The jumpdrive can jump into the void

[Monniasza]

Hi. I've seen the Void House on Pandorabox at /spawn > lga's Tiny Town > Museum of oddities > O-162 > mission.

It shouldn't be possible to jump there because normally there aren't any blocks. But the blocks below the jumpdrive will jump into the void if the jumpdrive jumps to y=-30912. It will also work with r-30912 for block between (y+30911) and r meters below the jumpdrive, both inclusive.
Jumping there creates a copy of the parts that will end up in the void, which are not removed when the ship jumps back. Also, the copied blocks aren't protected by areas (protectors aren't tested) and mining them drops nothing.
Moreover, placing any blocks in the copy will stop the jumpdrive from jumping into the same part of the void until it is fixed (on Pandorabox by MCLV).

Related to minetest/minetest#15501

[BuckarooBanzay]

this might be fixed with a simple boundary-check adjustment, i don't think this is really an engine issue

EDIT: i somehow can't find the existing boundary check, is there even one? 🤔 (haven't looked at this code in a while, sorry)

[SwissalpS]

As I understand, there is no harm done with this. Player can jump back into universe and all is fine. Correct me if I'm wrong.

[SwissalpS]

Regarding detecting world limits, I currently don't know of any other way than scanning for void nodes. Then again a game may want to prevent players from jumping outside a certain area, so the whole thing could be fixed with such a callback.

Lazifying this as it is really a non-issue to me.

[SwissalpS]

I feel like this should trigger but aparently it doesn't:

jumpdrive/jump.lua

Lines 66 to 67 in 9b36a7a

	if minetest.find_node_near(targetPos, radius, "ignore", true) then
	return false, "Warning: Jump-target is in uncharted area"