VTK/Examples/Cxx/GeometricObjects/ColoredLines

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VTK Examples Baseline GeometricObjects TestColoredLines.png

Displays two lines, each with a different color. See also VTK/Examples/Cxx/GeometricObjects/LongLine.

ColoredLines.cxx

#include <vtkVersion.h>
#include <vtkSmartPointer.h>
#include <vtkCellArray.h>
#include <vtkCellData.h>
#include <vtkUnsignedCharArray.h>
#include <vtkPoints.h>
#include <vtkLine.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.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);
  
  
  // Create two colors - one for each line
  unsigned char red[3] = { 255, 0, 0 };
  unsigned char green[3] = { 0, 255, 0 };
  
  // Create a vtkUnsignedCharArray container and store the colors in it
  vtkSmartPointer<vtkUnsignedCharArray> colors =
    vtkSmartPointer<vtkUnsignedCharArray>::New();
  colors->SetNumberOfComponents(3);
  colors->InsertNextTupleValue(red);
  colors->InsertNextTupleValue(green);
  
  // 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();

#if VTK_MAJOR_VERSION <= 5
  mapper->SetInput(linesPolyData);
#else
   mapper->SetInputData(linesPolyData);
#endif
  
  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
  
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  renderer->AddActor(actor);
  
  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;
}

Please try the new VTKExamples website.

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)

if(VTK_LIBRARIES)
  target_link_libraries(ColoredLines ${VTK_LIBRARIES})
else()
  target_link_libraries(ColoredLines vtkHybrid vtkWidgets)
endif()

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.