Box to C# component

[Petras1 (Petras Vestartas)]

Hi,

How do you reference OBB (oriented bounding-box) to Grasshopper, Python or C# editor?
It is always casted to World aligned Bounding Box:

[DanielPiker]

See also this previous discussion:

BoundingBox forced to be converted to Box

Ummm, since GH native BoundingBox seems to produce a Box instead of a BoundingBox, I made a simple Python script that gives a BoundingBox. But still there is the same problem. The BoundingBox is a BoundingBox inside the Python node, but it becomes a Box once it’s output from the Python node. Does anybody knows a solution? Thank you.

[Joseph_Oster]

You didn’t post any code?

Do you have the OOB plane?

https://developer.rhino3d.com/api/RhinoCommon/html/M_Rhino_Geometry_GeometryBase_GetBoundingBox.htm

This recent thread was about finding minimal bounding box but only considered rotation of ‘World XY’ about its Z axis. Your geometry needs more than that.

INQUIRE: Bounding box control points behavior

Wow! Of course, that Parallel.For() loop helps too, eh? Two of them! The Nurbs curves look very weird though, better to use the DeBrep ‘E’ (Edges). Or PLine (Polyline) with inverted ‘C’ (Closed) input. P.S. This ‘out worldXY_bbox’ is interesting too? BoundingBox pln_bbox = crv[i].GetBoundingBox(planes[j], out worldXY_bbox); As we discussed in PMs, that returns actual box geometry, though the distinction is still fuzzy for me. https://developer.rhino3d.com/api/RhinoCommon/html/M_Rhino_Ge…

[Petras1 (Petras Vestartas)]

Sorry, I think I did not describe the problem correctly.

If I try to input to C# component a Brep that looks like a box as a Box type.
The brep boundingbox is computed, instead of casting it to a Box type.
Is there a way to cast Brep to Box type that remains the OBB?

[diff-arch]

Hi Petras,

Check out this topic of mine:

Get plane-aligned flatbox of a triangular mesh face in GHPython?

Hi, I’m purposfully trying to get the plane-aligned flatbox (bounding box of no volume) of a triangular mesh face. This turned out to be far more challenging than expected! import Rhino.Geometry as rg def get_face_edges(face_vertices): """Returns edges as lines for a list of face vertices.""" edges = [] for i in range(len(face_vertices) - 2): edges.append(rg.Line(face_vertices[i], face_vertices[i + 1])) edges.append(rg.Line(face_vertices[-1], face_vertic…

I believe you have encountered a similar problem.

[Joseph_Oster]

@Petras1

If I try to input to C# component a Brep that looks like a box as a Box type.
The brep boundingbox is computed, instead of casting it to a Box type.
Is there a way to cast Brep to Box type that remains the OBB?

        Box worldXY_bbox;
        BoundingBox pln_bbox = srf[i].GetBoundingBox(pln, out worldXY_bbox);
        double ar = worldXY_bbox.Area;
        if(ar < area){
          area = ar;
          nb[i] = worldXY_bbox;
        }

[Petras1 (Petras Vestartas)]

@Joseph_Oster

        Box worldXY_bbox;
        BoundingBox pln_bbox = srf[i].GetBoundingBox(pln, out worldXY_bbox);
        double ar = worldXY_bbox.Area;
        if(ar < area){
          area = ar;
          nb[i] = worldXY_bbox;
        }

Thanks, this suggested me the right solution:

    Box x = Box.Unset;
    Plane xPlane = Plane.Unset;
    bx.Surfaces[0].FrameAt(0, 0, out xPlane);
    bx.GetBoundingBox(xPlane, out x);

I wish there would be a direct casting, but this works.

[Petras1 (Petras Vestartas)]

Thank you;)

[Joseph_Oster]

@Petras1

Thanks, this suggested me the right solution:

That C# code was from Riccardo (@maje90) in the thread I mentioned earlier. It was part of a ‘Parallel.For()’ loop to speed up the search for OBB. In the “C# V4” cyan group, BBoxV5_Aug1a.gh

INQUIRE: Bounding box control points behavior

Hi all! A small fix that we can do is to let curve enters the c# script. There was like 400ms wasted to convert the curves to brep because of the input type hint. Done that… but I wasn’t able to measure the difference in execution. Currently the c# does the job in 20ms on my pc… Maybe the BBox calculation is much heavier if done on surfaces/brep objects. See the bottom/last script. BBoxV5_Aug1a.gh (215.8 KB)

Nice work, good thread. Makes C# interesting.