[vtkusers] Drawing a simple line graph

[beth at portugalmail.pt]

Hi John,

I'll try this, and see how it works.

Thanks for you great help!

Best regards,

Beth

Citando John Platt <jcplatt at dsl.pipex.com>:

 Hi,
 
 I would use vtkXYPlotActor as a template for your other types of plot.
 Use viewport coordinates for your axes and your points (the default for
 vtkPolyDataMapper2D). Create the point values after the plot area and
 axes have been positioned. Normalise your plot data then scale it by the
 length of each axis (pos2-pos) which will be pixels for viewport
 coordinates.
 
 Try modifying vtkXYPlotActor::CreatePlotData() for your custom plots.
 
 Anyway, here is your original code with some changes.
 
    // Some points to plot.
    vtkPoints* polyLinePoints = vtkPoints::New();
    polyLinePoints->InsertNextPoint( 0, 0, 0 );
    polyLinePoints->InsertNextPoint(  50, 20, 0 );
    polyLinePoints->InsertNextPoint( 100, 60, 0 );
    polyLinePoints->InsertNextPoint( 160, 50, 0 );
    polyLinePoints->InsertNextPoint( 200, 100, 0 );
 
    double* bounds = polyLinePoints->GetBounds();
    double xRange[2]; xRange[0]=bounds[0]; xRange[1]=bounds[1]; 
    double yRange[2]; yRange[0]=bounds[2]; yRange[1]=bounds[3]; 
 
    // All the lines joining the plot points.
    vtkCellArray* lines = vtkCellArray::New();
    for ( int i = 0; i < polyLinePoints->GetNumberOfPoints() - 1; ++i )
    {
       vtkIdType topol[2];
       topol[0] = i;
       topol[1] = i+1;
       lines->InsertNextCell( 2, topol );
    }
 
    // Create polydata from points & lines.
    vtkPolyData* polydata = vtkPolyData::New();
    polydata->SetPoints(polyLinePoints);
    polydata->SetLines(lines);
    polydata->BuildCells();
 
    // Map it to 2D.
    vtkPolyDataMapper2D* mapper = vtkPolyDataMapper2D::New();
    mapper->SetInput(polydata);
    vtkActor2D* actor = vtkActor2D::New();
    actor->SetMapper(mapper);
 
    // The default coordinate systems for positioning 2D actors are
 VIEWPORT
    // coordinates for SetPosition() and NORMALISED VIEWPORT relative to
 Position
    // for SetPosition2(). Change SetPosition() to use NORMALISED
 VIEWPORT.
 
  
 actor->GetPositionCoordinate()->SetCoordinateSystemToNormalizedViewport(
 );
    actor->GetPositionCoordinate()->SetValue(0.2, 0.2);
    actor->GetPosition2Coordinate()->SetValue(0.6, 0.7);
    actor->GetProperty()->SetColor(1, 0, 0);
 
    // Define axes
    vtkAxisActor2D *axesX = vtkAxisActor2D::New();
    axesX->GetPositionCoordinate()->SetCoordinateSystemToViewport();
    axesX->GetPosition2Coordinate()->SetCoordinateSystemToViewport();
    axesX->SetLabelFormat("%g");
    axesX->SetRange( xRange );
    axesX->SetTitle("Time (s)");
 
    vtkAxisActor2D *axesY = vtkAxisActor2D::New();
    axesY->GetPositionCoordinate()->SetCoordinateSystemToViewport();
    axesY->GetPosition2Coordinate()->SetCoordinateSystemToViewport();
    axesY->SetLabelFormat("%g");
    axesY->SetRange( yRange[1], yRange[0] ); // note reversal
 
    // Add plot actor and axes actors to renderer.
    vtkRenderer* ren = vtkRenderer::New(); 
    ren->AddActor2D(actor);
    ren->AddViewProp(axesX);
    ren->AddViewProp(axesY);
 
    vtkRenderWindow* renWin = vtkRenderWindow::New();    
    renWin->AddRenderer(ren);
    renWin->SetSize( 801, 601 );
 
    vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
    iren->SetRenderWindow(renWin);
    iren->Initialize(); // need a window size to determine viewport
 coordinates
 
