[vtkusers] Displaying a poly line using an existing array of doubles

[Anton Deguet]

Hello,

I have been able to display a polyline using an existing array of doubles along with a set of point IDs.   I am now trying to do the following:
- change the data (direct access to the array of doubles)
- refresh the point IDs (the array is a circular buffer)
At that point, I can't seem to get VTK to refresh the poly line.

My test code looks like this for setup:

	// use vctDynamicVector of 3D points (vct3) 
	actualData.SetSize(10);
	actualData[0] = vct3(1.0, 0.0, 0.0);
	actualData[1] = vct3(1.0, 2.0, 0.0);
	actualData[2] = vct3(4.0, 1.0, 0.0);
	actualData[3] = vct3(1.0, 0.0, 2.0);
	actualData[4] = vct3(3.0, 1.0, 2.0);
	actualData[5] = vct3(0.0, 0.0, 0.0);
	actualData[6] = vct3(1.0, 0.0, 0.0);
	actualData[7] = vct3(0.0, 1.0, 0.0);
	actualData[8] = vct3(0.0, 1.0, 2.0);
	actualData[9] = vct3(1.0, 2.0, 3.0);

	// create a VTK array that points to the cisst vector data
	dataArray = vtkDoubleArray::New();
	dataArray->SetNumberOfComponents(vct3::SIZE); // we set the number of components 
	dataArray->SetArray(actualData[0].Pointer(), actualData.size(), 1); // number of points, last parameter tells VTK to not free the memory

	// points use this data
	points = vtkPoints::New();
	points->SetData(dataArray);

	// polyline is mostly a list of indices
	polyLine = vtkPolyLine::New();
	polyLine->GetPointIds()->SetNumberOfIds(5);
	for (unsigned int i = 0; i < 5; i++) {
		polyLine->GetPointIds()->SetId(i, 5 + i);
	}
 
 	// Create a cell array to store the lines in and add the lines to it
	cells = vtkCellArray::New();
	cells->InsertNextCell(polyLine);
 
	// Create a polydata to store everything in
	polyData = vtkPolyData::New();
	polyData->SetPoints(points);
	polyData->SetLines(cells);
 
	// setup actor and mapper
	mapper = vtkPolyDataMapper::New();
	mapper->SetInput(polyData);
  
	actor = vtkActor::New();
	actor->SetMapper(mapper);

The initial render works fine.   Then in refresh (in a loop), I tried:

	// refresh which points to use
	Counter++;
	if (Counter > 5) {
		Counter = 0;
	}
	for (unsigned int i = 0; i < 5; i++) {
		polyLine->GetPointIds()->SetId(i, Counter + i);
	}

	// all following are attempts to tell VTK to refresh
	dataArray->SetArray(actualData[0].Pointer(), actualData.size(), 1);
	points->Modified();
	dataArray->Modified();
	polyData->Modified();
	polyLine->Modified();
	cells->Modified();
	mapper->Modified();

FYI, Initially my refresh happened in a different thread but it now happens in the same thread that creates all the VTK objects.   What is the obvious thing I am missing?

Anton

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Anton Deguet, Research Engineer, ERC-CISST/LCSR, Johns Hopkins University