Partitioned Navmesh - Unable to make it work on a level.

Development World Creation
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Hello

In our project we use a partitioned level to have a bigger environnement and don’t need to load everything at the same time.

With partitioned level, a partitioned navmesh is requered if you want a navigation area, it’s not possible to use a static navmesh as is a non portitioned world.

I have followed this article to add a partitioned navmesh

https://dev.epicgames.com/documentation/en-us/unreal-engine/world-partitioned-navigation-mesh

The problem :

The partitionned navmesh don’t want to work on our level, the debug never display it and npc can’t move.

  • If i clone the level (save as a new level), the partitionned navmesh work on this new level.
  • The generated assets seem to be ok, they have the same size on the base and the cloned level with the same partition params.
  • Change the resolution of the partitions does not solve the problem, there are more or less generated assets (as intended); but nothing happens.
  • Nothing happen if we sync the navmesh with a grid (but works on the cloned level)
  • It work well if i create a new partitioned level with the default terrain and add a partitioned navmesh on it
  • A standard navmesh with dynamic settings work but is too heavy in performance as it need to be rebuild when the player move

Is there a way to see what is wrong on the level ?

Using the clonned level at the place of the current one is not a solution, it can hide this problem temporarily, but it’s not a fix and does not guarantee that it will not recur again.

Thank you for your answer.

Nicolas LAURENT

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2

Do you have any warnings or errors when building the WP navmesh for the original level? There is a WPNavigationBuilderLog that is generated when building paths for the WP navmesh. It should contain all of the output from the console window that runs the commandlet. I don’t know what would cause the failure of a particular level but not others. Have you attempted removing the NavMeshBoundsVolume and any Recast actors in the level and saving the level. Open it back up and replace the navmesh bounds volume and update the Recast navmesh actor to be world partitioned followed by building paths with the commandlet for the problem level?

I would also highly recommend against having the player Pawn and NPC pawns invalidate navmesh. Using avoidance, NPCs should move around the player and each other when pathing without needing to modify the underlying navmesh. Invalidating the navmesh under moving pawns can cause them to start a brand new pathfind due to one of the tiles the original pathfind crossed over has been invalidated.

-James

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