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ScaleVertices

vtk-examples/Cxx/Graphs/ScaleVertices

Description

Scale the vertices based on a data array.

Other languages

See (Python)

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

ScaleVertices.cxx

#include <vtkDataSetAttributes.h>
#include <vtkFloatArray.h>
#include <vtkForceDirectedLayoutStrategy.h>
#include <vtkGraphLayoutView.h>
#include <vtkGraphToGlyphs.h>
#include <vtkLookupTable.h>
#include <vtkMutableUndirectedGraph.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderedGraphRepresentation.h>
#include <vtkRenderer.h>
#include <vtkViewTheme.h>

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  vtkNew<vtkMutableUndirectedGraph> g;

  vtkIdType v1 = g->AddVertex();
  vtkIdType v2 = g->AddVertex();

  g->AddEdge(v1, v2);
  g->AddEdge(v1, v2);

  vtkNew<vtkFloatArray> scales;
  scales->SetNumberOfComponents(1);
  scales->SetName("Scales");
  scales->InsertNextValue(2.0);
  scales->InsertNextValue(5.0);

  // Add the scale array to the graph
  g->GetVertexData()->AddArray(scales);

  // Create the color array
  vtkNew<vtkIntArray> vertexColors;
  vertexColors->SetNumberOfComponents(1);
  vertexColors->SetName("Color");

  vtkNew<vtkLookupTable> lookupTable;
  lookupTable->SetNumberOfTableValues(2);
  lookupTable->SetTableValue(0, colors->GetColor4d("Yellow").GetData());
  lookupTable->SetTableValue(1, colors->GetColor4d("Lime").GetData());
  lookupTable->Build();

  vertexColors->InsertNextValue(0);
  vertexColors->InsertNextValue(1);

  // Add the color array to the graph
  g->GetVertexData()->AddArray(vertexColors);

  // Visualize

  vtkNew<vtkViewTheme> theme;
  theme->SetPointLookupTable(lookupTable);

  vtkNew<vtkForceDirectedLayoutStrategy> forceDirected;

  vtkNew<vtkGraphLayoutView> layoutView;
  layoutView->AddRepresentationFromInput(g);
  // If we create a layout object directly, just set the pointer to this method.
  // graphLayoutView->SetLayoutStrategy(forceDirected);
  layoutView->SetLayoutStrategyToForceDirected();
  layoutView->ApplyViewTheme(theme);
  layoutView->ScaledGlyphsOn();
  layoutView->SetScalingArrayName("Scales");
  layoutView->SetVertexColorArrayName("Color");
  layoutView->ColorVerticesOn();
  dynamic_cast<vtkRenderedGraphRepresentation*>(layoutView->GetRepresentation())
      ->SetGlyphType(vtkGraphToGlyphs::CIRCLE);
  layoutView->GetRenderer()->SetBackground(
      colors->GetColor3d("Navy").GetData());
  layoutView->GetRenderer()->SetBackground2(
      colors->GetColor3d("MidnightBlue").GetData());
  layoutView->GetRenderWindow()->SetWindowName("ScaleVertices");
  layoutView->Render();
  layoutView->ResetCamera();
  layoutView->GetInteractor()->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(ScaleVertices)

find_package(VTK COMPONENTS 
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "ScaleVertices: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(ScaleVertices MACOSX_BUNDLE ScaleVertices.cxx )
  target_link_libraries(ScaleVertices PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS ScaleVertices
  MODULES ${VTK_LIBRARIES}
)

Download and Build ScaleVertices

Click here to download ScaleVertices and its CMakeLists.txt file. Once the tarball ScaleVertices.tar has been downloaded and extracted,

cd ScaleVertices/build

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./ScaleVertices

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.