Navigation Mesh missing entire chunks of the map

Lightning_Splash · July 20, 2024, 9:48pm

hey, about three months ago we started getting issues with one of our game’s monsters completely failing to navigate throughout its room. we couldn’t figure out the issue at the time but have now realized the Navigation Mesh randomly misses entire chunks of the map.

we didn’t update the live game for about a month when this bug started appearing, so I don’t think that it’s our fault.

we’ve tried:

adding PathfindingModifiers almost everywhere in multiple ways to avoid or prioritize areas
removing and adjusting chunks of the map, even up to the point where it was just 5 parts
completely remaking & rewriting the pathfinding NPC
changing the rooms’ position and orientation
changing the agent’s parameters
changing the pathfinding parameters
removing all PathfindingModifiers from the game entirely

the navigation mesh looks like this in studio, and the navigation mesh even looks like this in-game until pathfinding starts:

remember that our NPC worked as intended before this mysterious change to the pathfinding system.

this bug is completely inconsistent. it will disappear and reappear chunks at random.

the bug’s common enough to where it ruins the experience for a good chunk of players upon encountering our pathfinding NPC Figure in the game just for it to walk into a wall and do nothing for the rest of the playthrough.

even after completely recreating & rewriting this NPC, the pathfinding/navigation mesh is still completely breaking for us, both in studio and in-game (in a different testing experience).

we just can’t figure out this bug. it has completely wasted about a week of development. we think it’s linked to maybe some sort of engine change done around 3 months ago that changed how pathfinding and the Navigation Mesh function; we’ve asked another developer and they’ve had a very similar issue with the Navigation Mesh randomly missing entire chunks of a map. we cannot ship our game’s update out without this bug being fixed as it genuinely ruins the experience.

NicolaiXeno · July 20, 2024, 10:21pm

We are experiencing similar issues with the navmesh in nico’s nextbots to the point where it has made one of our maps completely unplayable. None of our bots are working since entire chunks of the navmesh would just disappear whenever a state change happened.

This has never happened to us before. We’ve tried every possible fix, but nothing works. The navmesh just fails to recalculate, even after we revert all of our changes.

I’m not exactly sure what causes this, but I believe it has something to do with the way pathfinding modifiers are handled internally, as we’ve only observed this on maps that do make use of them.

I’m hoping this gets resolved quickly as this is severely impacting our game.

GamesVitaliy · July 21, 2024, 12:00am

I played Doors today on my phone, but figure followed me normally (I didn’t saw any differences). I don’t even know what’s the issue.

bloodbonniekingnoob1 · July 21, 2024, 12:12am

Roblox pathfinding is such a joke and ue3 had better pathfinding. It’s also so damn difficult to make it work correctly on moving targets and Roblox never gives solid examples in the documentation

Lightning_Splash · July 21, 2024, 12:18am

that’s part of the issue though, this bug is very random and inconsistent

TheOriginalGoatMan2 · July 21, 2024, 12:31am

How do you check the navigation mesh during a running game? It disappears whenever I start a Studio test. I’m wondering if the problem you’ve described could maybe be the culprit behind a pathfinding issue I’ve been having in one of my Piggy fangames.

Beloathed · July 21, 2024, 12:42am

ROBLOX should allow you to create your own navigation mesh, kind of like how GMod does.

QALOLTHING · July 21, 2024, 1:32am

Some thing I found out was that the navmesh only disappears during runtime.
Maybe try using custom a* pathfinding, because honestly using rblx pathfinding isn’t worth it.

NicolaiXeno · July 21, 2024, 1:58am

It doesn’t only happen during runtime that’s false. I demonstrated that in the video.

QALOLTHING · July 21, 2024, 1:59am

for me it is. When i start my game half the navmesh just dissapears.

pankii_kust · July 21, 2024, 5:08pm

Same issue happens to my game, one if i remember that it happened months ago and I’ve seen it in one of my beloved game often, tried to bounce the NPCs back but it still wouldn’t restart it’s path to find

hyde12345678 · July 21, 2024, 5:08pm

I can also say I’ve expierenced this issue when reaching The Library.

Figure has been crashing into walls more often & is generally way more unpredictable.

Hope a fix can be made soon.

crazycat2789 · July 21, 2024, 9:04pm

thats really weird does the code have anything to do with this tho?

NicolaiXeno · July 21, 2024, 9:56pm

The point of failure lies in the navmesh itself, not in the use of the pathfinding service. This is not caused by code on our end.

I’m just moving the part around in studio and it’s just deleting chunks of the navmesh.

QALOLTHING · July 22, 2024, 3:07am

its really annoying when im testing smth and the npcs just get stuck. It kinda looks like its stuck on an invisible wall ngl

watIsInTheName · July 22, 2024, 4:57pm

Hi, Thanks for reporting this . Could you please share a simplied repo case for us to investigate.

cherrypathy · July 22, 2024, 6:18pm

its really an engine bug/update, i had a game i never updated for like 6 months with this kind of thing and it became unplayable even though no one other than me has access to edit the game and i didnt edit anything for months…

i just found it out because of this post, this is 100% an engine update or bug.

we really need to wait for roblox for this one.

cherrypathy · July 22, 2024, 6:46pm

Huge chunks of gets removed when a part is moving around it? This is what i think is the problem.

I am assuming one of the updates in May (probably version 622) was the cause as it was 3 months prior to this post’s creation date.

NicolaiXeno · July 22, 2024, 10:21pm

Here is a file that reproduces this:
example.rbxm (36.0 KB)

Everything parented under the model is affecting the navmesh. Hope this helps.

oldmannt · July 24, 2024, 10:18pm

Hi NicolaiXeno,
I’ve been investigating the navmesh issue you reported and managed to reproduce it in the repo you provided. I found that the problem arises because several base parts are positioned at an extremely low Y coordinate (Y=-999390).

Workspace.nn_outpost.nn_outpost.outer_props.foliage.Bush2                    Pos: 311.48492431640625, -999390.125, -190.41192626953125
Workspace.nn_outpost.nn_outpost.outer_props.foliage.Snowy Tree 6.Trunk       Pos: 311.48492431640625, -999390.125, -190.41192626953125
Workspace.nn_outpost.nn_outpost.outer_props.foliage.Snowy Tree 6.Snow Leaves Pos: 311.48492431640625, -999390.125, -190.41192626953125

We’ve previously encountered and fixed issues when base parts are placed at extreme depths, but this instance seems a bit different, and we’re still working on a solution.

As a temporary fix, you can resolve this issue by deleting the base parts at Y=-999390. Also, please check other problematic places to see if they have base parts positioned at unusually high or low locations. Removing these could potentially fix the issues as well.

Thank you.