    // Position axes using the plot actor viewport coordinates.
    int* p  =
 actor->GetPositionCoordinate()->GetComputedViewportValue(ren);
    double pos[2]; pos[0]=(double)p[0]; pos[1]=(double)p[1];
    int* p2 =
 actor->GetPosition2Coordinate()->GetComputedViewportValue(ren);
    double pos2[2]; pos2[0]=(double)p2[0]; pos2[1]=(double)p2[1]; 
 
    axesX->GetPositionCoordinate()->SetValue( pos  );
    axesX->GetPosition2Coordinate()->SetValue( pos2[0], pos[1]  );
    axesY->GetPositionCoordinate()->SetValue(  pos[0],  pos2[1] ); //
 left, top
    axesY->GetPosition2Coordinate()->SetValue( pos  );             //
 left, bottom
 
    // Convert plot data to VIEWPORT coordinates (pixel centres relative
 to the
    // Position() coordinate of the plot actor).
 
    for ( i = 0; i < polyLinePoints->GetNumberOfPoints(); ++i )
    {
       double* xyz = polyLinePoints->GetPoint( i );
       xyz[0] =
 (xyz[0]-xRange[0])/(xRange[1]-xRange[0])*(pos2[0]-pos[0]);
       xyz[1] =
 (xyz[1]-yRange[0])/(yRange[1]-yRange[0])*(pos2[1]-pos[1]);
       xyz[2] = 0.0;
       polyLinePoints->SetPoint( i, xyz  );
    }
 
    renWin->Render();
    iren->Start();
 
    return 0;
 
 HTH
 
 John.
 
 -----Original Message-----
 From: beth at portugalmail.pt [mailto:beth at portugalmail.pt] 
 Sent: 17 November 2006 19:30
 To: John Platt
 Cc: vtkusers at vtk.org
 Subject: RE: [vtkusers] Drawing a simple line graph 
 
 Hi,
 
 I used non-normalized values, such as time (in seconds) and heartbeat 
 frequency (between 70 up to 160). These values are captured by sensors,
 and 
 are  integers (70-160) and floats (0.000-78.675). They define x (time)
 and y 
 (heartbeat) values.
 
 I thought that they would be properly converted by the mapper...
 
 By the way, I used vtkXYPlotActor and it worked perfectly. However, I
 would 
 still want to know what is wrong here, because I want to create other
 types of 
 graphs (bar, histograms, area, etc.).
 
 Thanks and best regards,
 
 Elizabeth
 
 Citando John Platt <jcplatt at dsl.pipex.com>:
 
  Hi,
  
  By default, vtkPolyDataMapper2D, transforms 3D data into 2D data by
  ignoring the z-coordinate of the 3D points in vtkPolyData, and taking
  the (x,y) values as VIEWPORT values (pixel centers relative to the
  lower-left corner of the viewport in the render window).
  
  What values have you used in 'polyLinePoints'.
  
  John.
  
  -----Original Message-----
  From: vtkusers-bounces+jcplatt=dsl.pipex.com at vtk.org
  [mailto:vtkusers-bounces+jcplatt=dsl.pipex.com at vtk.org] On Behalf Of
  beth at portugalmail.pt
  Sent: 17 November 2006 13:33
  To: John Platt
  Cc: vtkusers at vtk.org
  Subject: RE: [vtkusers] Drawing a simple line graph 
  
  Hi,
  
  Yes, I know that Position2 is relative to Position. But evend adjusting
  other 
  values, it does not work.
  No, I can try to use vtkXYPlotActor, however I do want also to create
 an
  area 
  graph (using a polygon instead a polyline), and for that, I'll have to
  know 
  how to work properly with this situation...
  
  Any other tip?
  
  Thanks and best regards,
  
  Elizabeth
  
  
  Citando John Platt <jcplatt at dsl.pipex.com>:
  
   Hi,
   
   I seem to recall that the Position2 coordinate is relative to
 Position.
   
