/* Auteur: Nicolas JANEY                 */
/* nicolas.janey@univ-fcomte.fr          */
/* Mars 2002                             */
/* Rasterisation d'un segment de droite  */
/* sur un ecran bitmap                   */

#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 "ModuleReshape.h"

struct coord2D {
  double x;
  double y; } ;

struct segment {
  coord2D pi;
  coord2D pf; } ;

int aff = 0;
static segment seg = { { 5,3 },{ 35,16 } };

void pixel(int x, int y) {
  glBegin(GL_QUADS) ;
  glVertex2i(x,y) ;
  glVertex2i(x+1,y) ;
  glVertex2i(x+1,y+1) ;
  glVertex2i(x,y+1) ;
  glEnd() ;
}

void lignePixels(int xi,int yi,int xf,int yf) {
  int i,cumul ;
  int x = xi ;
  int y = yi ;
  int dx = xf - xi ;
  int dy = yf - yi ;
  int xinc = ( dx > 0 ) ? 1 : -1 ;
  int yinc = ( dy > 0 ) ? 1 : -1 ;
  dx = abs(dx) ;
  dy = abs(dy) ;
  pixel(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 ; }
      pixel(x,y) ; } }
    else {
    cumul = dy / 2 ;
    for ( i = 1 ; i <= dy ; i++ ) {
      y += yinc ;
      cumul += dx ;
      if ( cumul >= dy ) {
        cumul -= dy ;
        x += xinc ; }
      pixel(x,y) ; } }
}

void dessineSegment(float *c,segment *s) {
  glColor4fv(c) ;
  glLineWidth(3.0) ;
  glBegin(GL_LINES) ;
  glVertex2d(s->pi.x+0.5,s->pi.y+0.5);
  glVertex2d(s->pf.x+0.5,s->pf.y+0.5);
  glEnd() ;
  glLineWidth(1.0) ;
}

void dessineQuadrillage(float *c) {
  int i;
  glColor4fv(c) ;
  glBegin(GL_LINES);
  for ( i = 1 ; i < 20 ; i++ ) {
    glVertex2d(1.0,i);
    glVertex2d(39.0,i); }
  for ( i = 1 ; i < 40 ; i++ ) {
    glVertex2d(i,1.0);
    glVertex2d(i,19.0); }
  glEnd() ;
}

void display() {
  glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
  glPushMatrix();
  switch (aff) {
    case 0 : dessineSegment(couleurRouge(),&seg) ;
             break ;
    case 1 : dessineQuadrillage(couleurBleu()) ;
             dessineSegment(couleurRouge(),&seg) ;
             break ; }
  glPopMatrix();
  glFlush();
  glutSwapBuffers() ;
}

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

void myinit() {
  glClearColor(0.8F,0.8F,0.8F,1.0F);
}

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  glutInitWindowSize(320,160); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Rasterisation d'un segment"); 
  myinit(); 
  creationMenuBasique();
  setParametresOrthoBasique(0.0,20.0,0.0,20.0,-50.0,50.0);
  glutReshapeFunc(reshapeOrthoBasique);
  glutKeyboardFunc(key);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}