[vtkusers] question about vtkMapper::InterpolateScalarsBeforeMappingOn

[xabi riobe]

Hi,

I have a display problem using this method. The 2 attached pictures show it,
and the code to obtain them is also attached.

In the following example I have a cube with scalars on the PointData, and i
apply a lut to its mapper.
I also ave a 2D line in the scene.
If I do not call InterpolateScalarsBeforeMappingOn on the cube's mapper, the
line is correctly red, but if I call it, then it looks like the lut is
interferring with the rendering of the line.
And if i have more 2D actors, the first one that is added to the renderer
always presents the same problem.

Can someone can explain me why is this happening? is this the correct
behaviour or is it a bug?

Thanks!



#include <limits>

#include <vtk/vtkActor.h>
#include <vtk/vtkActor2D.h>
#include <vtk/vtkCleanPolyData.h>
#include <vtk/vtkCubeSource.h>
#include <vtk/vtkDoubleArray.h>
#include <vtk/vtkLineSource.h>
#include <vtk/vtkLinearSubdivisionFilter.h>
#include <vtk/vtkLookupTable.h>
#include <vtk/vtkPointData.h>
#include <vtk/vtkPolyData.h>
#include <vtk/vtkPolyDataMapper.h>
#include <vtk/vtkPolyDataMapper2D.h>
#include <vtk/vtkProperty.h>
#include <vtk/vtkProperty2D.h>
#include <vtk/vtkRenderer.h>
#include <vtk/vtkRenderWindow.h>
#include <vtk/vtkRenderWindowInteractor.h>
#include <vtk/vtkSmartPointer.h>
#include <vtk/vtkTriangleFilter.h>

#define MY_SP(class, variable)\
   vtkSmartPointer<class> variable = vtkSmartPointer<class>::New();

//----------------------------------------------------------------------------------------------------

// implemented after the main
void RepresPositionCtrl2D(double dSize, vtkRenderer *ren);
void SetScalars(vtkMapper *Mapper);
void ConfigureMapperLut(vtkMapper *mapper);

//---------------------------------------------------------------------------------------------

int main(int , char* [])
{
   /////////////////////////////////////////////////////////
   MY_SP(vtkRenderer, ren1);
   ren1->SetBackground(0.2, 0.2, 0.2);
   MY_SP(vtkRenderWindow, renWin);
   renWin->SetSize( 1000, 896 );
   renWin->AddRenderer(ren1);
   MY_SP(vtkRenderWindowInteractor, iren);
   iren->SetRenderWindow(renWin);

   /////////////////////////////////////////////////////////
   MY_SP(vtkCubeSource, src);
   src->SetBounds(0,2,0,2,0,2);
   src->Update();

   MY_SP(vtkTriangleFilter, tri);
   tri->SetInputConnection(src->GetOutputPort());
   tri->Update();

   MY_SP(vtkCleanPolyData, clean);
   clean->SetInputConnection(tri->GetOutputPort());
   clean->Update();

   MY_SP(vtkLinearSubdivisionFilter, sub);
   sub->SetInputConnection(clean->GetOutputPort());
   sub->SetNumberOfSubdivisions(1);
   sub->Update();

   vtkPolyData *cube = sub->GetOutput();

   MY_SP(vtkPolyDataMapper, Map);
   Map->SetInput(cube);

   MY_SP(vtkActor, Act);
   Act->SetMapper(Map);
   Act->GetProperty()->SetInterpolationToFlat();

   ren1->AddActor(Act);

   /////////////////////////////////////////////////////////
   RepresPositionCtrl2D(0.2, ren1);

   SetScalars(Map);
   ConfigureMapperLut(Map);

   /////////////////////////////////////////////////////////
   ren1->ResetCamera();
   renWin->Render();
   iren->Start();

   /////////////////////////////////////////////////////////
   return 0;
}

//---------------------------------------------------------------------------------------------

void RepresPositionCtrl2D(double dSize, vtkRenderer *ren)
{
   MY_SP(vtkLineSource, m_LineH);
   m_LineH->SetPoint1(0.0, 0.0, 0.0);
   m_LineH->SetPoint2(dSize, 0.0, 0.0);

   MY_SP(vtkPolyDataMapper2D, m_MapperLH);
   m_MapperLH->SetInputConnection(m_LineH->GetOutputPort());
   m_MapperLH->ScalarVisibilityOff();

   MY_SP(vtkActor2D, m_ActorLH);
   m_ActorLH->GetProperty()->SetColor(1.0, 0.0, 0.0);
   m_ActorLH->GetProperty()->SetLineWidth(5);
   m_ActorLH->SetMapper(m_MapperLH);
   m_ActorLH->PickableOff();

   MY_SP(vtkCoordinate, pCoord);
   pCoord->SetCoordinateSystemToWorld();

   vtkSmartPointer<vtkCoordinate> coord =
vtkSmartPointer<vtkCoordinate>::New();
   coord->SetCoordinateSystemToNormalizedViewport();
   coord->SetReferenceCoordinate(pCoord);
   m_MapperLH->SetTransformCoordinate(coord);

   ren->AddActor2D(m_ActorLH);
}

void SetScalars(vtkMapper *Mapper)
{
   MY_SP(vtkDoubleArray, distArray);
   int numPts = Mapper->GetInput()->GetNumberOfPoints();
   distArray->SetNumberOfValues(numPts);

   double *scalars = distArray->WritePointer(0, numPts);
   std::fill(scalars, scalars+numPts, std::numeric_limits<double>::max());
   scalars[0] = -1.0;
   scalars[1] = -0.1;
   scalars[2] = 0.0;
   scalars[3] = 0.2;
   scalars[4] = 0.4;
   scalars[5] = 0.6;
   scalars[6] = 0.8;
   scalars[7] = 10.0;

   distArray->Modified();

   Mapper->GetInput()->GetPointData()->SetScalars(distArray);
   Mapper->GetInput()->GetPointData()->Modified();
   Mapper->Update();
}

void ConfigureMapperLut(vtkMapper *mapper)
{
   if(!mapper)
      return;

   MY_SP(vtkLookupTable, lut);
   lut->SetNumberOfColors(7);
   lut->Build();
   lut->SetTableValue(0, 0.5, 0.0, 1);
   lut->SetTableValue(1, 0, 1.0, 0);
   lut->SetTableValue(2, 1, 0, 0.5);
   lut->SetTableValue(3, 0.0, 0.5, 0.0);
   lut->SetTableValue(4, 0.0, 1, 0.5);
   lut->SetTableValue(5, 0, 0.5, 1);
   lut->SetTableValue(6, 1.0, 1.0, 1.0);
   lut->SetTableRange(-0.2, 1.0);

   mapper->ScalarVisibilityOn();
   mapper->SetLookupTable(lut);
   mapper->UseLookupTableScalarRangeOn();
   ////////////////////////////////////////////////////
   mapper->InterpolateScalarsBeforeMappingOn(); // what's wrong?
   ////////////////////////////////////////////////////
   mapper->Update();
}
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