pocketmine\level\generator\populator\TallGrass::populate PHP Method

    public function populate(ChunkManager $level, $chunkX, $chunkZ, Random $random)
    {
        $this->level = $level;
        $amount = $random->nextRange(0, $this->randomAmount + 1) + $this->baseAmount;
        for ($i = 0; $i < $amount; ++$i) {
            $x = $random->nextRange($chunkX * 16, $chunkX * 16 + 15);
            $z = $random->nextRange($chunkZ * 16, $chunkZ * 16 + 15);
            $y = $this->getHighestWorkableBlock($x, $z);
            if ($y !== -1 and $this->canTallGrassStay($x, $y, $z)) {
                $this->level->setBlockIdAt($x, $y, $z, Block::TALL_GRASS);
                $this->level->setBlockDataAt($x, $y, $z, 1);
            }
        }
    }