diff --git a/src/pocketmine/entity/Living.php b/src/pocketmine/entity/Living.php
index ef1ad6f9c..6b39edd69 100644
--- a/src/pocketmine/entity/Living.php
+++ b/src/pocketmine/entity/Living.php
@@ -22,6 +22,7 @@
 namespace pocketmine\entity;
 
 
+use pocketmine\block\Block;
 use pocketmine\event\entity\EntityDamageByEntityEvent;
 use pocketmine\event\entity\EntityDamageEvent;
 use pocketmine\event\entity\EntityDeathEvent;
@@ -32,6 +33,7 @@ use pocketmine\math\Vector3;
 use pocketmine\nbt\tag\Short;
 use pocketmine\network\protocol\EntityEventPacket;
 use pocketmine\Server;
+use pocketmine\utils\BlockIterator;
 
 abstract class Living extends Entity implements Damageable{
 
@@ -168,4 +170,63 @@ abstract class Living extends Entity implements Damageable{
 	public function getDrops(){
 		return [];
 	}
+
+	/**
+	 * @param int   $maxDistance
+	 * @param int   $maxLength
+	 * @param array $transparent
+	 *
+	 * @return Block[]
+	 */
+	public function getLineOfSight($maxDistance, $maxLength = 0, array $transparent = []){
+		if($maxDistance > 120){
+			$maxDistance = 120;
+		}
+
+		if(count($transparent) === 0){
+			$transparent = null;
+		}
+
+		$blocks = [];
+		$itr = new BlockIterator($this->level, $this->getPosition(), $this->getEyeHeight(), $maxDistance);
+
+		while($itr->valid()){
+			$itr->next();
+			$block = $itr->current();
+			$blocks[] = $block;
+
+			if($maxLength !== 0 and count($blocks) > $maxLength){
+				array_shift($blocks);
+			}
+
+			$id = $block->getID();
+
+			if($transparent === null){
+				if($id !== 0){
+					break;
+				}
+			}else{
+				if(!isset($transparent[$id])){
+					break;
+				}
+			}
+		}
+
+		return $blocks;
+	}
+
+	/**
+	 * @param int   $maxDistance
+	 * @param array $transparent
+	 *
+	 * @return Block
+	 */
+	public function getTargetBlock($maxDistance, array $transparent = []){
+		$block = array_shift($this->getLineOfSight($maxDistance, 1, $transparent));
+		if($block instanceof Block){
+			return $block;
+		}
+
+		return null;
+	}
 }
diff --git a/src/pocketmine/math/Vector3.php b/src/pocketmine/math/Vector3.php
index f22924ab9..dcea259c7 100644
--- a/src/pocketmine/math/Vector3.php
+++ b/src/pocketmine/math/Vector3.php
@@ -26,6 +26,14 @@ namespace pocketmine\math;
  * If this class is modified, remember to modify the PHP C extension.
  */
 class Vector3{
+
+	const SIDE_DOWN = 0;
+	const SIDE_UP = 1;
+	const SIDE_NORTH = 2;
+	const SIDE_SOUTH = 3;
+	const SIDE_WEST = 4;
+	const SIDE_EAST = 5;
+
 	public $x;
 	public $y;
 	public $z;
@@ -136,23 +144,42 @@ class Vector3{
 
 	public function getSide($side, $step = 1){
 		switch((int) $side){
-			case 0:
+			case self::SIDE_DOWN:
 				return new Vector3($this->x, $this->y - $step, $this->z);
-			case 1:
+			case self::SIDE_UP:
 				return new Vector3($this->x, $this->y + $step, $this->z);
-			case 2:
+			case self::SIDE_NORTH:
 				return new Vector3($this->x, $this->y, $this->z - $step);
-			case 3:
+			case self::SIDE_SOUTH:
 				return new Vector3($this->x, $this->y, $this->z + $step);
-			case 4:
+			case self::SIDE_WEST:
 				return new Vector3($this->x - $step, $this->y, $this->z);
-			case 5:
+			case self::SIDE_EAST:
 				return new Vector3($this->x + $step, $this->y, $this->z);
 			default:
 				return $this;
 		}
 	}
 
