Bounding Box of Grasshopper Preview

Hy Guys, I'm working on a script which should get the Bounding Box of all Grasshopper Previews.

Is this possible without baking ?? And is it possible to get all control points of the previewed breps, lines, points, curves, ... ??

I haven't seen something like this in the forum so I have opened a new discussion.

Thanks for all your help.

Nice Greets

Alex

Replies to This Discussion

Permalink Reply by David Rutten on January 23, 2013 at 11:32am

There's no method for this. The GH_Document does retain a BoundingBox which it uses as clipping box during redraws, but this is a private field that has not been exposed as a public property.

What you need to do is iterate over all IGH_DocumentObjects in the document, see which objects implement the IGH_PreviewObject interface, cast them and aggregate all the ClippingBoxes. In VB:

Dim clipBox As BoundingBox = Rhino.Geometry.BoundingBox.Empty

For Each obj As IGH_DocumentObject in doc.Objects

Dim prvObject As IGH_PreviewObject = TryCast(obj, IGH_PreviewObject)

If (prvObject Is Nothing) Then Continue For

If (Not prvObject.IsPreviewCapable) Then Continue For

If (prvObject.Hidden) Then Continue For

clipBox.Union(prvObject.ClippingBox)

Next

Note that this will usually give you fast boundingboxes, not accurate ones. As for control-points, that's a lot harder. Why do you care about the control-point clipping box for all Grasshopper geometry?

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Alexander Greil on January 23, 2013 at 1:34pm

Thanks David.

I want to place a Camera and always "look" at the last placed object from my definition. And therefore I was thinking, that always looking at one of the control points of the last object.

But it will be much easier to look at the BoundingBox.Center, or ?

Permalink Reply by David Rutten on January 23, 2013 at 3:27pm

Rhino zooming works with boundingboxes so you could presumably use the boundingbox to set both target and zoom factors. The problem will be how to detect what the last object was and when exactly to focus on its preview geometry. I can't see a solution that will consistently work.

David Rutten

david@mcneel.com

Poprad, Slovakia

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