When the game world is empty why does recast graph error?

#1

So i start the game with an empty world as intended. But the code simply errors straight away:

DivideByZeroException: Division by zero
Pathfinding.RecastGraph.ScanAllTiles (.OnScanStatus statusCallback) (at Assets/AstarPathfindingProject/Generators/RecastGenerator.cs:1115)

I have scan on Awake encase the world isn’t empty to start with - it varies. But i am pretty sure it should not error but simply not create a graph…

I’m not using tiles for my Recast graph if that makes much difference… using tiles how ever does stop the error so its something to do with not using tiles :frowning:

#2

Hi

That sounds bad.
Scanning an empty graph works perfectly fine for me, so maybe it is something I have fixed in a dev version.
Can you check what code is at that line? (the line numbers differ between versions, so it is hard to know which line you mean).

#3

@aron_granberg

Hey the error occurs in

Script: 
ReCastGenerator.cs  

Method:
protected void ScanAllTiles (OnScanStatus statusCallback) {

Line:
//Number of tiles
int tw = (gw + tileSizeX-1) / tileSizeX; // here

If it helps, i request to re-scan the world using these 3 lines:

void Start(){
AstarPath.active.astarData.recastGraph.forcedBoundsSize = worldSize;
AstarPath.active.astarData.recastGraph.SnapForceBoundsToScene();
AstarPath.active.Scan();
}

I also get this warning prior to the error:
No MeshFilters were found contained in the layers specified by the 'mask' variables

But the mesh filter warning is to be expected given the world is empty at Start.

#4

Ok, seems like the bounds set for your graph might have been smaller than a single voxel.
I have fixed this in my dev version now, thanks for reporting the bug.

#5

I’m not sure if i misunderstand but my default bounds are pretty large before the game starts. Here is my settings perhaps there something i have set that might highlight the problem.

#6

When will the dev version be released as i can’t compile my game at the moment due to this error.

#7

Hi

You are using

AstarPath.active.astarData.recastGraph.SnapForceBoundsToScene();

Since there is nothing in the scene, I suspect that will set the bounds to have a zero size. Make sure it has a non-zero size (at least as large as a voxel or two) to work around the issue.

#8

Okay yeah that solved it thanks ! :slight_smile:

If i am manually setting an area for the Recast like this:

    AstarPath.active.astarData.recastGraph.forcedBoundsCenter = new Vector3(0f, 0f, 0f);
    AstarPath.active.astarData.recastGraph.forcedBoundsSize = new Vector3(10f, 0f, 10f);
    AstarPath.active.astarData.recastGraph.SnapForceBoundsToScene(); //is this needed?
    AstarPath.active.Scan();

Is the snap force method still required here? As i’m unclear what the method does the documentation doesn’t have a description for it.

It seems to work without the method just wanted to make sure.

#9

Hi

TL;DR, no you should not call it.

Ah, it does indeed seem like that method does not have any documentation. I have added some in my local dev version.

/** Changes the bounds of the graph to precisely encapsulate all objects in the scene that can be included in the scanning process based on the settings.
* Which objects are used depends on the settings. If an object would have affected the graph with the current settings if it would have
* been inside the bounds of the graph, it will be detected and the bounds will be expanded to contain that object.
* For example if #rasterizeMeshes is set to true, the bounds will be changed to contain all meshes which are in a
* layer included in the #mask or in the #tagMask or have a RecastMeshObj component attached to the same GameObject.
*
* This method corresponds to the 'Snap bounds to scene' button in the inspector.
*
* \see rasterizeMeshes
* \see rasterizeTerrain
* \see rasterizeColliders
* \see mask
* \see tagMask
*
* \see forcedBoundsCenter
* \see forcedBoundsSize
*/
#10

Ah okay thanks good to know :slight_smile: Everything is working again now.

1 Like