How do enemy spawns work?

[Brids17]

I was thinking about trying to make an underground castle however I noticed that enemies seem to spawn underground regardless of the presence of torches. So I was wondering if enemies just always spawn once you go deep enough of if the player can prevent them somehow? Also, if I can stop them from spawning inside my home, will they still build up outside of it at all times?

[JustAGamerPerson]

Originally posted by Brids17:

I was thinking about trying to make an underground castle however I noticed that enemies seem to spawn underground regardless of the presence of torches. So I was wondering if enemies just always spawn once you go deep enough of if the player can prevent them somehow? Also, if I can stop them from spawning inside my home, will they still build up outside of it at all times?

I’m pretty sure enemies usually only spawn around where the player is.

[Moriibund]

There is a very specific cube around the player that mobs can spawn... they will not spawn on lava, or where there are player placed walls.

[baby chungus]

It's not torches that stop enemy spawn, it's player-placed background walls and NPC presence that do

[Tundra1Fox8]

Originally posted by Brids17:

I was thinking about trying to make an underground castle however I noticed that enemies seem to spawn underground regardless of the presence of torches. So I was wondering if enemies just always spawn once you go deep enough of if the player can prevent them somehow? Also, if I can stop them from spawning inside my home, will they still build up outside of it at all times?

replace the underground background walls

[Brids17]

Oooh, that makes much more sense. So I just need to make sure I've got the background filled in then. That seems doable.

[LotusBlade]

Spawn, as i remember, also depends on screen resolution size. So, lets say you zoom in to max — now they spawn outside of your view very close to you. If you zoom out, you automaticly increase screen size borders and mobs spawn much farther away.

Backwalls will not stop spawning if it is bloodmoon, nor houses will. (or was it changed in 1.4?)
Monsters need block of space to spawn (even flying?) so if you fill 99% blocks with lava, they will spawn on remaining 1% block place.

You can place peace candle (-33%?) and sunflower (-15%?) to reduce spawn rates.
The more NPC are around, the bigger is hostile spawn penalty (you can even say, monsters spawn turns into critters spawn).

So, the best thing you can do like this:
I_________________lava_______I"houses"I______lava_______I...normal blocks...

[Angela™]

To be more precise, the exact spawn distance from a player is at least 124x70 blocks away (62 left or right, 35 up or down) and at most 168x94.

This means when you stand still, 64 blocks minimum to 86 blocks maximum is a valid spawn range, which is just offscreen at 100% zoom on 1080 resolution.

Likewise, 35 to 47 up or down, or exactly 3 blocks up from when you are still able to see the floor.

https://terraria.gamepedia.com/NPC_spawning

As mentioned, using peace candles, sunflowers, npc housing and so on are all valid ways to reduce spawns but if you want to be more precise, fill in the areas where monsters can spawn with solid blocks or build lava moats as described.

Don't forget to take into account that different biomes have different spawn rates.

[Crazy Nick]

Are enemies supposed to be able to spawn inside houses? I've been noticing a lot of that lately.

[Junior]

Minecraft uses lights to prevent spawns, terraria its all about player placed stuff.

[LotusBlade]

Originally posted by Crazy Nick:

Are enemies supposed to be able to spawn inside houses? I've been noticing a lot of that lately.

Yes, read my message "6" above.