# TriangulateTerrainMap

VTKExamples/Cxx/Filtering/TriangulateTerrainMap

### Description

This example generates heights (z value) on a 10x10 grid (a terrain map) and triangulates the points.

### Code

TriangulateTerrainMap.cxx

    #include <vtkVersion.h>
    #include <vtkSmartPointer.h>
    #include <vtkProperty.h>
    #include <vtkPoints.h>
    #include <vtkPolyData.h>
    #include <vtkPointData.h>
    #include <vtkDelaunay2D.h>
    #include <vtkMath.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkVertexGlyphFilter.h>

    int main(int, char *[])
    {
      // Create points on an XY grid with random Z coordinate
      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();

      unsigned int gridSize = 10;
      for(unsigned int x = 0; x < gridSize; x++)
      {
        for(unsigned int y = 0; y < gridSize; y++)
        {
          points->InsertNextPoint(x, y, vtkMath::Random(0.0, 3.0));
        }
      }

      // Add the grid points to a polydata object
      vtkSmartPointer<vtkPolyData> polydata =
        vtkSmartPointer<vtkPolyData>::New();
      polydata->SetPoints(points);

      vtkSmartPointer<vtkVertexGlyphFilter> glyphFilter =
        vtkSmartPointer<vtkVertexGlyphFilter>::New();
    #if VTK_MAJOR_VERSION <= 5
      glyphFilter->SetInputConnection(polydata->GetProducerPort());
    #else
      glyphFilter->SetInputData(polydata);
    #endif
      glyphFilter->Update();

      // Create a mapper and actor
      vtkSmartPointer<vtkPolyDataMapper> pointsMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      pointsMapper->SetInputConnection(glyphFilter->GetOutputPort());

      vtkSmartPointer<vtkActor> pointsActor =
        vtkSmartPointer<vtkActor>::New();
      pointsActor->SetMapper(pointsMapper);
      pointsActor->GetProperty()->SetPointSize(3);
      pointsActor->GetProperty()->SetColor(1,0,0);
      // Triangulate the grid points
      vtkSmartPointer<vtkDelaunay2D> delaunay =
        vtkSmartPointer<vtkDelaunay2D>::New();
    #if VTK_MAJOR_VERSION <= 5
      delaunay->SetInput(polydata);
    #else
      delaunay->SetInputData(polydata);
    #endif
      delaunay->Update();

      // Create a mapper and actor
      vtkSmartPointer<vtkPolyDataMapper> triangulatedMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      triangulatedMapper->SetInputConnection(delaunay->GetOutputPort());

      vtkSmartPointer<vtkActor> triangulatedActor =
        vtkSmartPointer<vtkActor>::New();
      triangulatedActor->SetMapper(triangulatedMapper);

      // Create a renderer, render window, and interactor
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      // Add the actor to the scene
      renderer->AddActor(pointsActor);
      renderer->AddActor(triangulatedActor);
      renderer->SetBackground(.3, .6, .3); // Background color green

      // Render and interact
      renderWindow->Render();
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(TriangulateTerrainMap)

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

    add_executable(TriangulateTerrainMap MACOSX_BUNDLE TriangulateTerrainMap.cxx)

    target_link_libraries(TriangulateTerrainMap ${VTK_LIBRARIES})

### Download and Build TriangulateTerrainMap

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

    cd TriangulateTerrainMap/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:

    ./TriangulateTerrainMap

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.