PC Zombie pathing calculations and performance

[Deceptive Pastry]

So generally A17 runs better than A16.4 for me, oddly considering my PC isn't that great. 30-40 FPS. Except for when there are 10+ zombies running around, then my FPS PLUMMETS. And it seems to be a result of the pathfiding - Generally don't get much an FPS drop when I just have one big conga line coming straight at me outside. I didn't realize how intricate the pathfinding must be until I spent a horde night in the missile bunker and I have wonder if this is feasible performance wise or any less exploitable than how it was before. Here's the scenario...

Plan was to spend the early part of the night on the roof of the small bunker in the corner. When they got close to breaking in we would run all the way through, through the parking garage, and across a wood frame bridge over the chasm in the elevator shaft. The stairway leading to the main area of the surface was left open at the top and an iron door was placed at the bottom entrance to the parking garage.

Now I know they go to the path of least resistance. While standing on top of the small bunker roof, within 30 seconds of the bloodmoon starting they completely ignored us, went straight down the stairway and began attacking the iron door at the bottom. I had figured they might do this, but this must mean they had calculated the entire way through the bunker and all the way back up to the roof we were standing on...and I have to wonder, how?

Knowing they were going to start attacking the iron door, we ran down to position 2 across the elevator shaft. Crossed the wood frames with them right behind us. The very moment I pulled the wood frames...they all did a 180, ran up the stairs, and as we later discovered, went around down the ramp outside and started attacking the ground directly above us. I figured I could exploit their AI and indeed, as soon as I connected wood frames back to the ledge, they stopped attacking the ground and all came right back down 10-15 seconds later to get across. So the whole night we had them bouncing back and forth as I placed/removed the wood frames. This poses a few questions:

- Again, how? Are there waypoints placed through each POI that they connect to, are they running calculations for every block in a radius and drawing a new path every time? When 15-20 zombies are doing this, I can't imagine this being feasible performance wise? Unless it is just one calculation that all the zombies follow, which would make way more sense. But it seems like different zombies in a group choose different paths sometimes.

- Are these calculations constant, do they set waypoints to easily run back and forth to as routes change? They seemed to realize immediately when a path is no longer feasible. I could image having their pathing updating every few seconds working better? But currently it almost seems constant.

On one hand, I'm impressed, but on the other, I can't imagine how this system wouldn't kill performance. But I also don't know how it works on the back end.

 

[Zourin]

Zombies tend to prefer the easiest route, not necessarily the most direct. They will factor in the HP of doors, which are often a structural weak point if not doubled up, but will likely ignore the presence of garage doors as an obstacle (making them both expensive and worthless).

- If you are within about 2-3 blocks, they'll usually skip the runaround and try to smash to you. Might want to stand back from the walls a little.

- If there's a path to your location that's flat, without jumps or falls, they'll take it over anything else, even an ankle-high wood wedge tip.

- If there's no direct path to your location, they'll try jumping up on blocks or piling on top of one another to create a new route. they'll also try smashing straight down if they're above you.

- If there's no 'step up' path, they target the weakest hp point in their way to your position (wall breach).

- If there's absolutely no way to reach you, TANTRUM and smash things nearby. This is usually what happens when you're standing over them.

I can easily get them to ignore doors if I put two doors back-to-back. That puts enough HP in their way that they'll generally go where I want them to, not where I want me to. I haven't tried this with garage doors, mostly because they're ****ing expensive and they never hesitated to start banging on the things rather than exhibit any consistent behavior, so i assume 'garage doors' are ignored as an obstacle. Do NOT use them without powered defenses like electric fencing or dart traps.

I've run tests and the buggers will take huge detours around simple obstacles like a simple wood-plate wall, which is a good thing, since it lets me have SOME control in the fight by narrowing down a combat zone to focus on. The fact they prefer a flat, direct path means that if I leave a deliberate opening in my perimeter as bait, they will take it 10/10 times. And if that 'flat' path happens to be 'flat' because I filled a pit with spike traps, well, obvious and predictable results occur. As the spikes collapse and break, suddenly, they aren't a preferential route and they walk over the unbroken spikes next to it, and so on, and so on. Once all the spikes are gone, I pretty much move to stage-2 and let them breach that perimeter.

Because I use a barn as a base, stage-2 is basically a bar fight. By bar fight, I mean shooting down through wood/iron bars and hope I clear them before dawn. I have sorely underestimated their tantrum phase and have lost some pretty valuable things like a chem station and a drop box filled with material for my workbench, so it's a good idea to leave the final-phase combat area VERY clear of critical equipment.