Selecting the Topmost Group on Mouse Click in Grasshopper Canvas

Grasshopper Developer
, ,
1

Hi everyone,

I’m currently trying to get the topmost group from a mouse click event in Grasshopper. Here’s what I have so far:

var groupsAtCursor = canvas.Document.Objects
    .Where(obj => obj.Attributes.Bounds.IntersectsWith(toleranceRect))
    .OfType<GH_Group>()
    .ToList();

This gives me all the groups under the cursor. However, what I actually need is the group that is visually on top, i.e., the one with the highest Z-order.

I couldn’t find an attribute like ZIndex or anything similar on GH_DocumentObject.Attributes or elsewhere. Am I missing something? Is there a recommended way to determine which object is drawn on top?

Any suggestions or alternative approaches would be appreciated!

Thanks in advance!

2

Aren’t Document.Objects already sorted by the render order (items in the back come first, in the front come last)?

3

I did not check on that yet, but this way got me quite reliable results.

    public static T FindDocumentObjectAtMousePosition<T>(GH_Canvas canvas, MouseEventArgs e)
        where T : class, IGH_DocumentObject
    {
        var canvasEvent = new GH_CanvasMouseEvent(canvas.Viewport, e);
        var attribute = canvas.Document.FindAttribute(canvasEvent.CanvasLocation, false);
        return attribute?.DocObject as T;
    }