public function availableHeightFrom($x, $y)
{
// get the column
$col = $this->matrix->getCol($x);
// make array start at correct y pos
for ($i = 0; $i < $y; $i++) {
array_shift($col);
}
foreach ($col as $k => $v) {
if ($v > -1) {
return $k;
}
}
// entire height available
return $this->ysize - $y;
}
