&r); }
             break ; }
  glPopMatrix();
  glFlush();
  glutSwapBuffers() ;
}

void special(int k, int x, int y) {
  switch (k) {
    case GLUT_KEY_UP    : if ( p1 ) {
                            s.pi.y++ ;
                            if ( s.pi.y > 30 )
                              s.pi.y = 30 ; } 
                            else {
                            s.pf.y++ ;
                            if ( s.pf.y > 30 )
                              s.pf.y = 30 ; } 
                          glutPostRedisplay();
                          break;
    case GLUT_KEY_DOWN  : if ( p1 ) {
                            s.pi.y-- ;
                            if ( s.pi.y < -30 )
                              s.pi.y = -30 ; } 
                            else {
                            s.pf.y-- ;
                            if ( s.pf.y < -30 )
                              s.pf.y = -30 ; } 
                          glutPostRedisplay();
                          break;
    case GLUT_KEY_LEFT  : if ( p1 ) {
                            s.pi.x-- ;
                            if ( s.pi.x < -35 )
                              s.pi.x = -35 ; } 
                            else {
                            s.pf.x-- ;
                            if ( s.pf.x < -35 )
                              s.pf.x = -35 ; } 
                          glutPostRedisplay();
                          break;
    case GLUT_KEY_RIGHT : if ( p1 ) {
                            s.pi.x++ ;
                            if ( s.pi.x > 35 )
                              s.pi.x = 35 ; } 
                            else {
                            s.pf.x++ ;
                            if ( s.pf.x > 35 )
                              s.pf.x = 35 ; } 
                          glutPostRedisplay();
                          break; }
}

void key(unsigned char key,int x,int y) {
  switch ( key ) {
    case 0x0D : aff = (aff+1)%4 ;
                glutPostRedisplay();
                break;
    case 32   : p1 = !p1 ;
                glutPostRedisplay();
                break;
    case 'D'  : 
    case 'd'  : disc = !disc ;
                glutPostRedisplay();
                break;
    case 0x1B : exit(0);
                break; }
}

void myinit() {
  glShadeModel(GL_SMOOTH);
  glClearColor(0.8F,0.8F,0.8F,1.0F);
  setAlignement(CENTER);
}

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  glutInitWindowSize(300,240); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Code de Cohen-Sutherland"); 
  myinit(); 
  creationMenuBasique();
  setParametresOrthoBasique(-30.0,30.0,-30.0,30.0,-500.0,500.0);
  glutReshapeFunc(reshapeOrthoBasique);
  glutKeyboardFunc(key);
  glutSpecialFunc(special);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}