start print from Z layer

start_from_z

<?php

$reading = fopen('1.gcode', 'r');
$writing = fopen('1.tmp', 'w');

$replaced = false;
$i = 0;
echo '<pre>';
while (!feof($reading)) {
    $i++;
    $line = fgets($reading);
    preg_match_all('/(G.*F.*\sZ(\d+(?:\.[0-9]{1,2})?))/', $line, $matches);
    if ($matches[0]) {
        $line = str_replace($matches[2][0], round(($matches[2][0] - 33.48) . '0',3), $line);
        $replaced = true;
    }
  fputs($writing, $line);
}
fclose($reading);
fclose($writing);
// might as well not overwrite the file if we didn't replace anything
if ($replaced) {
    rename('1.tmp', 'gcode');
} else {
    unlink('1.tmp');
}