[vtkusers] A Problem About vtkXYPlotActor

[LiuNiansheng]

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.
thanks.
sincerely yours:Elo

 		 	   		  
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