[vtkusers] How to get pixel color from 3D coordinates ?

[corentin.desfarges]

Hi 

I'm trying to get the color of a pixel picked from a vtkPolyData. 
I tried to combine this two tutorials : PickPixel and (Point)Picking

I can get the coordinates of the picked point, but unfortunatly, I'm can't
get the vtkCell... 

Here is the code I use : 

    std::string inputFilename = "/home/cde/data/mesh.vtk"; 
    vtkSmartPointer<vtkGenericDataObjectReader> reader =
vtkSmartPointer<vtkGenericDataObjectReader>::New(); 
    reader->SetFileName(inputFilename.c_str()); 
    reader->Update(); 
    polydata = reader->GetPolyDataOutput(); 

    [...] 

    double* pos = picker->GetPickPosition(); 

    vtkPointData* pd = polydata->GetPointData(); 
    if( !pd ) 
    { 
        return; 
    } 

    // Use tolerance as a function of size of source data 
    double tol2 = polydata->GetLength(); 
    tol2 = tol2 ? tol2*tol2 / 1000.0 : 0.001; 

    // Find the cell that contains pos 
    int subId; 
    double pcoords[3], weights[8]; 
    vtkCell* cell = polydata->FindAndGetCell( pos, NULL, -1, tol2, subId,
pcoords, weights ); 

    if( cell ) 
    { 
        // Interpolate the point data 
        this->PointData->InterpolatePoint( pd, 0, cell->PointIds, weights ); 
        double* tuple = this->PointData->GetScalars()->GetTuple( 0 ); 

        double r = std::stod(vtkVariant(tuple[0]).ToString())/255; 
        double g = std::stod(vtkVariant(tuple[1]).ToString())/255; 
        double b = std::stod(vtkVariant(tuple[2]).ToString())/255; 

        std::cout << r*255 << " " << g*255 << " " << b*255 << std::endl; 

        renderer->SetBackground(r,g,b); 
    } 
    else 
    { 
        std::cout << "no cell found " << std::endl; 
    } 

Thanks for your help, 

Corentin



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