/* Simple backend for a Logo like tortoise drawer. */

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

static const int WIDTH = 10;
static const int HEIGHT = 10;

static FILE*
start_gnuplot() {
  FILE* output;
  int pipes[2];
  pid_t pid;

  pipe(pipes);
  pid = fork();

  if (!pid) {
    dup2 (pipes[0], STDIN_FILENO);
    execlp ("gnuplot", NULL);
    return; /* Not reached. */
  }

  output = fdopen(pipes[1], "w");

  fprintf (output, "set multiplot\n");
  fprintf (output, "set parametric\n");
  fprintf (output, "set xrange [-%d:%d]\n", WIDTH, WIDTH);
  fprintf (output, "set yrange [-%d:%d]\n", HEIGHT, HEIGHT);
  fprintf (output, "set size ratio -1\n");
  fprintf (output, "unset xtics\n");
  fprintf (output, "unset ytics\n");
  fflush (output);

  return output;
 }

static FILE* global_output;

int main(int argc, char *argv[]) {
  global_output = start_gnuplot();

  return EXIT_SUCCESS;
}