Add NavigationServer random point queries

[smix8]

Adds query functions to get random points on navigation mesh to the NavigationServer.

Implements godotengine/godot-proposals#6181.

Random points can be queried per navigation map or per navigation region.
Random points can be queried uniformly (costs more performance) or not.

[AThousandShips]

It looks like there's some setup each time queried, would it be worth it to allow batching this, requesting several points at once?

[smix8]

@AThousandShips
I am not sure. It would complicate the API to return multiple points for something that is not really performance critical and since the query allows for a navigation_layers filter caching parts of it is properly not very efficient with all the possible variants. I would guess people would also expect more or less equally spaced random positions when requesting multiple points, something that is not intended to be covered here.

[AThousandShips]

Agreed, saw after commenting that the area of the regions are cached which would be the only real performance bottleneck, when pondering possible implementation of this on the original proposal I was considering an idea where a query structure could be returned which contained the areas for weighted lookup (i.e. how you solve it here), but I don't think the complexity is worth it, I don't think you'd do queries like this that often

[AThousandShips]

Will test the code when I have the time but the code looks good to me

[AThousandShips]

The code looks good, unable to do any real runtime testing myself

[akien-mga]

Thanks!

[tudor07]

I needed this, thank you so much!

[esklarski]

Wow wow wow ❤️

Thanks to everyone involved! This was just the thing I was looking for.

[Dorifor]

region_get_random_point() does return me a Vector3 but it's always of value (0, 0, 0), has this happened to anyone ?

map_get_random_point() does work but only like half of the time, otherwise I also get the same value as region.

edit: thanks @jadenrose for the assistance 🙏

[jadenrose]

region_get_random_point() does return me a Vector3 but it's always of value (0, 0, 0), has this happened to anyone ?

map_get_random_point() does work but only like half of the time, otherwise I also get the same value as region.

I just ran into this issue as well! According to the docs, any procedural operations won't be ready to use until 1 physics frame after the NavigationServer is mounted, at least that's my understanding. To solve this, I deferred my call to the method that was querying the server, then at the top of that method, I waited for a get_tree().physics_frame signal. After that, the queries started to work consistently.

Example:

  func on_enter():
-   goto_random_destination()
+   goto_random_destination.call_deferred()

...

  func goto_random_destination():
+   await get_tree().physics_frame

    # ... get your map/region
    var random_point = NavigationServer3D.map_get_random_point(map, 1, false) # no longer returning (0, 0, 0)

I think what this does is ensures that 1) The method gets called on the 2nd process frame (or the end of the 1st, I'm rusty on the specifics) so all your nodes are already in the tree and 2) The method waits for the server to do its setup (which happens during the first physics frame after the initial render) before trying to query it. Presumably, you could also just wait for an arbitrary number of milliseconds before querying the first time, but I like this way because there's no possibility of a race condition.