Interaction checks happen using the plane and not 3d space

src/pocketmine/Player.php

@@ -80,6 +80,7 @@ use pocketmine\level\Location;
 use pocketmine\level\Position;
 use pocketmine\level\sound\LaunchSound;
 use pocketmine\math\AxisAlignedBB;
+use pocketmine\math\Vector2;
 use pocketmine\math\Vector3;
 use pocketmine\metadata\MetadataValue;
 use pocketmine\nbt\NBT;
@@ -1455,10 +1456,14 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 	}
 
 	public function canInteract(Vector3 $pos, $maxDistance, $maxDiff = 0.5){
-		$dV = $this->getDirectionVector();
-		$dot = $dV->dot($this);
-		$dot1 = $dV->dot($pos);
-		return ($dot1 - $dot) >= -$maxDiff and $this->distanceSquared($pos) <= $maxDistance ** 2;
+		if($this->distanceSquared($pos) > $maxDistance ** 2){
+			return false;
+		}
+
+		$dV = $this->getDirectionPlane();
+		$dot = $dV->dot(new Vector2($this->x, $this->z));
+		$dot1 = $dV->dot(new Vector2($pos->x, $pos->z));
+		return ($dot1 - $dot) >= -$maxDiff;
 	}
 
 	/**

src/pocketmine/entity/Entity.php

@@ -40,6 +40,7 @@ use pocketmine\level\Location;
 use pocketmine\level\Position;
 use pocketmine\math\AxisAlignedBB;
 use pocketmine\math\Math;
+use pocketmine\math\Vector2;
 use pocketmine\math\Vector3;
 use pocketmine\metadata\Metadatable;
 use pocketmine\metadata\MetadataValue;
@@ -834,7 +835,11 @@ abstract class Entity extends Location implements Metadatable{
 		$x = -$xz * sin(deg2rad($this->yaw));
 		$z = $xz * cos(deg2rad($this->yaw));
 
-		return new Vector3($x, $y, $z);
+		return (new Vector3($x, $y, $z))->normalize();
+	}
+
+	public function getDirectionPlane(){
+		return (new Vector2(-cos(deg2rad($this->yaw) - M_PI_2), -sin(deg2rad($this->yaw) - M_PI_2)))->normalize();
 	}
 
 	public function onUpdate($currentTick){

src/pocketmine/math/Vector2.php

@@ -115,9 +115,9 @@ class Vector2{
 	}
 
 	public function normalize(){
-		$len = $this->length();
+		$len = $this->lengthSquared();
 		if($len != 0){
-			return $this->divide($len);
+			return $this->divide(sqrt($len));
 		}
 
 		return new Vector2(0, 0);

src/pocketmine/math/Vector3.php

@@ -206,9 +206,9 @@ class Vector3{
 	 * @return Vector3
 	 */
 	public function normalize(){
-		$len = $this->length();
+		$len = $this->lengthSquared();
 		if($len != 0){
-			return $this->divide($len);
+			return $this->divide(sqrt($len));
 		}
 
 		return new Vector3(0, 0, 0);