+	public static function getOppositeSide($side){
+		switch((int) $side){
+			case self::SIDE_DOWN:
+				return self::SIDE_UP;
+			case self::SIDE_UP:
+				return self::SIDE_DOWN;
+			case self::SIDE_NORTH:
+				return self::SIDE_SOUTH;
+			case self::SIDE_SOUTH:
+				return self::SIDE_NORTH;
+			case self::SIDE_WEST:
+				return self::SIDE_EAST;
+			case self::SIDE_EAST:
+				return self::SIDE_WEST;
+			default:
+				return -1;
+		}
+	}
+
 	public function distance(Vector3 $pos){
 		return sqrt($this->distanceSquared($pos));
 	}
diff --git a/src/pocketmine/utils/BlockIterator.php b/src/pocketmine/utils/BlockIterator.php
new file mode 100644
index 000000000..2e2197829
--- /dev/null
+++ b/src/pocketmine/utils/BlockIterator.php
@@ -0,0 +1,290 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+namespace pocketmine\utils;
+
+use pocketmine\level\Level;
+use pocketmine\block\Block;
+use pocketmine\math\Vector3;
+
+/**
+ * This class performs ray tracing and iterates along blocks on a line
+ */
+class BlockIterator implements \Iterator{
+
+	/** @var Level */
+	private $level;
+	private $maxDistance;
+
+	private static $gridSize = 16777216; //1 << 24
+
+	private $end = false;
+
+	/** @var Block[] */
+	private $blockQueue = [null, null, null];
+	private $currentBlock = 0;
+	private $currentDistance = 0;
+	private $maxDistanceInt = 0;
+
+	private $secondError;
+	private $thirdError;
+
+	private $secondStep;
+	private $thirdStep;
+
+	private $mainFace;
+	private $secondFace;
+	private $thirdFace;
+
+	public function __construct(Level $level, Vector3 $start, Vector3 $direction, $yOffset = 0, $maxDistance = 0){
+		$this->level = $level;
+		$this->maxDistance = (int) $maxDistance;
+
+		$startClone = clone $start;
+		$startClone->y += $yOffset;
+
+		$this->currentDistance = 0;
+
+		$mainDirection = 0;
+		$secondDirection = 0;
+		$thirdDirection = 0;
+
+		$mainPosition = 0;
+		$secondPosition = 0;
+		$thirdPosition = 0;
+
+		$startBlock = $this->level->getBlock($startClone->floor());
+
+		if($this->getXLength($direction) > $mainDirection){
+			$this->mainFace = $this->getXFace($direction);
+			$mainDirection = $this->getXLength($direction);
+			$mainPosition = $this->getXPosition($direction, $startClone, $startBlock);
+
+			$this->secondFace = $this->getYFace($direction);
+			$secondDirection = $this->getYLength($direction);
+			$secondPosition = $this->getYPosition($direction, $startClone, $startBlock);
+
+			$this->thirdFace = $this->getZFace($direction);
+			$thirdDirection = $this->getZLength($direction);
+			$thirdPosition = $this->getZPosition($direction, $startClone, $startBlock);
+		}
+		if($this->getYLength($direction) > $mainDirection){
+			$this->mainFace = $this->getYFace($direction);
+			$mainDirection = $this->getYLength($direction);
+			$mainPosition = $this->getYPosition($direction, $startClone, $startBlock);
+
+			$this->secondFace = $this->getZFace($direction);
+			$secondDirection = $this->getZLength($direction);
+			$secondPosition = $this->getZPosition($direction, $startClone, $startBlock);
+
+			$this->thirdFace = $this->getXFace($direction);
+			$thirdDirection = $this->getXLength($direction);
+			$thirdPosition = $this->getXPosition($direction, $startClone, $startBlock);
+		}
+		if($this->getZLength($direction) > $mainDirection){
+			$this->mainFace = $this->getZFace($direction);
+			$mainDirection = $this->getZLength($direction);
+			$mainPosition = $this->getZPosition($direction, $startClone, $startBlock);
+
+			$this->secondFace = $this->getXFace($direction);
+			$secondDirection = $this->getXLength($direction);
+			$secondPosition = $this->getXPosition($direction, $startClone, $startBlock);
+
+			$this->thirdFace = $this->getYFace($direction);
+			$thirdDirection = $this->getYLength($direction);
+			$thirdPosition = $this->getYPosition($direction, $startClone, $startBlock);
+		}
+
+		$d = $mainPosition / $mainDirection;
+		$secondd = $secondPosition - $secondDirection * $d;
+		$thirdd = $thirdPosition - $thirdDirection * $d;
+
+		$this->secondError = floor($secondd * self::$gridSize);
+		$this->secondStep = round($secondDirection / $mainDirection * self::$gridSize);
+		$this->thirdError = floor($thirdd * self::$gridSize);
+		$this->thirdStep = round($thirdDirection / $mainDirection * self::$gridSize);
+
+		if($this->secondError + $this->secondStep <= 0){
+			$this->secondError = -$this->secondStep + 1;
+		}
+
+		if($this->thirdError + $this->thirdStep <= 0){
+			$this->thirdError = -$this->thirdStep + 1;
+		}
+
+		$lastBlock = $startBlock->getSide(Vector3::getOppositeSide($this->mainFace));
