[vtkusers] A Problem About vtkXYPlotActor

[Adriano Gagliardi]

Hi Elo,
 
So, you have set your y-axis range to be between 0 and 8, you then plot a curve where some of those y-values are out of this range, so it doesn't plot them (it clips them out). This appears to be normal behaviour in my opinion. If you want to see all your curves, then you'll have to rescale your y-axis to fit them in by setting the y-axis range from 0 to 15. Were you assuming it would automatically fit the axes to the data, as within ParaView? This option may still be there, but I've never used it.
 
Cheers,
 
Adriano
 

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Adriano Gagliardi MEng PhD
Business Sector Leader
Computational Aerodynamics
Aircraft Research Association Ltd.
Manton Lane
Bedford

Tel: 01234 32 4644
E-mail: agagliardi at ara.co.uk
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From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On Behalf Of LiuNiansheng
Sent: 09 July 2010 03:56
To: VTK
Subject: [vtkusers] A Problem About vtkXYPlotActor


Hi everyone: 

I'm a user of vtk. When I use vtkXYPlotActor to draw some lines at a XYPlot, I found vtk miss one line.
That's my sample code of vtkXYPlotActor:
========================================================================= #include "vtkFloatArray.h" #include "vtkFieldData.h" #include "vtkDataObject.h" #include "vtkXYPlotActor.h" #include "vtkXYPlotWidget.h" #include "vtkMath.h" #include "vtkRenderWindow.h" #include "vtkRenderer.h" #include "vtkRenderWindowInteractor.h" int main() { vtkFloatArray* vtkXYValues = vtkFloatArray::New(); vtkXYValues->SetNumberOfComponents( static_cast<vtkIdType>(2) ); float xy[2]; xy[0] = static_cast<float>(0); xy[1] = static_cast<float>(0) ; vtkXYValues->InsertNextTuple( xy ); xy[0] = static_cast<float>(2); xy[1] = static_cast<float>(3) ; vtkXYValues->InsertNextTuple( xy ); xy[0] = static_cast<float>(4); xy[1] = static_cast<float>(15) ; vtkXYValues->InsertNextTuple( xy ); xy[0] = static_cast<float>(6); xy[1] = static_cast<float>(1) ; vtkXYValues->InsertNextTuple( xy ); xy[0] = static_cast<float>(7); xy[1] = static_cast<float>(0.1) ; vtkXYValues->InsertNextTuple( xy ); xy[0] = static_cast<float>(8); xy[1] = static_cast<float>(10) ; vtkXYValues->InsertNextTuple( xy ); xy[0] = static_cast<float>(9); xy[1] = static_cast<float>(9) ; vtkXYValues->InsertNextTuple( xy ); xy[0] = static_cast<float>(10); xy[1] = static_cast<float>(0) ; vtkXYValues->InsertNextTuple( xy ); vtkFieldData* vtkGraphFieldData = vtkFieldData::New(); vtkGraphFieldData->AddArray( vtkXYValues ); vtkXYValues->Delete(); vtkDataObject* vtkGraphDataObject = vtkDataObject::New(); vtkGraphDataObject->SetFieldData( vtkGraphFieldData ); vtkGraphFieldData->Delete(); vtkXYPlotActor* vtkGraph = vtkXYPlotActor::New(); vtkGraph->AddDataObjectInput( vtkGraphDataObject ); vtkGraphDataObject->Delete(); vtkGraph->SetDataObjectPlotModeToColumns(); vtkGraph->SetXValuesToValue(); int curve = 0; vtkGraph->SetDataObjectXComponent( curve, 0 ); vtkGraph->SetDataObjectYComponent( curve, 1 ); vtkGraph->SetXRange( 0, 10); vtkGraph->SetYRange( 0, 8); vtkGraph->SetPlotColor( curve, 1,0,0 ); vtkRenderer* renderer = vtkRenderer::New(); renderer->AddActor2D( vtkGraph ); vtkRenderWindow* renderWin = vtkRenderWindow::New(); renderWin->AddRenderer( renderer ); vtkRenderWindowInteractor* interactor =vtkRenderWindowInteractor::New(); interactor->SetRenderWindow( renderWin ); vtkXYPlotWidget* vtkXYPlotWidget = vtkXYPlotWidget::New(); vtkXYPlotWidget->SetXYPlotActor( vtkGraph ); vtkXYPlotWidget->SetInteractor( interactor ); vtkXYPlotWidget->SetEnabled( true ); interactor->Initialize(); interactor->Start(); return 0; } ========================================================================= I define eight points,a(0,0), b(2,3), c(4,15), d(6,1), e(7,0), f(8,10), g(9,9),h(10,0). And the range of xy axis is defined from point (0,0) 
to (10,8). So there are three points(cfg) out of range. There should be six lines except the line fg which is out of range, but only five lines 
have been drawn. when I change these point to test, I found the line which the value of y axis is from 0(the min value of y axis) 
to a value bigger than the max value of y axis will be ignored by vtk. 


 I guess the problem maybe happen when clipping data. So I debugged vtkXYPlotActor source, and I found the function  
named ClipPlotData() have been called in the function CreatPlotData(). 
The algorithm of clipping data is no problem. the number of lines which should be drawn is six.


Cause I don't have enough time to do further research. If anyone has any information about this problem, please let me know.


th anks.


sincerely yours:
Elo




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