[vtkusers] splines

[Renaud Isabelle]

Hi,
 
Thanks for your reply. But your are wrong: I set:
 
 t = ( (float)numberOfInputPoints - 1.0 ) / ( (float)numberOfOutputPoints - 1.0 ) * (float)i;
       spline_points->SetPoint(i, splineX->Evaluate(t), splineY->Evaluate(t), splineZ->Evaluate(t));

Is it not correct? Any other idea?
 
Isabelle
 
 
 
 

dean.inglis at camris.ca a écrit :

you didn't define any points:

//Generate the polyline for the spline.
spline_points = vtkPoints::New();
spline_points->SetNumberOfPoints( static_cast(numberOfOutputPoints) );

you need to also do:

spline_points->SetPoint(i,somethingX,somethingY,somethingZ);

or,

double somethingXYZ[3];
spline_points->SetPoint(i,somethingXYZ);

Dean



> 
Hi,
 
I am really confused about interpolating my glyph points with a spline. 
 
I look a lot of examples on this and I thought having understood, but actually, only my glyph are drawn. 
 
I put a TRACE instruction to see what is computed after calling spline-.Evaluate(): i got crazy values except for the first one: not so amazing that nothing is drawn! 
 
Here is what I did:
 
 
   splineX = vtkCardinalSpline::New();
   splineY = vtkCardinalSpline::New();
   splineZ = vtkCardinalSpline::New();
 
    numberOfOutputPoints = 20; //Number of points on the spline
   
 //Generate the polyline for the spline.
 spline_points = vtkPoints::New();
 spline_points->SetNumberOfPoints( static_cast<vtkIdType>(numberOfOutputPoints) );
 
 //Create the polyline.
 spline_lines = vtkCellArray::New();
 spline_lines->InsertNextCell(numberOfOutputPoints);

 for(int i=0; i<numberOfOutputPoints;i++)
  spline_lines->InsertCellPoint(i);//add points one at a time
 
 spline_polyData = vtkPolyData::New();
 spline_polyData->SetPoints(spline_points);
 spline_points->Delete();
 spline_polyData->SetLines(spline_lines);
 spline_lines->Delete();
 
 //Add thickness to the resulting line.
    tubes = vtkTubeFilter::New();
    tubes->SetInput(spline_polyData);
    tubes->SetRadius(0.075);
    tubes->SetNumberOfSides(6);
 
 vtkPolyDataMapper* spline_mapper = vtkPolyDataMapper::New();
    spline_mapper->SetInput(tubes->GetOutput());
 tubes->Delete();
 
 splines = vtkActor::New();
 splines->SetMapper(spline_mapper);
 spline_mapper->Delete();
 
 splines->GetProperty()->SetColor(1.0, 0.0, 1.0);

 

And after each click:
case vtkCommand::LeftButtonPressEvent:
     {
        vtkRenderWindowInteractor  *interactor = reinterpret_cast<vtkRenderWindowInteractor *>(caller);
       int x = interactor->GetEventPosition()[0];
       int y = interactor->GetEventPosition()[1];
 
        // Convert display point to world point
       double world_point[4];
       m_Renderer->SetDisplayPoint( x, y, 0 );
       m_Renderer->DisplayToWorld();
       m_Renderer->GetWorldPoint( world_point );
 
      // Store the point with no range checking or memory allocation.
      points->SetPoint( nodeId, world_point[0], world_point[1], world_point[2] );  
      // Create a vertex for each node. This type of cell has a single point.
      vtkIdType topology[1];
      topology[0] = nodeId; 
      vertices->InsertNextCell( 1, topology );  
 
     //create new points
     numberOfInputPoints = points->GetNumberOfPoints();
 
     if ( numberOfInputPoints >= 2 )
     {
        if(numberOfInputPoints==2) 
        {
         m_Renderer->AddActor( splines );
         splines->Delete();
        }
 
      splineX->RemoveAllPoints();
      splineY->RemoveAllPoints();
      splineZ->RemoveAllPoints();
 
      for ( int i = 0 ; i < numberOfInputPoints; i++)
     {
     //add coordinates points to the splines.
     float* point = points->GetPoint(i);
     splineX->AddPoint( i, point[0] );
     splineY->AddPoint( i, point[1] );
     splineZ->AddPoint( i, point[2] );
     }
 
     if(spline_points) spline_points->Reset();      float t = 0.0;
     for(int i=0; i<numberOfOutputPoints;i++)
     {
        t = ( (float)numberOfInputPoints - 1.0 ) / ( (float)numberOfOutputPoints - 1.0 ) * (float)i;
       spline_points->SetPoint(i, splineX->Evaluate(t), splineY->Evaluate(t), splineZ->Evaluate(t));
  
       float* pt = spline_points->GetPoint(i);
      TRACE("spline points:%f %f %f\n", pt[0], pt[1], pt[2]);
  }
  
    spline_polyData->Modified();
}
   
   nodeId++;   
   m_glyphActor->VisibilityOn();   
   splines->VisibilityOn();   
   this->Render();
  }    
  break;  




- Does someone see what is wrong? Insofar as my glyph are correcly drawn, I assume that my input points are correct. So what's wrong? 
 
Please help me,
 
Isabelle


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