Adding Clipping Plane Objects

Developer: C++
Summary: Demonstrates how to add a viewport clipping plane object using the Rhino 4.0 SDK.

I would like to write a command to add clipping planes to a viewport so that I can easily cut sections of the model. I have seen the CRhinoClippingPlaneObject class, but I am not sure how to use it. Could I see an example?

The following sample code demonstrates how to add a viewport clipping plane object.

 
CRhinoCommand::result CCommandTest::RunCommand( const CRhinoCommandContext& context )
{
  // Define the corners of the clipping plane
  CArgsRhinoGetPlane args;
  ON_3dPoint corners[4];
  CRhinoHistory history( *this );
  CRhinoCommand::result rc = RhinoGetRectangle( args, corners, &history );
  if( rc != CRhinoCommand::success )
    return rc;
 
  // Get the active view
  CRhinoView* view = RhinoApp().ActiveView();
  if( 0 == view  )
    return CRhinoCommand::failure;
 
  const ON_3dPoint& p0 = corners[0];
  const ON_3dPoint& p1 = corners[1];
  const ON_3dPoint& p2 = corners[2];
  const ON_3dPoint& p3 = corners[3];
 
  ON_Interval domain0, domain1;
  domain0.Set( 0.0, p0.DistanceTo(p1) );
  domain1.Set( 0.0, p0.DistanceTo(p3) );
 
  // Create a plane from the corner points
  ON_Plane plane( p0, p1, p3);
 
  // Create a plane surface
  ON_PlaneSurface plane_srf( plane );
  plane_srf.SetExtents( 0, domain0, true );
  plane_srf.SetExtents( 1, domain1, true );
  plane_srf.SetDomain( 0, domain0.Min(), domain0.Max() );
  plane_srf.SetDomain( 1, domain1.Min(), domain1.Max() );
 
  // Create a clipping plane object
  rc = CRhinoCommand::failure;
  CRhinoClippingPlaneObject* plane_obj = new CRhinoClippingPlaneObject();
  if( plane_obj )
  {
    plane_obj->SetPlaneSurface( plane_srf );
 
    // Add the clipping plane
    if( plane_obj->AddClipViewport(view->ActiveViewport().ViewportId()) )
    {
      context.m_doc.AddObject( plane_obj );
      context.m_doc.Regen();
      rc = CRhinoCommand::success;
    }
    else
    {
      delete plane_obj;
      plane_obj = 0;
    }
  }
 
  return rc;
}