Beginner rhino C++ Plugin question - What is a Document in Rhino?

Rhino Developer
1

Hi, So I am exploring C++ by getting started in Rhino Plugin development. I have successfully configured visual studio and have made a basic “hello-world” plugin in Rhino. What I would like to know is what is the context variable all about and what is a Rhino Document, how do I get access to it? Can I use it to get information about the objects, materials, etc?

2

Hi Alex,

A context, or CRhinoCommandContext provides information on how the command was run by the user (either interactive or scripted). It also contains a reference to the active document, or CRhinoDoc object.

For example:

CRhinoCommand::result CCommandTest::RunCommand(const CRhinoCommandContext& context)
{
  if (context.IsInteractive())
  {
    // Show some dialog interface
  }
  else
  {
    // Show a command line interface
  }

  // Access the active document (for example)
  context.m_doc.Redraw();

The document, or CRhinoDoc, holds everything that is saved to 3dm files.

– Dale

1 Like
3

Hi @dale,
Thank you so much for your helpful replies on both my posts :smile:
This was really helpful. Though, I do have further questions, which I do hope you could give me some clarification about?

  1. When/Why exactly do I need to call the Redraw() method if I am just getting the attributes of the objects present in the document?
  2. Also, where can I find the all the objects present in the document from the CRhinoDoc. I am aware that I can get objects using the objectIterator and using Layers. But, is it possible to get them through the CRhinoDoc and get its geometry and attributes data?
4

You don’t. It’s just an example of access the document from a command.

An object iterator walks the object list in the document for you.

For example:


CRhinoCommand::result CCommandTest::RunCommand(const CRhinoCommandContext& context)
{
  // Create an object iterator to process non-deleted objects that are stored in the active document.
  CRhinoObjectIterator it(CRhinoObjectIterator::undeleted_objects, CRhinoObjectIterator::active_objects);
  it.IncludeLights();
  
  const CRhinoObject* rhino_object = nullptr;
  for (rhino_object = it.First(); nullptr != rhino_object; rhino_object = it.Next())
  {
    const ON_Geometry* geometry = rhino_object->Geometry();
    if (nullptr != geometry)
    {
      const CRhinoObjectAttributes& attributes = rhino_object->Attributes();
      // TODO...
    }
  }

  return CRhinoCommand::success;
}

– Dale

1 Like
5

Hello @dale, thank you for the prompt reply.

Oh okay, I was somehow under the impression that the document had some sort of data structure to hold all the objects. I now get that I should be using the object iterator.

Also, can I use the object Iterator to get the NamedViews in the document too right? I did not find anything in the docs regarding that, so am I on the right path?

Finally, I have a doubt regarding the materials. Should I get the materials of the current document by using

context.m_doc.m_material_table

and store all the material data as I require? Is this the correct way to get material data correctly when exporting 3dm to another custom file format? And also, how do I associate which object is using which material?
Should I be using the m_material_index and searching it on the material table to find out? :

const CRhinoObjectAttributes& attributes = currentRhinoObject->Attributes();

attributes.m_material_index;

6

Named views are stored in the document’s properties, or CRhinoDocProperties, member.

int i = 0;
const ON_3dmView* view_3dm = nullptr;
while (nullptr != (view_3dm = context.m_doc.Properties().NamedView(i)))
{
  RhinoApp().Print(L"%s\n", static_cast<const wchar_t*>(view_3dm->m_name));
  i++;
}

Yes. You can also just call CRhinoObject::ObjectMaterial().

– Dale

1 Like
7

Hey @dale, thank you for your prompt reply and help!