ÉCRITURE DE LABYRINTHE

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

#define CTOI(C)   (*(int*)&C) 
#define ABS(n) (n<=0)?-n:n


int complement(unsigned int nb)
{
    switch(nb%4)
    {
        case 0 : return 0;
        default : return 4-nb%4;
    }       
}    

void set(unsigned char *data, 
         unsigned long i,
         unsigned long j,
         unsigned char r,
         unsigned char g,
         unsigned char b,
         unsigned long ligne_size)
{
     data[j*ligne_size+i*3]=b;
     data[j*ligne_size+i*3+1]=g;
     data[j*ligne_size+i*3+2]=r;
}    


void draw_line(unsigned char *data,    // les deux points doivent être sur une même "ligne"
               unsigned long x1,       //  et dessine un couloir
               unsigned long y1,
               unsigned long x2,
               unsigned long y2,
               unsigned long ligne_size)
{
    //printf("%d %d %d %d\n",x1,y1,x2,y2);
    unsigned long i;
    if (x1==x2)
        {
             if (y1>y2)
             for (i=y2; i<y1; i++)
                 set(data,x1,i,1,67,188,ligne_size);
             else
             for (i=y1; i<y2; i++)
                 set(data,x1,i,1,67,188,ligne_size);           
        }
    else    // y1==y2
        {
             if (x1>x2)
             for (i=x2; i<x1; i++)
                 set(data,i,y1,1,67,188,ligne_size);
             else
             for (i=x1; i<x2; i++)
                 set(data,i,y1,1,67,188,ligne_size);            
        }    
}    


void draw_labyrinthe(unsigned char *data, 
                     unsigned long departx,
                     unsigned long departy,
                     unsigned long coin1x,
                     unsigned long coin1y,
                     unsigned long coin2x,
                     unsigned long coin2y,
                     unsigned long ligne_size)
{
    // condition d'arrêt
    if ((ABS(coin1x-coin2x)>3) && (ABS(coin1y-coin2y)>3))
      { 
        // on se déplace au milieu de la zone    
        draw_line(data, departx, departy, (int)((coin1x+coin2x)/2), (int)((coin1y+coin2y)/2),ligne_size);
        if (departy==(int)((coin1y+coin2y)/2))
           {
               draw_labyrinthe(data,(int)((coin1x+coin2x)/2), (int)((coin1y+coin2y)/2), coin1x, coin1y, coin2x, (int)((coin1y+coin2y)/2), ligne_size);  //bas
               draw_labyrinthe(data,(int)((coin1x+coin2x)/2), (int)((coin1y+coin2y)/2), coin1x, (int)((coin1y+coin2y)/2), coin2x, coin2y, ligne_size);  // haut
           }    
        else
           {
               draw_labyrinthe(data, (int)((coin1x+coin2x)/2), (int)((coin1y+coin2y)/2), coin1x, coin1y, (int)((coin1x+coin2x)/2), coin2y, ligne_size);  //gauche
               draw_labyrinthe(data, (int)((coin1x+coin2x)/2), (int)((coin1y+coin2y)/2), (int)((coin1x+coin2x)/2), coin1y, coin2x, coin2y, ligne_size);  //droite
           }    
      }
}    

put_exit(unsigned char *data, unsigned long largeur, unsigned long hauteur,unsigned long ligne_size)
{
    unsigned long x=rand()%largeur;
    while ((data[(hauteur-2)*ligne_size+x*3]!=1) && 
          (data[(hauteur-2)*ligne_size+x*3+1]!=67) && 
          (data[(hauteur-2)*ligne_size+x*3+2]!=188))
          x++;
    //printf("%d %d", x, hauteur-1);
    set(data, x, hauteur-1, 1,67,188, ligne_size);
}    

int main(int argc, char **argv)
{
    unsigned int largeur=2000, hauteur=2000;
    
    FILE *fichier=fopen("labyrinthe.bmp", "w");
    unsigned char header[54]={0};
    unsigned long ligne_size=largeur*3+complement(largeur*3);
    unsigned long datasize=hauteur* ligne_size;
    //printf("%ld", datasize);
   
    header[0]='B';
    header[1]='M';
    CTOI(header[2])=54+datasize;
    CTOI(header[10])=54;
    CTOI(header[14])=40;
    CTOI(header[18])=largeur;
    CTOI(header[22])=hauteur;
    CTOI(header[26])=1;
    CTOI(header[28])=24;
    CTOI(header[34])=datasize;
    fwrite(&header,1,54,fichier);
    
    char *data=(char*)calloc(datasize,1);
    if (data==NULL) return 1;
    
    /* on colorie tout en 2,150,20*/
    unsigned int i,j;
    for (j=0; j<hauteur; j++)
      for (i=0; i<largeur; i++)
         set(data, i,j,2,150,20, ligne_size);
    
    srand(2);
    draw_labyrinthe(data, (int)largeur/2, 1, 0, hauteur, largeur, 1, ligne_size);
    
    set(data, (int)largeur/2, 1, 1,100,188, ligne_size);
    put_exit(data,largeur,hauteur, ligne_size);
    
    fwrite(data, 1, largeur*hauteur*3, fichier); 
    free(data);
    
    fclose(fichier);
    return 0;   
}