switch to using a filter and storing angles in the vtk data object

src/main.cc

@@ -1,5 +1,7 @@
-#include "vtkCell.h"
-#include "vtkUnstructuredGrid.h"
+#include <vtkCell.h>
+#include <vtkPointData.h>
+#include <vtkCellData.h>
+#include <vtkUnstructuredGrid.h>
 #include <algorithm>
 #include <vtkActor.h>
 #include <vtkCamera.h>
@@ -20,33 +22,14 @@
 #include <vtkXMLPolyDataReader.h>
 #include <vtkPiecewiseFunction.h>
 #include <vtkCellIterator.h>
+#include <vtkUnstructuredGridAlgorithm.h>
+#include <vtkDoubleArray.h>
 
 #include <array>
 #include <vector>
 #include <algorithm>
 
 
-template <typename T>
-T average(const std::vector<T> &data) {
-	T avg = 0;
-	for (const T &t : data) {
-		avg += t;
-	}
-	return avg / data.size();
-}
-
-
-template <typename T>
-T standard_deviation(const std::vector<T> &data) {
-	T avg = average(data);
-	T stddev = 0;
-	for (const T &t : data) {
-		stddev += (t - avg) * (t - avg);
-	}
-	return std::sqrt(stddev / data.size());
-}
-
-
 void cellAngles(vtkDataSet *dataSet, vtkIdList *idList, double *angles) {
 	// std::cout << "nb points: " << idList->GetNumberOfIds() << std::endl;
 	double a[3], b[3], c[3], d[3];
@@ -94,6 +77,66 @@ void cellAngles(vtkDataSet *dataSet, vtkIdList *idList, double *angles) {
 }
 
 
+class AddAngleComputationAlgorithm : public vtkUnstructuredGridAlgorithm {
+public:
+	static AddAngleComputationAlgorithm *New();
+	vtkTypeMacro(AddAngleComputationAlgorithm, vtkUnstructuredGridAlgorithm);
+
+	vtkTypeBool RequestData(vtkInformation *request,
+							vtkInformationVector **inputVector,
+							vtkInformationVector *outputVector) override {
+		(void) request;
+		vtkUnstructuredGrid* input =
+			vtkUnstructuredGrid::GetData(inputVector[0]);
+		vtkUnstructuredGrid* output =
+			vtkUnstructuredGrid::GetData(outputVector);
+		output->CopyStructure(input);
+		output->GetPointData()->PassData(input->GetPointData());
+		vtkCellData *cellData = output->GetCellData();
+		cellData->PassData(input->GetCellData());
+		vtkNew<vtkDoubleArray> anglesArray;
+		anglesArray->SetName("angles");
+		anglesArray->SetNumberOfComponents(12);
+		anglesArray->SetNumberOfTuples(input->GetNumberOfCells());
+		double *anglesBase = anglesArray->GetPointer(0);
+		size_t i = 0;
+		auto it = input->NewCellIterator();
+		for (it->InitTraversal(); !it->IsDoneWithTraversal(); it->GoToNextCell()) {
+			if (it->GetCellType() != VTK_TETRA) continue;
+			cellAngles(input, it->GetPointIds(), anglesBase + i);
+			i += 12;
+		}
+		cellData->AddArray((vtkAbstractArray *) anglesArray);
+		return true;
+	}
+
+protected:
+	~AddAngleComputationAlgorithm() override = default;
+};
+
+vtkStandardNewMacro(AddAngleComputationAlgorithm);
+
+template <typename T>
+T average(const std::vector<T> &data) {
+	T avg = 0;
+	for (const T &t : data) {
+		avg += t;
+	}
+	return avg / data.size();
+}
+
+
+template <typename T>
+T standard_deviation(const std::vector<T> &data) {
+	T avg = average(data);
+	T stddev = 0;
+	for (const T &t : data) {
+		stddev += (t - avg) * (t - avg);
+	}
+	return std::sqrt(stddev / data.size());
+}
+
+
 int main(int argc, char **argv) {
 	if (argc != 2) {
 		std::cerr << "Usage: " << argv[0] << " FILE.vtk" << std::endl;
@@ -108,28 +151,26 @@ int main(int argc, char **argv) {
 	// vtkNew<vtkXMLPolyDataReader> reader;
 	vtkNew<vtkUnstructuredGridReader> reader;
 	reader->SetFileName(argv[1]);
-	reader->Update();
-	vtkUnstructuredGrid *grid = reader->GetOutput();
-	auto it = grid->NewCellIterator();
-	std::vector<double> angles(grid->GetNumberOfCells() * 12);
-	size_t i = 0;
-	for (it->InitTraversal(); !it->IsDoneWithTraversal(); it->GoToNextCell()) {
-		if (it->GetCellType() != VTK_TETRA) continue;
-		// double angles[12];
-		cellAngles(grid, it->GetPointIds(), angles.data() + i);
-		i += 12;
-		// for (size_t i = 0; i < 12; i++) {
-		// 	std::cout << angles[i] << ", ";
-		// }
-		// std::cout << "\b\b \n";
+	// reader->Update();
+	vtkNew<AddAngleComputationAlgorithm> addAngles;
+	addAngles->SetInputConnection(reader->GetOutputPort());
+	addAngles->Update();
+	vtkUnstructuredGrid *grid = addAngles->GetOutput();
+	auto *angles = vtkDoubleArray::SafeDownCast(grid->GetCellData()->GetArray("angles"));
+	for (ssize_t i = 0; i < angles->GetNumberOfTuples(); i++) {
+		std::cout << "cell " << i << ": ";
+		for (ssize_t j = 0; j < angles->GetNumberOfComponents(); j++) {
+			std::cout << angles->GetTuple(i)[j] << ", ";
 		}
-	std::cout << "avg: " << average(angles)
-			  << ", stddev: " << standard_deviation(angles)
-			  << ", min: " << *std::min_element(angles.begin(), angles.end())
-			  << ", max: " << *std::max_element(angles.begin(), angles.end()) << std::endl;
+		std::cout << "\b\b \n";
+	}
+	// std::cout << "avg: " << average(angles)
+	// 		  << ", stddev: " << standard_deviation(angles)
+	// 		  << ", min: " << *std::min_element(angles.begin(), angles.end())
+	// 		  << ", max: " << *std::max_element(angles.begin(), angles.end()) << std::endl;
 
 	vtkNew<vtkOpenGLProjectedTetrahedraMapper> volumeMapper;
-	volumeMapper->SetInputConnection(reader->GetOutputPort());
+	volumeMapper->SetInputConnection(addAngles->GetOutputPort());
 	// vtkNew<vtkPolyDataMapper> mapper;
 	// mapper->SetInputConnection(reader->GetOutputPort());