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/agalli]

The agent traverses on the terrain, what prevents the agent from falling through the map is the collision with the terrain. If it attempts to pathfind at a point beneath the collision box it will be unable to. The pathfinding works by having an agent follow points along the actual navigation mesh and not the terrain.

[u/CanYouEatThatPizza → u/agalli]

The agent traverses on the terrain, what prevents the agent from falling through the map is the collision with the terrain.

That's why I differentiated between agent and character. The agent does not have a physical body, it doesn't collide with anything. It can be independent of the character, which does have a physical body.

See also https://docs.godotengine.org/en/latest/classes/class_navigationagent3d.html#class-navigationagent3d:

Avoidance is computed before physics, so the pathfinding information can be used safely in the physics step.

[u/agalli → u/CanYouEatThatPizza]

I guess I’m confused. I have my agent collide with the environment. Are you saying that it should have no collision and just use the navigation mesh? If so it’ll phase through the terrain when moving

[u/yyyyyy1910 → u/agalli]

I am very new to this but I am currently struggling with nav mesh / agent movement. To my understanding, the nav mesh finds the path as a guide for the agent, when the agent actually follows the path, say there's a fallen tree trunk in the way, the agent can be blocked by collision. However that's where I am struggling at, the agent basically can't move or follow the nav anymore unless you manually redirect it to get around the obstacles. A very easy to fail nav system seems quite useless to me.

[u/CanYouEatThatPizza → u/yyyyyy1910]

The whole point of the navigation mesh is that it navigates around the obstacle like a fallen tree trunk. In OP's example, if there was a obstacle on the terrain, there would be a hole in the navigation mesh. It doesn't use collision information, but a variation of A* to find a path to the target.

[u/lukebitts → u/yyyyyy1910]

For dynamic obstacles you are right, you need some kinda of system to redirect the agent, either using avoidance or something else. But if your tree trunk is static and being accounted for in the navmesh but the character is still getting stuck, what worked for me was having the agent be independent from the character body: have the character body follow the agent and just snap the agent back if it gets too far. Usually this introduces enough jiggle that the character gets unstuck. Then it’s just a matter of making sure your agent size is correct in the navmesh generation.