ColoredLines

#include <vtkActor.h>
#include <vtkCellArray.h>
#include <vtkCellData.h>
#include <vtkLine.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkUnsignedCharArray.h>

// For compatibility with new VTK generic data arrays.
#ifdef vtkGenericDataArray_h
#define InsertNextTupleValue InsertNextTypedTuple
#endif

int main(int, char*[])
{
  // Create the polydata where we will store all the geometric data
  vtkNew<vtkPolyData> linesPolyData;

  // Create three points
  double origin[3] = {0.0, 0.0, 0.0};
  double p0[3] = {1.0, 0.0, 0.0};
  double p1[3] = {0.0, 1.0, 0.0};

  // Create a vtkPoints container and store the points in it.
  vtkNew<vtkPoints> pts;
  pts->InsertNextPoint(origin);
  pts->InsertNextPoint(p0);
  pts->InsertNextPoint(p1);

  // Add the points to the polydata container.
  linesPolyData->SetPoints(pts);

  // Create the first line (between Origin and P0).
  vtkNew<vtkLine> line0;
  line0->GetPointIds()->SetId(
      0,
      0); // the second 0 is the index of the Origin in linesPolyData's points.
  line0->GetPointIds()->SetId(
      1, 1); // the second 1 is the index of P0 in linesPolyData's points.

  // Create the second line (between Origin and P1).
  vtkNew<vtkLine> line1;
  line1->GetPointIds()->SetId(
      0,
      0); // the second 0 is the index of the Origin in linesPolyData's points.
  line1->GetPointIds()->SetId(
      1, 2); // 2 is the index of P1 in linesPolyData's points.

  // Create a vtkCellArray container and store the lines in it.
  vtkNew<vtkCellArray> lines;
  lines->InsertNextCell(line0);
  lines->InsertNextCell(line1);

  // Add the lines to the polydata container.
  linesPolyData->SetLines(lines);

  vtkNew<vtkNamedColors> namedColors;

  // Create a vtkUnsignedCharArray container and store the colors in it.
  vtkNew<vtkUnsignedCharArray> colors;
  colors->SetNumberOfComponents(3);
  colors->InsertNextTupleValue(namedColors->GetColor3ub("Tomato").GetData());
  colors->InsertNextTupleValue(namedColors->GetColor3ub("Mint").GetData());

  // Color the lines.
  // SetScalars() automatically associates the values in the data array passed
  // as parameter to the elements in the same indices of the cell data array on
  // which it is called. This means the first component (red) of the colors
  // array is matched with the first component of the cell array (line 0) and
  // the second component (green) of the colors array is matched with the second
  // component of the cell array (line 1).
  linesPolyData->GetCellData()->SetScalars(colors);

  // Setup the visualization pipeline.
  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputData(linesPolyData);

  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);
  actor->GetProperty()->SetLineWidth(4);

  vtkNew<vtkRenderer> renderer;
  renderer->AddActor(actor);
  renderer->SetBackground(namedColors->GetColor3d("SlateGray").GetData());

  vtkNew<vtkRenderWindow> window;
  window->SetWindowName("Colored Lines");
  window->AddRenderer(renderer);

  vtkNew<vtkRenderWindowInteractor> interactor;
  interactor->SetRenderWindow(window);

  // Visualize
  window->Render();
  interactor->Start();

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(ColoredLines)

find_package(VTK COMPONENTS 
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "ColoredLines: 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(ColoredLines MACOSX_BUNDLE ColoredLines.cxx )
  target_link_libraries(ColoredLines PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS ColoredLines
  MODULES ${VTK_LIBRARIES}
)

cd ColoredLines/build

cmake ..

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

make

./ColoredLines