[vtkusers] double vtkDataArray::GetTuple1(vtkIdType i) vs void vtkDataArray::GetTuple(vtkIdType i, double *tuple)

[Maarten Beek]

Hi all,

I experienced a crash in my algorithm derived from vtkThreadedImageAlgorithm, that (I think) I solved, but that I don't understand. Is there some one who can shed some light on the following?

What I am trying to do is adding a flag identifying the input(s) that contribute to the value of each pixel in the output image


//----------------------------------------------------------------------------
// This templated function executes the filter for any type of data.
template <class OT>
void cmvtkTemplatedExecute(cmvtkDRRGenerator2* self,
                               vtkDataSetCollection* inputs, vtkImageData* output,
                               int extent[6], int threadId, OT*)
{
   
 vtkUnsignedCharArray* uchararray = 
vtkUnsignedCharArray::SafeDownCast(output->GetPointData()->GetScalars("input_flag"));

    int numinputs = inputs->GetNumberOfItems();
    for( int input_i = 0; input_i < numinputs; ++input_i )
    {
        vtkImageData* input = vtkImageData::SafeDownCast(inputs->GetItem(input_i));
        if( 0 == input )
        {
            // should not happen
            continue;
        }
        const int* dims= output->GetDimensions();

        vtkImageProgressIterator<OT> outIt(output, extent, self, threadId);
        vtkIdType voxelid = extent[0] + size[0]*extent[2] + size[0]*size[1]*extent[4];
    
        // Loop through output pixels
        while( !outIt.IsAtEnd() )
        {
            OT* outSI = outIt.BeginSpan();
            OT* outSIEnd = outIt.EndSpan();

            while( outSI != outSIEnd )
            {
                // start with setting pixel to 0.0
                if( input_i == 0 )
                {
                    *outSI = 0.0;
                }


                OT result = 0.0;

                //.... some math resulting in a value for result....

                *outSI += result;

                // this input image participates in voxel values; adjust bit
                if( 0.0 < result && 0 != uchararray )
                {
                    // The commented code crashes...

                    //unsigned char oldvalue = uchararray->GetTuple1(voxelid);
                    //unsigned char newvalue = oldvalue | (1<<input_i);
                    //uchararray->SetTuple1(voxelid, newvalue);

                    double dOldValue;
                    uchararray->GetTuple(voxelid, &dOldValue);
                    unsigned char chOldValue = static_cast<unsigned char>(dOldValue);
                    unsigned char chNewValue = chOldValue | (1<<input_i);
                    double dNewValue = static_cast<double>(chNewValue);
                    uchararray->SetTuple(voxelid, &dNewValue);
                }

                ++outSI;
                ++voxelid;
            }
            outIt.NextSpan();
        }
    } // input_i < numinputs
}
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