How far do I have to place torches so that mobs will not spawn near me?

  • Since torches prevent mobs from spawning, is it possible to place enough torches within a specific radius to ensure safety during the night? I'm thinking of a situation without any shelter built, more along the lines of a flat plain. If it is possible, how many torches/how far out do I need to go to make that area safe?

    Best to make sure by using F3 to show the light level of the block you are standing on. If it's 7 or lower, you need your torches/lanterns/glowstone to be closer together.

  • badp

    badp Correct answer

    10 years ago
    1. Learn about light:

      • Sunlight gives 15 luminance to the blocks it hits directly, or through half steps.
      • Lava gives 15 luminance.
      • Glowstone gives 15 luminance.
      • A Jack-o-lantern gives 15 luminance.
      • A Torch gives 14 luminance to the otherwise empty block it occupies.
      • A Redstone torch gives 7 luminance to the otherwise empty block it occupies.
      • Every tile that isn't a light source has a luminance of one minus the luminance of its neighbors. For example, if you had a 6 and a 4 luminance sources close to each other, attached to a wall, you'd have this distribution:

                    1
                   121
              1   12321
             121 1234321
            1232123454321
           123432345654321
            12┴─────┴4321
             1     12321
                    121
                     1  
        

        ...except this works in three dimensions instead of two!

    2. Learn about spawning:

      1. The following applies to any difficulty, except for Easy.
      2. Every tile within 24 distance of the player is not eligible.
      3. Every tile outside a 144×144 square centered on you is not eligible.
        • Every non-glass, non-half step surface in the outer world with 7 or less luminance is eligible for spawning.
        • Every non-glass, non-half step surface in the Nether is eligible for spawning.
      4. Mob spawners cause mob to spawn at a high rate in any surface within 5 distance of it.

    3. In practice:

      Here's what I try to do to ensure a luminance of 7 consistently along a line:

      1. Place the first torch. Pardon my hexadecimal one-sided luminance graph:

        EDCBA98765432100000000000000000
        ↑
        
      2. Proceed until you find two tiles looking exactly like the next, then go back one.

        EDCBA98765432100000000000000000
                     ↑
        
      3. Plant a torch there. Lo and behold, minimum luminance there will be 8!

        EDCBA9889ABCDEDCBA98765432100
                     ↑
        
      4. GOTO 1

      You can adapt this algorithm to your necessities with ease. Just plant a torch in the darkest area when in doubt. (Duh.)

      Also:

      • Put torches directly onto surfaces for best results.
      • In your mining, be aware that any surface is good enough to spawn...

        ↓↓↓ ↓↓    All positions marked with an arrow are valid
        ███ ██↓   spawning points, to the best of my knowledge,
        █     █↓  and they all can lead to the just spawned mob
        █      █  to reach you.
        █     ↓█
        █↓↓↓↓↓█   Be vigilant and don't mine caves from the
        ███████   bottom up :(
        
    4. Learn how to keep mob that has spawned outside: make traps.

      • Mobs can only jump up one tile. Make pits deeper than that and, once in, they will be trapped (skeletons are still dangerous and spiders can climb out).
      • Mobs cannot deconstruct. Make walls. (Be aware creepers do explode, if they get close enough.) Use cobblestone: they have high explosion resistance and can't catch fire.
      • Mobs cannot use items. Protect your entrance with a wooden door. Plant it from the outside, or skeletons will be able to hurt you with their arrows!
      • Mobs' path finding is somewhat dumb. Protect your spawn point with water and liberal amounts of cactus (arrange them in a chequered pattern.)

    The algorithm gives you the least amount of torches you can possibly use to get 8 minimum luminance in a row. That's the bare minimum, and it is useful to know: anything more than that will keep you safe.

    I'm interested in what you said about glass and half-steps -- if I build a fortress out of these two materials, I'll be spawn-free even if I miss a torch or two? Also, does that only count half-steps that make a half-block-high surface, or can I stack two half-steps for a clean white floor (or as the step between a half step and a block+half-step step) and remain mob-free?

    One question, just to confirm - so light from two sources is *not* additive? I would have thought that the light next to the "4" square would also be "4", from 3 + 1 from the "6".

    @Cyclops Light is not addictive indeed -- and it isn't in "real life" either :) Lighting a torch under direct sunlight doesn't actually accomplish anything.

    @badp, ah, yes, actually, light *is* additive in the real world :) Also, trains *can* reach velocities higher than 8 m/s, and leave piles, sadly, do not instantly decay. :)

    @cyclops Light is additive in frequency certainly. If you wish to discuss this any further may I suggest physics.stackexchange.com? I unfortunately lack formal education in optics, or human perception thereof ;)

    Just one thing: why goto? https://xkcd.com/292/

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Content dated before 6/26/2020 9:53 AM