Pocketmine-mp: Method getHighestBlockAt(x, z) always returns the generator block

[matcracker]

Issue description

Using the getHighestBlockAt(x, z) always return the heighest block of level generator.

Steps to reproduce the issue

1. Generate a level (Default or Flat).
2. Fly over some generated blocks (such as trees or caves)
3. Place a block and fly or jump over.
4. Height will result constant in base of chunk generator

OS and versions

• PocketMine-MP: 0f174f7
  
• PHP: 7.0.16
• Server OS: Windows 10
• Game version: PE/Win10 1.0.9/1.0.8

If could be helpful, use this code:

public function onPlayerMove(PlayerMoveEvent $event)
{
    $p = $event->getPlayer();
    $to = $event->getTo();

    $ground = $p->getLevel()->getHighestBlockAt($to->x, $to->z);
    $p->sendMessage("Ground = " . $ground);
}

[Sandertv]

I can confirm getHighestBlockAt often does not return what you expect it to return...

[dktapps]

This is because the heightmap is never updated. This issue is fixed on the mcpe-1.1 branch.

[SOF3]

@matcracker Extracted from CONTRIBUTING.md:

[gizanopatrica]

@dktapps In which commit on the mcpe-1.1 branch was this issue fixed?

[dktapps]

https://github.com/pmmp/PocketMine-MP/commit/dab73d895099e4c1c7d632711e204971cbbb0590