Ty!

I found the main critical problem.
Functions in http://www.love2d.org/wiki/World:setCallbacks works only in one thread and they cant pass to another.
Same for http://www.love2d.org/wiki/Fixture:setUserData and http://www.love2d.org/wiki/Body:setUserData if userData is table or function (pointer).

I found interesting code, wich help me build navmesh, thanks to Alexar:
https://github.com/AlexarJING/box2dhelp ... 187e299726

Alexar wrote:new update: destructible terrain.

WOW OoO
I will try use this in my 2d navmesh: viewtopic.php?f=5&t=81229#p203666

Alexar, keep doing, don't stop, cool

EntranceJew, keep going please, don't stop, awesome !!!

Yes it is possible, but hard.
I make top down shooter like Hotline:

[update] Exported file format

Found multithreading C++ Box2d library: https://github.com/skitzoid/Box2D-MT

The problem is that checking "isLocked" is not enough, as right after you "ask" whether it is locked, the other thread may also check and then both are still attempting to do stuff at the same time. You will need to use Channel:supply/demand to actually lock threads while workin...