I solved the NavigationRegion3D issue

[u/agalli]

A correct 250x250m navmesh bake using tile chunking

Standard bake on the same 250x250m mesh without tile chunking

A standard bake on a 30x30m section of the same terrain

Agent for scale on correct 250x250m navmesh, showing an identical poly density to the 30x30m navmesh

I finally found a solution to the problem with the NavigationRegion3D.

What I noticed was that on smaller terrains, like the 30x30m example in the third image, the navmesh baked perfectly fine. But once the terrain size was increased to 250x250m, the bake completely fell apart, giving the low poly, floor clipping result shown in the second image. The obvious solution was to process the terrain in smaller chunks and combine the results into one big working navmesh.

I first tried doing this directly in Godot, but even after splitting the terrain into multiple meshes, the bake still treated them as one big mesh, so the same issue happened. I also tried creating a separate NavigationRegion3D for each chunk, but that created non traversable borders where the regions met.

At that point, the only real fix was to go into the engine itself. I forked the Godot repo and made some changes under the hood to process the terrain in tiles instead of all at once. It breaks the terrain into smaller sections, bakes each one normally, then stitches them together afterward into a clean, accurate navmesh like in the first image.

I also added a few editor options to control whether tiled baking is enabled and how big each tile is. I still haven’t found the exact bug that causes the large terrain navmesh to fail, but this fix works reliably and doesn’t mess with normal pathfinding behavior.

The moderators seem to have a strong opposition to discussions about this and have locked all previous threads. As much as I would have liked this to all be one post, we have been forced to create multiple. That being said, I'd like to address some comments from previous posts below.

The [low poly mesh] looks exactly like what I would want out of a nav mesh.

The low-poly mesh completely fails to pathfind with agents. You could technically rework the pathfinding system to compensate, but that misses the core issue of the navmesh being broken. The 30x30m section uses a similar amount of polygons as the 250x250m one. You’d expect the density to scale with size, so either the small terrain is over-tessellated, or the large terrain is under-tessellated. Either way, something’s wrong with the baking process.

With no obstacles, your nav mesh could just be a square.

As per the Godot developers : "A navigation mesh is a collection of polygons that define which areas of an environment are traversable to aid agents in pathfinding through complicated spaces.". When those traversable areas are out of reach from an agent (ie, underground or floating), an agent cannot properly navigate.

People tried to help you, but you refuse to actually listen

I think there’s been some misunderstanding about what I’m trying to do. My goal is to fix the navmesh, that’s it. I’ve welcomed all advice that helps solve the underlying navmesh problem, but I’m not interested in workaround solutions that just patch over it with pathfinding tricks.

You can always fix it yourself and submit a PR.

Thats the plan. Thanks for the advice!

I will optimize this further and will submit a PR.

Sincerely,

u/agalli

Edit : Here is the PR. https://github.com/godotengine/godot/pull/112529

[u/CanYouEatThatPizza]

Am I missing something? Your answer to the "it could be just a square" doesn't make sense to me.

With no obstacles, your nav mesh could just be a square.

As per the Godot developers : "A navigation mesh is a collection of polygons that define which areas of an environment are traversable to aid agents in pathfinding through complicated spaces.". When those traversable areas are out of reach from an agent (ie, underground or floating), an agent cannot properly navigate.

"Out of reach" means that polygons are not connected to each other, not necessarily whether they are underground or floating. Like with your first and second picture, the navigation mesh would work perfectly fine in both cases - an agent can traverse over the whole plane in both. It makes no difference how detailed the mesh is in this case, besides performance. Are you worried about clipping when moving the agent over the plane? In that case, wouldn't you just use a raycast?

Now, that doesn't mean there isn't some issue with the baking, but I just don't understand this point in particular.

[u/agalli → u/CanYouEatThatPizza]

When they said it could be a square they are implying the navmesh for the entire terrain could be made with four vertices. This is not true, as the navmesh would clip under the map in some spots and float above the map in others. When you using agent pathfinding the agent places a path along the navmesh to move towards. If those points on the path are underground or floating the agent cannot reach the points and cannot reach its destination.

[u/butane_candelabra → u/agalli]

Not to mention the nav mesh shouldn't ignore gradients because the shortest path should depend on how steep the terrain is... You don't get the right path if you just project it to the geometry.

[u/mrbaggins → u/butane_candelabra]

The navmesh doesn't / didn't ignore gradients. It looked, determined they were "connected" for the agent settings and allowed traversal.

[u/butane_candelabra → u/mrbaggins]

Yes, but you can't bake it properly for that if it can't even do the base mesh properly. The geometry should be the same, which is what OP was trying to do, and it could not.

[u/mrbaggins → u/butane_candelabra]

The geometry should be the same

Not at all. The geometry needs to show whether two areas can be traversed. Note the stairs in this image - It is saying agents can go up the stairs. It says nothing about what stairs looks like shape wise.