Planning Defenses: How Does Mob Spawning & Pathfinding Work?

[Eunomiac]

I'm trying to get a better feel for how mob attacks on the CPH actually function, because up till now I've just been adding more guns---but I'm getting the sense that won't work for much longer. I've searched through these forums, but I'm not sure what information is still current, so I thought I'd set up a place to summarize what we know.

(Note: by "mob", in this context, I mean specifically those that spawn above-ground and assault your CPH directly---not Mynochs or Camobots or things like that.)

• Where do mobs spawn from? I've heard the developer say that you have roughly 300m to defend your CPH, so I assume "at least 300m away" is part of the answer. Waves seem to come at me from any direction, so does that mean mobs can spawn from anywhere outside that 300m radius, or does it mean there are multiple "spawn points" surrounding my base? Is it possible to block off attacks from certain directions, to consolidate defenses elsewhere?
  
• How high can wasps fly to get over obstacles in their way? Is it possible to build a maze of walls or tunnels leading to your CPH, or otherwise control/influence the path the mobs take?
  
• Under what conditions (if any) can a mob clip or "ghost" through an obstacle in its way? I'm not sure if this was an old mechanic that has since been removed, or if this still happens if you build your defenses too well.
  
• Can mob projectiles pass through walls? I notice wasps clipping into the ground, sometimes even shooting out of a mountain they've ghosted three or four blocks into (though I haven't seen that recently, either because my defenses are better or because this was a bug that has been fixed). After seeing that, I just sort of assumed they could ghost their projectiles through any walls I built too, and didn't bother building any :)
  
• Do mobs attack anything other than your CPH? Many of the building blocks describe themselves in terms of their strength/durability, which makes me wonder if wasps will start pummelling your walls if they can't get to your CPH.
  
• How do you use Threat Scanners to "triangulate" mob direction, and what does powering a Threat Scanner accomplish? Using scanners to triangulate is mentioned in the help file, but I've no idea how this works. And I can't see any obvious differences between a powered Threat Scanner and an unpowered one.

Lastly, in broad strokes: What strategies work best for you in defending your base into the middle and late game? What general tips/tricks have you learned that others might find useful?

[Demerzel]

In my world mobs attack from 4 direction totaly random. If you go in one direction you will find where is the spawn point. So the optimal defense would be to start putting down towers to there and put other towers along the way to your base.
If you wall your CPH they will start to attack from the sky. I seen more than 40m high towers.
They don't attack anything other the cph but if they destroy your cph the oet charge level goes to zero.

[Demerzel]

The threat is how big the attack will be. The higher the threat the bigger the attack. 20000 is the top threat level.
Threat is growing as you use more machines.

[DjArcas]

1) Mobs spawn +-320 along the XZ plane
2) Infinite height. Don't try and wall yourself in, or I'll implement mobs that can bore holes in walls.
3) If you build a wall since the mob has spawned, it doesn't recheck. No other circumstances. You'll see them go through walls, but this is actually just interpolation errors between simulation and graphics.
4) No. The CPH precalculates visibility spots, and the wasps attack from there.
5) No.
6) Not yet. Follow the Spiderbot!

[Undead_Duckling]

There are four directions mobs will attack from. There's no hive or anything, they pretty much just pop out of the ground if you follow them to their spawning point.

Mobs don't care about walls. In fact there will be mobs that tunnel through mountains or any other obstacle to create attack paths for their wasp brethren.
But let's say you build a 50 block high wall around your CPH, mobs will just fly higher up, probably be out of range for your turrets and attack from above.

I'm not sure they can shoot through walls, but you don't want them anywhere near you CPH anyway.

Wasps are the only mobs that will go for your CPH, but there are other critters in the game you need to worry about.

Threat scanners just show you how high your threat level is and how many mobs will attack.
I don't think you can use it to detect where the next wave is coming from and 'yes' it doesn't seem to make any difference if it has power or not.

My tip for defending: Take the fight to the enemy. Have several turret nests going from near your CPH all the way to where the mobs spawn, so they'll be under constant fire.
If your goal is to build and charge the OET, then I recommend build lots of missiles so you won't run out of ammo when things get ugly.

[HDL_CinC_Dragon]

Originally posted by DjArcas:

2) Infinite height. Don't try and wall yourself in, or I'll implement mobs that can bore holes in walls.

Tunnel Nuker straight to your kitchen table!

I've noticed that the mobs attack from four different directions (one at a time/attack) so what I've done is leveled any mountains that were blocking their path from coming directly on-plane to my defensive weapons. I've thought about setting up 'gun bunkers' further out but figured I would just handle them when they got close-by that way the added threat of the extra weapons will always be used to handle the extra threat response of the wasps that it caused in the first place lol(Granted, I'm only getting ~300 wasps per attack so far and no bosses yet so we'll see how that holds up later[cue hard lesson]). I basically just surrounded my CPH with MK2 and MK3 turrets in a way that made sense given their range differences and such.