VTK/Examples/TriangleColoredPoints

#include <vtkSmartPointer.h>
#include <vtkPoints.h>
#include <vtkXMLPolyDataWriter.h>
#include <vtkPolyData.h>
#include <vtkPointData.h>
#include <vtkCellArray.h>
#include <vtkTriangle.h>
 
int main(int argc, char *argv[])
{
  //setup points
  vtkSmartPointer<vtkPoints> points = 
      vtkSmartPointer<vtkPoints>::New();
  points->InsertNextPoint ( 1.0, 0.0, 0.0 );
  points->InsertNextPoint ( 0.0, 0.0, 0.0 );
  points->InsertNextPoint ( 0.0, 1.0, 0.0 );
 
  //define some colors
  unsigned char red[3] = {255, 0, 0};
  unsigned char green[3] = {0, 255, 0};
  unsigned char blue[3] = {0, 0, 255};
 
  //setup the colors array
  vtkSmartPointer<vtkUnsignedCharArray> colors = 
      vtkSmartPointer<vtkUnsignedCharArray>::New();
  colors->SetNumberOfComponents ( 3 );
  colors->SetName ( "Colors" );
 
  //add the three colors we have created to the array
  colors->InsertNextTupleValue ( red );
  colors->InsertNextTupleValue ( green );
  colors->InsertNextTupleValue ( blue );
 
  //create the triangle
  vtkSmartPointer<vtkCellArray> triangles = 
      vtkSmartPointer<vtkCellArray>::New();
  vtkSmartPointer<vtkTriangle> triangle = 
      vtkSmartPointer<vtkTriangle>::New();
  triangle->GetPointIds()->SetId ( 0, 0 );
  triangle->GetPointIds()->SetId ( 1, 1 );
  triangle->GetPointIds()->SetId ( 2, 2 );
  triangles->InsertNextCell ( triangle );
 
  //create a polydata object and add everything to it
  vtkSmartPointer<vtkPolyData> polydata = 
      vtkSmartPointer<vtkPolyData>::New();
  polydata->SetPoints ( points );
  polydata->SetPolys ( triangles );
  polydata->GetPointData()->SetScalars ( colors );
 
  //write the polydata to a file
  vtkSmartPointer<vtkXMLPolyDataWriter> writer = 
      vtkSmartPointer<vtkXMLPolyDataWriter>::New();
  writer->SetFileName ( "TriangleColoredPoints.vtp" );
  writer->SetInput ( polydata );
  writer->Write();
 
  return EXIT_SUCCESS;
}