Question

How I can obtain the bounding box of a curve object based on a reference plane using VB.NET?

Answer

Use the RhinoGetTightBoundingBox SDK function. By default, this function will compute the bounding box of an array of objects in world coordinates. But, if you specify the optional "plane" argument, the bounding box will be computed based on that plane.

Example

The following example code demonstrates how to calculate the bounding box of a curve object based on a reference plane.

Request

Please add c# version.

  ' Select a curve object
  Dim go As New MRhinoGetObject
  go.SetCommandPrompt("Select curve")
  go.SetGeometryFilter(IRhinoGetObject.GEOMETRY_TYPE_FILTER.curve_object)
  go.GetObjects(1, 1)
  If (go.CommandResult() <> IRhinoCommand.result.success) Then
    Return go.CommandResult()
  End If


  ' Validate selection
  Dim obj As IRhinoObject = go.Object(0).Object()
  If (obj Is Nothing) Then
    Return IRhinoCommand.result.failure
  End If


  ' Get the active view
  Dim view As MRhinoView = RhUtil.RhinoApp.ActiveView()
  If (view Is Nothing) Then
    Return IRhinoCommand.result.failure
  End If


  ' Get the active view's construction plane
  Dim plane As New OnPlane(view.ActiveViewport().ConstructionPlane().m_plane)


  ' Compute the tight bounding box of the curve based on the 
  ' active view's construction plane
  Dim bbox As New OnBoundingBox
  Dim objs(0) As IRhinoObject
  objs(0) = obj
  Dim rc As Boolean = RhinoGetTightBoundingBox(objs, bbox, False, plane)
  If (rc = False) Then
    Return IRhinoCommand.result.failure
  End If


  ' Print the min and max box coordinates in world coordinates
  Dim min As On3dPoint = bbox.Min()
  Dim max As On3dPoint = bbox.Max()
  RhUtil.RhinoApp.Print(String.Format("World min: {0},{1},{2}" + vbCrLf, min.x, min.y, min.z))
  RhUtil.RhinoApp.Print(String.Format("World max: {0},{1},{2}" + vbCrLf, max.x, max.y, max.z))


  ' Create a world to construction plane transformation
  Dim world_to_plane As New OnXform
  world_to_plane.ChangeBasis(plane, OnUtil.On_xy_plane)


  ' Transform the bounding box
  bbox.Transform(world_to_plane)


  ' Print the min and max box coordinates in cplane coordinates
  min = bbox.Min()
  max = bbox.Max()
  RhUtil.RhinoApp.Print(String.Format("CPlane min: {0},{1},{2}" + vbCrLf, min.x, min.y, min.z))
  RhUtil.RhinoApp.Print(String.Format("CPlane max: {0},{1},{2}" + vbCrLf, max.x, max.y, max.z))