#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <time.h>
#include "paulslib.h"
#include "bitmaplib.h"

/*
   Very basic (brute force) 2D DLA code
   Seed in the center, random points added round the rim
   Written for simplicity not speed or elegance
   Paul Bourke

   The two usual ways of improving performance are
   - Keep an internal state (2D array of occupied sites) rather than checking the image each time.
   - Only introduce points at a radius just bigger than the current structure.
   - Don't let points wander too far away.
   All of the above will dramatically improve speed.

   Note this does not implement the so called "stickiness" algorithm.
*/

// Image size, radius of "world"
#define R 1000

// Number of points to introduce
#define N 50000

int main(int argc,char **argv)
{
   int i,j,n,ix,iy,ixnew,iynew;
   int found;
   int counter = 0;
   time_t secs;
   double theta;
   FILE *fptr;
   BITMAP4 *image = NULL,white = {255,255,255,0},black = {0,0,0,0};
   BITMAP4 v;
   char fname[64];

   // Create and initialise the final image
   image = Create_Bitmap(R,R);
   Erase_Bitmap(image,R,R,white);
   Draw_Pixel(image,R,R,R/2,R/2,black);

   // Set the random number seeds based upon the current time
   time(&secs);
   srand((int)secs);
   srand48((int)secs);

   for (n=0;n<N;n++) {
      theta = drand48() * TWOPI;
      ix = R/2 + 0.5 * (R-2) * cos(theta);
      iy = R/2 + 0.5 * (R-2) * sin(theta);
      fprintf(stderr,"Seed: %d %d %d\n",n,ix,iy);

      // Repeat until we hit another pixel
      for (;;) {

         // Move in a random direction
         ixnew = ix + (rand() % 3) - 1;
         if (ixnew > 0 && ixnew < R-1)
            ix = ixnew;
         iynew = iy + (rand() % 3) - 1;
         if (iynew > 0 && iynew < R-1)
            iy = iynew;

         // Have we struck an existing point?
         found = FALSE;
         for (i=-1;i<=1;i++) {
            for (j=-1;j<=1;j++) {
               v = Get_Pixel(image,R,R,ix+i,iy+j);
               if (v.r < 128) {
                  found = TRUE;
                  break;
               }
            }
            if (found)
               break;
         }
         if (found)
            break;
      }

      Draw_Pixel(image,R,R,ix,iy,black);

      // Save intermediate images
      if (n > 0 && n % (N/10) == 0) {
         sprintf(fname,"dla_%02d.tga",counter++);
         if ((fptr = fopen(fname,"w")) == NULL) {
            fprintf(stderr,"Failed to open output file\n");
         } else {
            Write_Bitmap(fptr,image,R,R,12);
            fclose(fptr);
         }
      }
   }

   // Write the image to a TGA file
   if ((fptr = fopen("dla.tga","w")) == NULL) {
      fprintf(stderr,"Failed to open output file\n");
   } else {
      Write_Bitmap(fptr,image,R,R,12);
      fclose(fptr);
   }

   exit(0);
}