GetBoundingBox() plane-oriented but world coordinates

Scripting
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1

Two overloads here:

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If I just use obj.GetBoundingBox(plane), it uses the second overload, and I get the box output in plane coordinates. I would like the first, the plane-oriented bounding box, but in world coordinates… How to?

2

Hi Mitch,

Does this help?

SampleCsBoundingBox.cs

– Dale

3

Hi Mitch,

I used your script to move objects to origin, it works great! Do you know of any scripts for automating the Make2D to generate Section Views?

4

Hi Dale,

I don’t do C# - but… I see you first need to get the transform (xform) from World XY to the desired plane, then use GetBoundingBox(xform), then transform the results back from the plane to World XY …

I don’t understand why there isn’t an overload in the method to do the above forward/reverse transform automatically? It would seem this would be a pretty common thing to want - the plane oriented bounding box but with the results in world coordinates.

1 Like
5

Hi Mitch,

Does this do what you’re looking for?

import rhinoscriptsyntax as rs
from scriptcontext import doc
from Rhino.Geometry import Plane, Box

import clr
oBox = clr.Reference[Box]()

b = SomeBrep()
p = SomePlane()

bb = b.GetBoundingBox(p, oBox)
box = oBox.Value
doc.Objects.AddBox(box)
rs.Redraw()
6

Hi Alain,

Thanks for the sample, no, it doesn’t unfortunately. While it shows me the way to use the overload, I guess I misunderstood what that overload outputs… It’s not what I expected.

In the file below, there is an off-axis rectangle and I want to get the center of its bounding box relative to the curve plane and add a point there (the point in the file is the plane-aligned bb center, locked for reference).

TestBBRect.3dm (2.2 MB)

This does not work:

import rhinoscriptsyntax as rs
import Rhino, clr

def TestPlaneOrientedBB():
    obj_id=rs.GetObject("Pick rectangle",4,preselect=True)
    if obj_id:
        crv=rs.coercecurve(obj_id)
        rc,plane=crv.TryGetPlane()
        if rc:
            wxy=Rhino.Geometry.Plane.WorldXY
            plane.Origin=crv.PointAtStart
            oBox = clr.Reference[Rhino.Geometry.Box]()
            bb=crv.GetBoundingBox(plane,oBox)
            rs.AddPoint(bb.Center)
TestPlaneOrientedBB()

This does (forward/reverse transformation):

import rhinoscriptsyntax as rs
import Rhino

def TestPlaneOrientedBB():
    obj_id=rs.GetObject("Pick rectangle",4,preselect=True)
    if obj_id:
        crv=rs.coercecurve(obj_id)
        rc,plane=crv.TryGetPlane()
        if rc:
            wxy=Rhino.Geometry.Plane.WorldXY
            plane.Origin=crv.PointAtStart
            out_xform=Rhino.Geometry.Transform.ChangeBasis(wxy,plane)
            bb=crv.GetBoundingBox(out_xform)
            #rs.AddPoint(bb.Center)
            in_xform=Rhino.Geometry.Transform.ChangeBasis(plane,wxy)
            new_pt=rs.PointTransform(bb.Center,in_xform)
            rs.AddPoint(new_pt)
TestPlaneOrientedBB()
7

@Helvetosaur is looking for the RhinoCommon equivalent of this:

https://developer.rhino3d.com/api/rhinoscript/geometry_methods/boundingbox.htm

– Dale

8

Yes, finally I just made my own function:

def GetPlaneAlignedBBCtr(obj,plane):
    wxy=Rhino.Geometry.Plane.WorldXY
    out_xform=Rhino.Geometry.Transform.ChangeBasis(wxy,plane)
    bb=obj.GetBoundingBox(out_xform)
    if bb:
        in_xform=Rhino.Geometry.Transform.ChangeBasis(plane,wxy)
        return in_xform*bb.Center