expose dtQueryFilter

[lukasvdelft]

Hi,
I would like to be able to create custom logic for the QueryFilter, especially passFilter/getCost, is it possible that this class gets fully exposed? Rough example below.. If I do this now, passFilter does not get called.
On https://recastnav.com/classdtQueryFilter.html is mentioned "DT_VIRTUAL_QUERYFILTER must be defined in order to extend this class."

class CustomFilter extends QueryFilter {

constructor() {
    super();
}

passFilter(polyRef: number, tile: any, poly: any): boolean {
    console.log(polyRef, tile, poly)
    
    if (poly.get_area() === 63) {
        return false;
    }
    return poly.get_flags() !== 0;
    //return (poly->flags & m_includeFlags) != 0 && (poly->flags & m_excludeFlags) == 0;
    //return super.passFilter(polyRef, tile, poly);
}

}

[isaac-mason]

Hi, this is something that could be exposed with emscripten's webidl binder using JSImplementation. I'd accept a PR for this, but it's worth noting that the performance of wasm -> javascript callbacks is not good, this will quickly make this impractical to use for game or simulation use cases where nav mesh querying is frequent and must be fast.

[lukasvdelft]

Thanks for the fast response. Yes, I understand the performance implications (wasm-js), but we use this/your port for what we call our Studio env, this is where we prepare and manage venues/buildings for vps-based navigation. I would like to do some ETA route testing in this env as well, just to make sure things work (also irt dynamic obstacles for which i would rather not use the tile-cache, hence the passFilter requirement). We use the navmesh export output in different platforms (Unity, Android, IOS), it is in these platforms that the performance of the callback really matters (but those implementations will not have a wasm-js thing).

In "recast-navigation.idl" I already see an almost complete interface def (getCost is there but commented-out, passFIlter is only part missing). If I complement that, and add the JSImplementation (I have "DebugDraw" as example), will that be the only thing? And how about the "DT_VIRTUAL_QUERYFILTER" property, how will/can that be set?

[lukasvdelft]

Made some changes to idl (see below), had to add "add_definitions(-DDT_VIRTUAL_QUERYFILTER)" to CMakeLists.txt. I also addedd "passFilter" def to nav-mesh-query.ts" (Core) Then it builds nicely and the definitions are recognized in the client, but the passFIlter method from my subclassed filter still isn't called .. and furthermore the debugdrawer stops working. If you have a clue why these things happen let me know. This is rather new territory for me.

interface dtQueryFilter {
    void dtQueryFilter();

    float getCost([Const] float[] pa, [Const] float[] pb,
                            [Const] unsigned long prevRef, [Const] dtMeshTile prevTile, [Const] dtPoly prevPoly,
     			     [Const] unsigned long curRef, [Const] dtMeshTile curTile, [Const] dtPoly curPoly,
    	 	             [Const] unsigned long nextRef, [Const] dtMeshTile nextTile, [Const] dtPoly nextPoly);

    boolean passFilter([Const] unsigned long ref, [Const] dtMeshTile tile, [Const] dtPoly poly);

    float getAreaCost([Const] long i);

    void setAreaCost([Const] long i, [Const] float cost);

    unsigned short getIncludeFlags();

    void setIncludeFlags([Const] unsigned short flags);

    unsigned short getExcludeFlags();

    void setExcludeFlags([Const] unsigned short flags);
};

[JSImplementation="dtQueryFilter"]
interface dtQueryFilterImpl {
    void dtQueryFilterImpl();

    float getCost([Const] float[] pa, [Const] float[] pb,
	 			  [Const] unsigned long prevRef, [Const] dtMeshTile prevTile, [Const] dtPoly prevPoly,
	 			  [Const] unsigned long curRef, [Const] dtMeshTile curTile, [Const] dtPoly curPoly,
	 			  [Const] unsigned long nextRef, [Const] dtMeshTile nextTile, [Const] dtPoly nextPoly);
    
    boolean passFilter([Const] unsigned long ref, [Const] dtMeshTile tile, [Const] dtPoly poly);
    
    float getAreaCost([Const] long i);
    
    void setAreaCost([Const] long i, [Const] float cost);
    
    unsigned short getIncludeFlags();
    
    void setIncludeFlags([Const] unsigned short flags);
    
    unsigned short getExcludeFlags();
    
    void setExcludeFlags([Const] unsigned short flags);
};

[isaac-mason]

Sorry, I missed the update on this issue. If you can create a PR with what you have I'd be happy to take a look.

[isaac-mason]

Alternatively, you may consider trying out the alpha of navcat, which has better support for custom query filters, that will be fast too (as navcat isn't a wasm library).

https://github.com/isaac-mason/navcat/blob/main/examples/src/example-custom-areas.ts#L61

[isaac-mason]

Oh I just re-read this:

We use the navmesh export output in different platforms (Unity, Android, IOS), it is in these platforms that the performance of the callback really matters (but those implementations will not have a wasm-js thing).

If you are using recast c++ on these other platforms navcat isn't an interesting option for you. But if you are using a javascript / a webview this would be interesting.

[lukasvdelft]

Hi Isaac, your comments are so spot on! As I didn't get the subclassing of the Filter working (memory problems on C++ side) I wrote partly our own path-finding client extensions in TypeScript, exactly as you did in navcat. We can use this in webviews on Swift/Android but still not in Unity (problem 1). And it also lacks a dynamic obstacles mechanism like in https://github.com/recast4j/recast4j/tree/main/detour-dynamic OR https://arongranberg.com/astar/docs_dev/navmeshcutting.php (problem2).
We don't want to use tilecache as we have very large sites and the precision is less than tiled-navmesh. We are considering writing our own C++ lib for pathfinding and use that in all envs (or indeed even use typescript within Unity, single threaded..). This throws in the output of the navmesh generation challenge, we need a format that we can work with everywhere (like the export does in your wasm port). So I have a few questions for you:
1] what is your vision on dynamic obstacles (we are considering using the flags mechanisms but of course this is less precise as the triangles can extend beyond the borders of the obstacles)
2] what is your vision in export formats (we could use the WASM export output for instance in the c# port of ikpil)
3] in general what approach would you suggest (as you are very knowledgable on the topic)
4] are you open for a short call sometime? we might possible be interested in joined efforts (like maintaining a shared repo)
If I ask too much, I understand, you will be busy. Either way, I do respect your work very much.