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Play In Editor taking long time to start?

Hi there, I have a project with a terrain of 18km x 18km (rather large) and performance is fine once in game, however I'm starting to put together some AI and upon adding my navigation mesh (approximately 160,000 instructions) my PIE is taking 5+ minutes to start. I've looked around and found that other's have solved this problem be disabling auto-calculate navigation and auto-compiling of blueprints so I've gone ahead and done that to no avail. Could this be due to the system being bogged down upon run time or is this a problem related to the size of my terrain (and therefore my navigation bounds being extremely massive)?

Product Version: UE 4.17
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asked Aug 23 '17 at 11:35 PM in Using UE4

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avatar image CaliberBeats Aug 23 '17 at 11:42 PM

I'd also like to clarify, before adding the navigation mesh, PIE would only take 2-3 seconds even with the large terrain so I'm 95% certain this is nav mesh related?

avatar image merkaba48 Feb 08 '18 at 03:45 PM

Look into dynamic navmesh generation, specifically 'Navigation invoker'.

Basically with such a large terrain, you might be better served dynamically generating the navmesh at runtime where it's needed.

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18km x 18km is a very huge area for the NavMesh to render

You might want to slice up your level into chunks and then use level streaming to load each one of them, so that it's easier on your engine.


Also, you can take a look at this website as a reference on how Unreal deals with it's NavMesh generation (Unreal uses A* for their path finding algorithm)


Use the Euclidean heuristic in the A* section and then try to put the green and red cube at the edge. See how long it takes to generate

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answered Aug 24 '17 at 08:03 AM

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