Issue with LayerGridGraph partial updates wrong on remove/re-add

General Grid graph
1
  • A* version: 5.4.5
  • Unity version: 2022.3.62f

I have a layered gridgraph and a game where you can build in multiple floors.

Whenever something is put down I use the bounds to do a graph update to scan the new area.

AstarPath.active.UpdateGraphs( GetExpandedWorldBounds( extendNodes ) );

Here’s the scenario:

  • put a tower → 4 nodes on top of the tower appear correctly - everything works
  • remove the tower → 4 nodes disappear
  • put the tower back in exactly the same spot → 4 nodes come back but the connections are wrong
    • most connections from the new nodes are gone, sometimes (not always!) the connections between the new nodes, sometimes from new to existing nodes
    • if i remove again, and then add again, then different set of connections are wrong
  • I can re-update the bounds and it stays wrong
    • the nodes get processed, but the connections stay wrong
    • even doing a very wide area around the location doesn’t fix it

Visualized:
I just added, removed & readded the same platform twice.
I visualize the node (white plane) and unavailable connections (red line).

[1] First time: 4 nodes, no red connections.

image
image277×188 75.6 KB

[2] Second time: red connections added for the non-existing nodes. I have not figured out how yet but the grid api returns different data. I suspect there might be some node records present for the non-existing nodes now.

image
image273×159 66.7 KB

[3] Third time: different connections are bad, now effectively my agent cannot move across those nodes anymore.

image
image247×139 54 KB

If I keep removing and adding, i loop between 2 and 3 all the time. Connections are inversed?

The only thing that fixes it is doing a full scan on the graph. Then everything is as expected.
Is it possible some residual info is kept somewhere that is only cleared on a full rescan?

2

Would you mind posting your code for how you’re getting your world bounds? That GetExpandedWorldBounds() method, if you don’t mind. Going to recreate this on my end to do some digging.

3

Sure, this is the relevant code:

/// <summary>
/// Get the world bounds expanded with a number of nodes.
/// This will extend in the xz direction but leave the height as is.
/// </summary>
public Bounds GetExpandedWorldBounds( int extendNodes ) {
	// Calculate axis-aligned bounding box in world space
	var matrix = Matrix4x4.TRS( transform.position, transform.rotation, Vector3.one );
	var worldCenter = matrix.MultiplyPoint3x4( Vector3.zero );
	var worldSize = matrix.MultiplyVector( size );

	var bounds = new Bounds( worldCenter, AbsVec( worldSize ) );
	if ( extendNodes > 0 ) {
		bounds.Expand( new Vector3( GameGrid.TileSize, 0, GameGrid.TileSize ) * 2 * extendNodes );
	}

	return bounds;
}

private Vector3 AbsVec( Vector3 v ) => new Vector3( Mathf.Abs( v.x ), Mathf.Abs( v.y ), Mathf.Abs( v.z ) );
4

So I tried to replicate this in a clean project with no success. Would you be able to send over a project that demonstrates this? If you can get it to happen in a clean project that would be helpful.