protected function buildOctogonShape($squareSize) { $s = $squareSize; $c = $s * 0.33; $sMinusC = $s - $c; return "{$c},0,{$sMinusC},0,{$s},{$c},{$s},{$sMinusC},{$sMinusC},{$s},{$c},{$s},0,{$sMinusC},0,{$c},{$c},0"; }