Hi,
First of all, Im a noob so I wont be able to provide any help in solving this. I do have something I would like to mention about the entire query (that although wont help, is quite important I think
).
Now I did a little research, because, (after watching the tutorial) like you, I thought this may be a pretty cool simple action to try and create (im rubbish at c#, but why not try lol).
What I found was a lot of people saying that you cannot build navmeshes during runtime. I was thinking '
what do they know, I just watched a tutorial on it!'. Then I went back to the tutorial and checked the comments and one guy did confirm this in the comments
. Then I went back to unity forums and yup apparently what is shown in the tutorial will only work at runtime in the editor and not in any standalone published version of the game.
So that kind of makes it seem pretty useless to me now... (except for the script from the tutorial, that can be useful still if youre expecting to work heaily on the level layout as it will adjust the navmesh each time you test it after making changes to the level, but if that is the only real use for it, then I think a playmaker action is useless as the script does the job just fine.)
If you must do it for some reason, I read this:
use 3rd party like Aphex and Aaron's astar
Also there are navmesh obstacles that will work in most cases where this would have been useful.
For all I know this may not be the case anymore (I hate trying to keep up to date with all the damn updates lol), but here are some recent topics confirming this:
http://answers.unity3d.com/questions/1149938/navmesh-at-runtime.html (March 2016)
http://forum.unity3d.com/threads/while-we-wait-for-navmesh-at-runtime-how-do-you-handle-dynamic-levels.391376/ (April 2016)
Good luck with it!