Can I block creation of new Nether Portals in vanilla Minecraft?
In vanilla Minecraft, is it possible to block creation of new Nether portals? This is for a Survival/Adventure hybrid map; I want the player to have a great deal of freedom, but to control access to the Nether to portals I've placed in the world. I can ask players to not build new portals, but it would be nice to have the rule mechanically enforced.
Possibilities include: somehow detecting and destroying the Nether portal blocks when they appear; not allowing the portal to be activated in the first place, and damaging the obsidian frame; somehow "tainting" any obsidian in the world or created so it's no longer eligible to be part of a port.
I'm at a loss for what a solution might look like beyond "Probably some command blocks." Trying to /testforblock every block in the world seems impractical.
Best Answer
You should use the /fill command to replace nether portal blocks with air. You don't want this running all of the time though, only when a player uses flint and steel. First, create an objective to track when flint and steel is used:
/scoreboard objectives add usedFaS stat.useItem.minecraft.flint_and_steel
Then, run these two commands on a clock in this order to clear nether portals around the player who just used a flint and steel:
/execute @a[score_usedFaS_min=1] ~ ~ ~ /fill ~-6 ~-6 ~-6 ~6 ~6 ~6 air 0 replace portal
/scoreboard players set @a[score_usedFaS_min=1] usedFaS 0
Note that this will replace any portals nearby, so you should have something to relight the portals that you want to stay lit.
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Can you disable Nether portals?
The distance that your new portal needs to be away from the old one isn't terribly large, only 128 blocks, but it's measured in terms of the destination world; every block in the Nether is worth eight in the overworld, meaning you'll need to move around 1024 blocks or so away to keep a new portal from joining the one ...How many blocks does it take to stop a new Nether portal?
If such space is found nearby, all will be good, the new portal will lead back to the same one in the overworld. Note that the game will only scan within the map height. That means that if you place a portal above the nether ceiling, it won't be found, and the game will create a new one for you.How to Unlink Nether Portals in Minecraft
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Answer 2
Removing flint and steel or obsidian from the inventory would require a simple /clear command like the following
/clear @a flint_and_steel /clear @a obsidian /clear @a fire_charge
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