   Is there any reason you cannot use vtkXYPlotActor?
   
   John.
   
   -----Original Message-----
   From: vtkusers-bounces+jcplatt=dsl.pipex.com at vtk.org
   [mailto:vtkusers-bounces+jcplatt=dsl.pipex.com at vtk.org] On Behalf Of
   beth at portugalmail.pt
   Sent: 16 November 2006 20:53
   To: vtkusers at vtk.org
   Subject: [vtkusers] Drawing a simple line graph 
   
   Hi,
    
   I'm trying to create a simple line graph. For that, I created a
  polyline
   and 2 
   axis.My piece of code looks like this:
    
   // Create a polyline
    vtkPolyData* polydata = vtkPolyData::New();
    polydata->SetPoints(polyLinePoints);
    polydata->SetLines(line);
    
   // Maps it to 2D
    vtkPolyDataMapper2D *mapper = vtkPolyDataMapper2D::New();
    mapper->SetInput(polydata);
    
   // Creates an actor, defining its limits according the graph area
   defined by 
   the axes below
    vtkActor2D *actor = vtkActor2D::New();
    actor->SetMapper(mapper);
    
   
  
 actor->GetPositionCoordinate()->SetCoordinateSystemToNormalizedViewport(
   );
    actor->GetPositionCoordinate()->SetValue(0.05, 0.2);
    
   
  
 actor->GetPosition2Coordinate()->SetCoordinateSystemToNormalizedViewport
   (); // it's not working properly!!!
    actor->GetPosition2Coordinate()->SetValue(0.90, 0.9); // it's not
   working 
   properly!!!
    actor->GetProperty()->SetColor(1, 0, 0);
   
   // Define axes
    vtkCoordinate *coords_x1 = vtkCoordinate::New();
    coords_x1->SetValue(0.05, 0.2);
    
    vtkCoordinate *coords_x2 = vtkCoordinate::New();
    coords_x2->SetValue(0.95, 0.2);
    
    vtkCoordinate *coords_y1 = vtkCoordinate::New();
    coords_y1->SetValue(0.05, 0.2);
    
    vtkCoordinate *coords_y2 = vtkCoordinate::New();
    coords_y2->SetValue(0.05, 0.95);
    
    vtkAxisActor2D *axesX = vtkAxisActor2D::New();
    axesX->SetPoint1(coords_x1->GetValue());
    axesX->SetPoint2(coords_x2->GetValue());
    axesX->SetLabelFormat("%3.2f");
    axesX->SetFontFactor(1.2);
    axesX->SetRange(0, t); // t is the maximum x value in the polyline
   points
    axesX->SetTitle("Time (s)");
    axesX->SetNumberOfLabels(10);
    axesX->AdjustLabelsOn();
    axesX->LabelVisibilityOn();
    axesX->TickVisibilityOn();
    
    vtkAxisActor2D *axesY = vtkAxisActor2D::New();
    axesY->SetPoint1(coords_y1->GetValue());
    axesY->SetPoint2(coords_y2->GetValue());
    axesY->SetLabelFormat("%3.2f");
    axesY->SetFontFactor(1);
    axesY->SetRange(0, sCardMax); // Máximum y value in polyline points
    axesY->AdjustLabelsOn();
    axesY->LabelVisibilityOn();
    axesY->TickVisibilityOn();
    
   .....the usual stuff....creates the renderer...
    
   rw->AddActor2D(actor);
   rw->AddViewProp(axesX);
   rw->AddViewProp(axesY);
    
    
   Well, the line graph is drawn, but the problem is that axes values and
   line 
   values are not matching. 
   It seems that the GetPosition2Coordinate is not working at all,
 because
   the 
   mapping of the line to the graph effective area (that is defined by
 the
   limits 
   of the axes - xmin, ymin and xmax, ymax) is not being done. It just
  puts
   the 
   polyline at the initial position defined by GetPositionCoordinate, and
   draws 
   it as the output given by the vtkPolyDataMapper2D.
    
   What should I do?
    
   Thanks for any help!
    
   Regards,
    
   Elizabeth
   
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