Custom Display in Component - An error occured in the display pipeline

I am drying to produce a custom preview for a component.

Therefor I did change the to Subs DrawViewportWires and DrawViewportMeshes.

When using the component, Rhino will write:

An error occured in the display pipeline @ xx:xx:xx(xxxms)

iThe DrawViewportWires only when loaded!

The DrawViewportMeshes always when the viewport is refreshed!

Any Idea?

Public Overrides Sub DrawViewportWires(ByVal args As Grasshopper.Kernel.IGH_PreviewArgs)
' MyBase.DrawViewportWires(args)-> Disabled because nothing to Display
If (Hidden) Then Return

For Each item As Rhino.Geometry.Circle In Circle
args.Display.DrawCircle(item, GC, 3)
Next

For Each item As Rhino.Display.Text3d In txt

args.Display.Draw3dText(item, GC)
Next

End Sub

Public Overrides Sub DrawViewportMeshes(ByVal args As Grasshopper.Kernel.IGH_PreviewArgs)
' MyBase.DrawViewportMeshes(args) -> Disabled because nothing to Display
If (Hidden) Then Return

Dim Brep As Rhino.Geometry.Brep
Dim M As Rhino.Display.DisplayMaterial

For i As Integer = 0 To Circle.Count
Brep = Rhino.Geometry.Brep.CreatePlanarBreps(Circle.Item(i).ToNurbsCurve())(0)
M = New Rhino.Display.DisplayMaterial(VC.Item(Math.Min(i, VC.Count - 1)))
args.Display.DrawBrepShaded(Brep, M)
Next

End Sub

Replies to This Discussion

Permalink Reply by David Rutten on August 1, 2012 at 9:41am

Hi Richard,

have you set up your project so you can debug into it? If so, put a breakpoint on the first lines in DrawViewportMeshes and DrawViewportWires and step through the code until it fails.

Things that might be causing the error are (at first sight):

Circle is a null-reference
txt is a null reference
For i As Integer = 0 To Circle.Count should probably be ...To Circle.Count-1

Also, it's not a good idea to perform heavy computation inside the drawing routines. CreatePlanarBreps, ToNurbsCurve etc. all take a lot of cycles and you should cache or pre-compute the results. This will make it go much faster.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Richard Schaffranek on August 1, 2012 at 10:05am