I’m trying to use the GradentFilter example:
https://vtk.org/Wiki/VTK/Examples/Cxx/PolyData/GradientFilter
I can’t get my mesh to show the color changes the way the one in the picture shows. Is there some example data I can look at? I’d like to colorize my gradients.
Here is what I’m doing:
#include <string>
#include <vtkSmartPointer.h>
#include <vtkMarchingCubes.h>
#include <vtkVoxelModeller.h>
#include <vtkSphereSource.h>
#include <vtkImageData.h>
#include <vtkDICOMImageReader.h>
#include <vtkJPEGReader.h>
#include <vtkActor.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkImageViewer2.h>
#include <vtkSmartPointer.h>
#include <vtkActor.h>
#include <vtkArrowSource.h>
#include <vtkAssignAttribute.h>
#include <vtkCamera.h>
#include <vtkExtractEdges.h>
#include <vtkGlyph3D.h>
#include <vtkGradientFilter.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkTubeFilter.h>
#include <vtkUnstructuredGridReader.h>
using namespace std;
int main(int argc, char *argv[])
{
vtkSmartPointer<vtkImageData> volume =
vtkSmartPointer<vtkImageData>::New();
double isoValue;
vtkSmartPointer<vtkDICOMImageReader> reader = vtkSmartPointer<vtkDICOMImageReader>::New();
reader->SetDirectoryName(argv[1]);
reader->Update();
volume->DeepCopy(reader->GetOutput());
isoValue = atof(argv[2]);
std::string inputFilename = argv[1];
vtkSmartPointer<vtkMarchingCubes> surface =
vtkSmartPointer<vtkMarchingCubes>::New();
surface->SetInputData(volume);
surface->ComputeNormalsOn();
surface->SetValue(0, isoValue);
// Create polydata from iso-surface
vtkSmartPointer<vtkPolyData> marched = vtkSmartPointer<vtkPolyData>::New();
surface->Update();
marched->DeepCopy(surface->GetOutput());
std::cout << "Number of points: " << marched->GetNumberOfPoints() << std::endl;
vtkSmartPointer<vtkExtractEdges> edges = vtkSmartPointer<vtkExtractEdges>::New();
edges->SetInputData(marched); // ->SetInputData(outputMesh); // ->SetInputConnection(reader->GetOutputPort());
vtkSmartPointer<vtkTubeFilter> tubes = vtkSmartPointer<vtkTubeFilter>::New();
tubes->SetInputConnection(edges->GetOutputPort());
tubes->SetRadius(0.01);
tubes->SetVaryRadiusToVaryRadiusOff();
tubes->SetNumberOfSides(4);
vtkSmartPointer<vtkPolyDataMapper> tubesMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
tubesMapper->SetInputConnection(tubes->GetOutputPort());
tubesMapper->SetScalarRange(0.0, 25.0);
vtkSmartPointer<vtkActor> tubesActor = vtkSmartPointer<vtkActor>::New();
tubesActor->SetMapper(tubesMapper);
vtkSmartPointer<vtkGradientFilter> gradients = vtkSmartPointer<vtkGradientFilter>::New();
gradients->SetInputData(marched); // ->SetInputConnection(reader->GetOutputPort());
vtkSmartPointer<vtkAssignAttribute> vectors = vtkSmartPointer<vtkAssignAttribute>::New();
vectors->SetInputConnection(gradients->GetOutputPort());
vectors->Assign("Gradients", vtkDataSetAttributes::VECTORS, vtkAssignAttribute::POINT_DATA);
vtkSmartPointer<vtkArrowSource> arrow = vtkSmartPointer<vtkArrowSource>::New();
vtkSmartPointer<vtkGlyph3D> glyphs = vtkSmartPointer<vtkGlyph3D>::New();
glyphs->SetInputConnection(0, vectors->GetOutputPort());
glyphs->SetInputConnection(1, arrow->GetOutputPort());
glyphs->ScalingOn();
glyphs->SetScaleModeToScaleByVector();
glyphs->SetScaleFactor(0.25);
glyphs->OrientOn();
glyphs->ClampingOff();
glyphs->SetVectorModeToUseVector();
glyphs->SetIndexModeToOff();
vtkSmartPointer<vtkPolyDataMapper> glyphMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
glyphMapper->SetInputConnection(glyphs->GetOutputPort());
glyphMapper->ScalarVisibilityOff();
vtkSmartPointer<vtkActor> glyphActor = vtkSmartPointer<vtkActor>::New();
glyphActor->SetMapper(glyphMapper);
vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
renderer->AddActor(tubesActor);
renderer->AddActor(glyphActor);
renderer->SetBackground(0.328125, 0.347656, 0.425781);
vtkSmartPointer<vtkRenderWindow> renwin =
vtkSmartPointer<vtkRenderWindow>::New();
renwin->AddRenderer(renderer);
renwin->SetSize(600, 600);
renderer->ResetCamera();
vtkCamera* camera = renderer->GetActiveCamera();
camera->Elevation(-80.0);
camera->OrthogonalizeViewUp();
camera->Azimuth(135.0);
vtkSmartPointer<vtkRenderWindowInteractor> iren =
vtkSmartPointer<vtkRenderWindowInteractor>::New();
iren->SetRenderWindow(renwin);
renwin->Render();
iren->Initialize();
iren->Start();
return EXIT_SUCCESS;
}
Here is the result: