4.8 navmesh bug - cell size can't be changed

To make sure this isn’t just a problem with my own project, I managed to replicate it in UE4’s top down template.

After making a new top down project, and enabling show navigation on the main viewport, I click on play and the character moves around with no problems.

If I change the “RecastNavMesh-Default” cell size (in the generation category) from 19.0 (the default value) to anything else, and wait for the navigation to build, the character will no longer move around the level and “NAVIGATION NEEDS TO BE REBUILT” appears on the screen. If I set the cell size back to 19, the character still won’t move.

If I click on save all, to save any changes done to the cell size, and then open the project again, the cell size will be at 19.0, regardless of what value I saved it at.

Video: - YouTube

It’s a missing feature actually and it’s on the todo list. Currently we tend to recreate recast navmesh instances on game start, if for some reason the navmesh that’s already on the map doesn’t fit navigation system’s defined supported agents. You can globally change RecastNavMesh's properties in Project Settings.

Cheers,

–mieszko

oh ok thanks a lot, hope it gets fixed soon
cheers!