add navgen option walkableRadiusFactor

[sweet235]

There is a margin between the edge of a navmesh, and the actual geometry causing this edge. Look at the level4 navmesh on map antares for example:

Notice how these margins cause a gap in the navmesh, where the white circle is. The tyrant bots will not leave their base on this path, despite the fact that a tyrant fits in there.

This is very unfortunate, as there is a similar gap at the other exit as well. So tyrant bots cannot leave their base.

The margin is controlled by a value walkableRadius we tell recast to use. Add a navgen option walkableRadiusFactor, to tweak this value. For example, create a file game/maps/antares.navcfg:

walkableRadiusFactor 0.75

Restart, and look at the same navmesh:

There is one other important reason to keep the margins as small as we can: bots will only pick enemy buildings as targets if their origin is over the navmesh (with minor exceptions).

This is a very dangerous value to tweak. Make the margin too small, and bots might get stuck at little edges on the walls.

[DolceTriade]

Should this be a per-class value?

[sweet235]

Should this be a per-class value?

Probably. Some navgen options should be. But we did not implement per-class configs yet.

[sweet235]

This is a very dangerous value to tweak.

Indeed. Setting it to 0.1, and generating navmeshes for map kaiji-starsidehotel crashes the server.

I'll try find out what a proper lower bound is.

[DolceTriade]

Why did it crash? Can 0.1 be a valid value for some maps but cause others to crash?

[sweet235]

Why did it crash?

I suspect these narrow bridges:

I could not make any bot cross them yet.

Can 0.1 be a valid value for some maps but cause others to crash?

I'm not sure yet.

[sweet235]

Note to self: it has been communicated to me in private that a minimum of 2 could be enough for both values.