+
+		if($this->secondError < 0){
+			$this->secondError += self::$gridSize;
+			$lastBlock = $lastBlock->getSide(Vector3::getOppositeSide($this->secondFace));
+		}
+
+		if($this->thirdError < 0){
+			$this->thirdError += self::$gridSize;
+			$lastBlock = $lastBlock->getSide(Vector3::getOppositeSide($this->thirdFace));
+		}
+
+		$this->secondError -= self::$gridSize;
+		$this->thirdError -= self::$gridSize;
+
+		$this->blockQueue[0] = $lastBlock;
+
+		$this->currentBlock = -1;
+
+		$this->scan();
+
+		$startBlockFound = false;
+
+		for($cnt = $this->currentBlock; $cnt >= 0; --$cnt){
+			if($this->blockEquals($this->blockQueue[$cnt], $startBlock)){
+				$this->currentBlock = $cnt;
+				$startBlockFound = true;
+				break;
+			}
+		}
+
+		if(!$startBlockFound){
+			throw new \Exception("Start block missed in BlockIterator");
+		}
+
+		$this->maxDistanceInt = round($maxDistance / (sqrt($mainDirection ** 2 + $secondDirection ** 2 + $thirdDirection ** 2) / $mainDirection));
+	}
+
+	private function blockEquals(Block $a, Block $b){
+		return $a->x === $b->x and $a->y === $b->y and $a->z === $b->z;
+	}
+
+	private function getXFace(Vector3 $direction){
+		return (($direction->x) > 0) ? Vector3::SIDE_EAST : Vector3::SIDE_WEST;
+	}
+
+	private function getYFace(Vector3 $direction){
+		return (($direction->y) > 0) ? Vector3::SIDE_UP : Vector3::SIDE_DOWN;
+	}
+
+	private function getZFace(Vector3 $direction){
+		return (($direction->z) > 0) ? Vector3::SIDE_SOUTH : Vector3::SIDE_NORTH;
+	}
+
+	private function getXLength(Vector3 $direction){
+		return abs($direction->x);
+	}
+
+	private function getYLength(Vector3 $direction){
+		return abs($direction->y);
+	}
+
+	private function getZLength(Vector3 $direction){
+		return abs($direction->z);
+	}
+
+	private function getPosition($direction, $position, $blockPosition){
+		return $direction > 0 ? ($position - $blockPosition) : ($blockPosition + 1 - $position);
+	}
+
+	private function getXPosition(Vector3 $direction, Vector3 $position, Block $block){
+		return $this->getPosition($direction->x, $position->x, $block->x);
+	}
+
+	private function getYPosition(Vector3 $direction, Vector3 $position, Block $block){
+		return $this->getPosition($direction->y, $position->y, $block->y);
+	}
+
+	private function getZPosition(Vector3 $direction, Vector3 $position, Block $block){
+		return $this->getPosition($direction->z, $position->z, $block->z);
+	}
+
+	public function next(){
+		$this->scan();
+
+		if($this->currentBlock <= -1){
+			throw new \OutOfBoundsException;
+		}else{
+			--$this->currentBlock;
+		}
+	}
+
+	public function current(){
+		return $this->blockQueue[$this->currentBlock];
+	}
+
+	public function rewind(){
+
+	}
+
+	public function key(){
+		return $this->currentBlock;
+	}
+
+	public function valid(){
+		$this->scan();
+		return $this->currentBlock !== -1;
+	}
+
+	private function scan(){
+		if($this->currentBlock >= 0){
+			return;
+		}
+
+		if($this->maxDistance !== 0 and $this->currentDistance > $this->maxDistanceInt){
+			$this->end = true;
+			return;
+		}
+
+		if($this->end){
+			return;
+		}
+
+		++$this->currentDistance;
+
+		$this->secondError += $this->secondStep;
+		$this->thirdError += $this->thirdStep;
+
+		if($this->secondError > 0 and $this->thirdError > 0){
+			$this->blockQueue[2] = $this->blockQueue[0]->getSide($this->mainFace);
+
+			if($this->secondStep * $this->thirdError < $this->thirdStep * $this->secondError){
+				$this->blockQueue[1] = $this->blockQueue[2]->getSide($this->secondFace);
+				$this->blockQueue[0] = $this->blockQueue[1]->getSide($this->thirdFace);
+			}else{
+				$this->blockQueue[1] = $this->blockQueue[2]->getSide($this->thirdFace);
+				$this->blockQueue[0] = $this->blockQueue[1]->getSide($this->secondFace);
+			}
+
+			$this->thirdError -= self::$gridSize;
+			$this->secondError -= self::$gridSize;
+			$this->currentBlock = 2;
+		}elseif($this->secondError > 0){
+			$this->blockQueue[1] = $this->blockQueue[0]->getSide($this->mainFace);
+			$this->blockQueue[0] = $this->blockQueue[1]->getSide($this->thirdFace);
+			$this->secondError -= self::$gridSize;
+			$this->currentBlock = 1;
+		}elseif($this->thirdError > 0){
+			$this->blockQueue[1] = $this->blockQueue[0]->getSide($this->mainFace);
+			$this->blockQueue[0] = $this->blockQueue[1]->getSide($this->secondFace);
+			$this->thirdError -= self::$gridSize;
+			$this->currentBlock = 1;
+		}else{
+			$this->blockQueue[0] = $this->blockQueue[0]->getSide($this->mainFace);
+			$this->currentBlock = 0;
+		}
+	}
+}
\ No newline at end of file