Experimental Field Lines

/* Chris M. Thomasson Field Lines c99
_________________________________________________*/

#include <stdio.h>
#include <assert.h>
#include <complex.h>
#include <tgmath.h>


void
ct_iterate_pixel(
     FILE* fout,
     double complex z,
     double complex c,
     unsigned int imax
){
     //printf("z = %.1f%+.1fi\n", creal(z), cimag(z));

     double o = 999999999999.0;
     double g = 9999999.0;

     double complex zp = z;

     for (unsigned int i = 0; i < imax; ++i)
     {
         z = z * z + c;

         double dis = cabs(z);

         o = (o < dis) ? o : dis;

         //if (cabs(z) > 256.0)
         if (creal(z) / creal(zp) > g &&
             cimag(z) / cimag(zp) > g)
         {
             double sum = (i + 1) * (i + .01) * 123U;
             unsigned int red = sum;
             fprintf(fout, "%u %u %u  ", red % 256U, 0, 0);
             return;
         }

         zp = z;
     }

     //double sum = fabs(creal(z)) + fabs(cimag(z) + o) * 1223456U;
     double sum = (o + .01) * 256;
     unsigned int red = ((unsigned int)sum) % 256U;

     fprintf(fout, "%u %u %u  ", 0, red % 256U, 0);

     return;
}


void
ct_iterate_plane(
     FILE* fout,
     unsigned int width,
     unsigned int height,
     unsigned int imax
){
     assert(width > 1 && height > 1);

     char const ppm_head[] =
         "P3\n"
         "# Chris M. Thomasson FFE Cipher Renderer ver:0.0.0.0 (pre-alpha)";

     printf("fout:%p\n", (void*)fout);

     fprintf(fout, "%s\n%u %u\n%u\n", ppm_head, width, height, 255);

     double xstep = 4.0 / (width - 1.0);
     double ystep = 4.0 / (height - 1.0);

     for (unsigned int y = 0; y < height; ++y)
     {
         for (unsigned int x = 0; x < width; ++x)
         {
             double complex z = (-2.0 + x * xstep) + I * (2.0 - y * ystep);

             //printf("(%u, %u):z = %.1f%+.1fi\n", x, y, creal(z), cimag(z));

             ct_iterate_pixel(fout, z, z, imax);
         }

         printf("processing y:%u of %u\r", y + 1, height);
     }

     printf("\nrender complete!\n");
}


int main(void)
{
     FILE* fout = fopen("ct_ffe_cipher.ppm", "w");
     assert(fout != NULL);

     ct_iterate_plane(fout, 1024, 1024, 128);

     fclose(fout);

     return 0;
}