A* Pathfinding Project

GetContours not closing correctly


#1

While using the GetContours function I noticed that there was 2 points too much in the list.
I was able to visualize this as next:
Lines are being drawn from the center to each Contour point


close up:
image

Code used:
public List<Vector3> segments = new List<Vector3>();

    public override void OnPostScan()
    {
        if (AstarPath.active.graphs.Length == 0)
            return;
        
        // Get the first graph
        NavGraph navmesh = AstarPath.active.graphs[0];
        if (navmesh == null)
            return;
        
        segments = GraphUtilities.GetContours(navmesh);
    }
    
    private void OnDrawGizmos()
    {
        if (segments == null || segments.Count == 0)
            return;

        for (int i = 0; i < 8; i++)
        {
            Debug.DrawLine(segments[i], Vector3.zero, Color.red, 1);
        }
    }

#2

After doing some closer investigation it looks like the First point is added 4 times int total ( only 2 times expected )

order of corners being added visualized from bottom to top:


Split corner from previous pictures is top right in this picture

Modified Code:
public List<Vector3> segments = new List<Vector3>();

    public override void OnPostScan()
    {
        if (AstarPath.active.graphs.Length == 0)
            return;
        
        // Get the first graph
        NavGraph navmesh = AstarPath.active.graphs[0];
        if (navmesh == null)
            return;
        
        segments = GraphUtilities.GetContours(navmesh);
    }
    
    private void OnDrawGizmos()
    {
        if (segments == null || segments.Count == 0)
            return;

        for (int i = 0; i < 10; i++)
        {
            Debug.DrawLine(segments[i], Vector3.zero + new Vector3(0,i,0), Color.red, 1);
        }
    }

#3

Hi

Thank you for reporting this.
This has already been fixed in the 4.3 beta.

Here is an excerpt from the changelog:

Pathfinding.GraphUtilities.GetContours for grid graphs now simplifies the contour more consistently. Previously there could be one or two additional points where the algorithm started to traverse the contour.


#4

My bad should have checked.
Thanks I’ll try it tomorrow :slight_smile:


#5

Verified that it works as expected. Thanks