# ColoredLines

VTKExamples/Cxx/GeometricObjects/ColoredLines

### Description

Displays two lines, each with a different color.

Seealso

LongLine.

### Code

ColoredLines.cxx

    #include <vtkSmartPointer.h>
    #include <vtkLine.h>

    #include <vtkCellArray.h>
    #include <vtkCellData.h>
    #include <vtkUnsignedCharArray.h>
    #include <vtkPoints.h>
    #include <vtkPolyData.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkNamedColors.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
      vtkSmartPointer<vtkPolyData> linesPolyData =
        vtkSmartPointer<vtkPolyData>::New();

      // 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
      vtkSmartPointer<vtkPoints> pts =
        vtkSmartPointer<vtkPoints>::New();
      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)
      vtkSmartPointer<vtkLine> line0 =
        vtkSmartPointer<vtkLine>::New();
      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)
      vtkSmartPointer<vtkLine> line1 =
        vtkSmartPointer<vtkLine>::New();
      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
      vtkSmartPointer<vtkCellArray> lines =
        vtkSmartPointer<vtkCellArray>::New();
      lines->InsertNextCell(line0);
      lines->InsertNextCell(line1);

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

      vtkSmartPointer<vtkNamedColors> namedColors =
        vtkSmartPointer<vtkNamedColors>::New();

      // Create a vtkUnsignedCharArray container and store the colors in it
      vtkSmartPointer<vtkUnsignedCharArray> colors =
        vtkSmartPointer<vtkUnsignedCharArray>::New();
      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
      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
       mapper->SetInputData(linesPolyData);

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);
      actor->GetProperty()->SetLineWidth(4);

      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      renderer->AddActor(actor);
      renderer->SetBackground(namedColors->GetColor3d("SlateGray").GetData());

      vtkSmartPointer<vtkRenderWindow> window =
        vtkSmartPointer<vtkRenderWindow>::New();
      window->AddRenderer(renderer);

      vtkSmartPointer<vtkRenderWindowInteractor> interactor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      interactor->SetRenderWindow(window);

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

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(ColoredLines)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(ColoredLines MACOSX_BUNDLE ColoredLines.cxx )

    target_link_libraries(ColoredLines ${VTK_LIBRARIES})

### Download and Build ColoredLines

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

    cd ColoredLines/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:

    ./ColoredLines

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