Passing of data through the Structures between different GHA components

Hi David, Steve and others!

I am looking the way how can I pass the data from one GHA component (as output) to the other GHA component (as input) using structures.

Example of structure should look like this:

Private Structure MD
    'Declare data members
    Dim a As Double
    Dim b As Double
    Dim c As Double
    Dim d As string
    Dim e As String
End Structure

Registering of the output (in the first component) is done in the following way:

...

pManager.Register_GenericParam("temp", "tempdims","Output")

...

Dim result As New MD

result.a=...

result.b=...

result.c=...

...

DA.SetData(0,result)

Registering of the input (in the second component) is done in the following way:

pManager.AddGenericParameter("temp", "tempdims","Input of dims",GH_ParamAccess.item)

...

Dim MDA As Object=Nothing

If (Not DA.GetData(0, MDA)) Then Return

Dim MDA1 As MD=DirectCast(MDA,MD)

Same structure (MD) is defined in the second component as private type.

While doing the casting with DirectCast I got an error that "Cast method is not valid".

How can I solve the issue?

Should I really define same structure in both components or is there any easier way?

If not, how to perform the right casting?

Thank you in advance!

Kind regards,

Dmitriy

Replies to This Discussion

Permalink Reply by David Rutten on March 17, 2013 at 8:08am

All data that is shared between components through wires has to implement the IGH_Goo interface.

What usually happens is that a wrapper class is written for a specific data type (such as System.Int32 or System.String or Rhino.Geometry.Curve) which provides all IGH_Goo required methods and properties for a single instance of that type.

You can use GH_ObjectWrapper to encapsulate your struct, but GH_ObjectWrapper is a last ditch attempt at providing IGH_Goo functionality, it's typically better if you specifically implement IGH_Goo for your type.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Dmitriy Sonechko on March 17, 2013 at 10:50am

Hi David,

Thanks for prompt reply.

As I understood - new class that inherits GH_Goo(of MD) should be used.

Will it be possible to use GH_Goo if I need to include complicated objects like Brep or Surface?

I have looked through the forum and have found few things that can help me to move further to develop my own type, however is it possible to provide a simple example of setting up a custom type in VB?

Appreciate a lot!

Thanks,

Dmitriy

Permalink Reply by David Rutten on March 17, 2013 at 11:36am

The SDK help files have a topic on deriving from GH_Goo(Of Integer). You can start there.

David Rutten

david@mcneel.com

Poprad, Slovakia

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