[vtkusers] Mark specific points on a poldata object

[Wenlong Wang]

Hi, David,

Thank you for your reply.

Yes, the code clip I attached is building a polydata object for the
landmarks only and there is another polydata object for the surface.

What I want to make is the landmarks are drawn on the screen while another
surface is show. However, when the application runs, only the surface is
shown, the landmarks are never appreared. I tried to change the z-coordinate
by hand, but they still don't appear.

Could it be anything wrong with the visualization pipeline? I think I've
accomplish the basic operation to visualize actors in the code clip.

Thank you for your kind help。

Wenlong

2011/10/11 David E DeMarle <dave.demarle at kitware.com>

> You have to have as many tuples in the scalars array as there are
> points in the polydata. You have only as many tuples as there are
> landmark points.
>
> Alternatively might make another polydata that contains only the
> landmark points and draw both polydata. Scale the landmark polydata up
> slightly to avoid z-tearing.
>
> David E DeMarle
> Kitware, Inc.
> R&D Engineer
> 21 Corporate Drive
> Clifton Park, NY 12065-8662
> Phone: 518-881-4909
>
>
>
> On Tue, Oct 11, 2011 at 9:17 AM, Wenlong Wang <scc.wwl at gmail.com> wrote:
> > Dear all,
> >
> > Is there anyone know how to change the color of points with specific
> point
> > ID?
> >
> > I do it like this, but the surface appeared but none of these point is
> > shown.
> >
> > Here is the code,
> >
> >     vtkPoints* newpoints = vtkPoints::New();
> >     for (int i = 0; i < sizeof(landmarks)/sizeof(double); i++)
> >     {
> >         double temp_point[3];
> >         points->GetPoint(vtkIdType(landmarks[i]), temp_point);
> >         newpoints->InsertPoint(vtkIdType(i), temp_point[0],
> temp_point[1],
> > temp_point[2]);
> >     }
> >
> >     vtkPolyData* newpolydata = vtkPolyData::New();
> >     newpolydata->SetPoints(newpoints);
> >
> >     vtkFloatArray* newarray = vtkFloatArray::New();
> >     for (int i = 0; i < sizeof(landmarks)/sizeof(double); i++)
> >     {
> >         newarray->InsertTuple1(vtkIdType(i), double(i));
> >     }
> >
> >     newpolydata->GetPointData()->SetScalars(newarray);
> >
> >     vtkPolyDataMapper* newmapper = vtkPolyDataMapper::New();
> >     newmapper->SetInput(newpolydata);
> >     newmapper->SetScalarRange(0, 7);
> >     newmapper->SetScalarVisibility(0);
> >
> >     vtkActor* newactor = vtkActor::New();
> >     newactor->SetMapper(newmapper);
> >     newactor->GetProperty()->SetColor(0.0, 1.0, 0.0);
> >     newactor->GetProperty()->SetPointSize(3);
> >
> >     ren->AddActor(newactor);
> >     renWin->AddRenderer(ren);
> >
> >     ren->Render();
> >     renWin->Render();
> >
> > where 'ren' is a vtkRenderer object, ‘renWin’ is a vtkRenderWindow
> object,
> > and 'landmarks' is an array stores vtk point IDs.
> >
> > Can anybody help me with this? I'll be very grateful.
> >
> > Thank you all so much.
> >
> > Bests
> > Wenlong
> >
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