Finding an object center

Scripting
1

using VBscript, how can I find an object’s center similar to Gumball. I can’t seem to find a command or group of commands that will do this.

2

For the Gumball, the object’s center is the center of its bounding box. So you could write a custom function to get an object’s bounding box center something like this:

Private Function BBCtr(obj)
    BBCtr=Null
    Dim arrBB
    arrBB=Rhino.BoundingBox(obj)
    If IsArray(arrBB) Then
        BBCtr=Rhino.PointDivide(Rhino.PointAdd(arrBB(0),arrBB(6)),2)
    End If    
End Function

–Mitch

1 Like
3

If you don’t wanna mess with Rhino.BoundingBox, there’s:

Rhino.CurveAreaCentroid
Rhino.MeshAreaCentroid
Rhino.SurfaceAreaCentroid

Curve Area Centroid is bugged though. Sometimes it will fail for no apparent reason.

4

Yes. However, if you are trying to get the same center as Gumball, only the bounding box is guaranteed.

Pasted image1243×858 73.6 KB

5

Interesting! Why wouldn’t they match in this example though (assuming it’s a rectangular box with box cutout)?..

6

Because the volume centroid is a mean (average) of all the enclosed volume space - which is naturally weighted towards the lower left rear in this case - whereas the bounding box center does not take into account the object’s shape, volume or other characteristics, just its overall size relative to the world or local CPlane.

–Mitch

7

Hi Mitch,

Thanks for your help.
Just what I needed.

8

Hi Asterisk,

Thanks for your help.

Mitch’s suggestion matches more closely what I needed.

Still learned much from your help.