# Snap to gumball center or bounding box center of (poly-)curves

Hi All

Is it somehow possible - or can it be added to the wishlist - to snap to the center of a closed (poly-)curve? I’ve noticed that I can snap to the center of closed polylines, but not closed curves or polycurves. Is there a mathematical /NURBS/other reason why, or is it one of those “because someone said so”-things?

TIA, Jakob

Hm. Based on the fact that the center of a triangle can be calculated by adding the points together and the dividing the result, that may work also if you do the same for the end points of a polyline?

I haven’t tried it, so I might be wrong.

Edit: This is what I get:

Fig. Shift with Wrap set to false reduces the number of vertices by one, so that start and end doesn’t add one vertice too much. Ex: Triangle has three corners, not four, etc.:

// Rolf

I’m still not sure of if the center point is valid for concave shapes. Perhaps only convex polygons gets it right(?) I guess someone else out there knows this better.

// Rolf

Hi Jakob - I believe this works on polylines and curves that could be polylines (e.g. change a polyline to degree 2 and don’t monkey with any points) because it is a ‘fake’ center - it is an average of all the vertex locations - cheap and quick to calculate on the fly… it is not the same, necessarily as the area centroid of the polyline.

-Pascal