# TriangulateTerrainMap

vtk-examples/Cxx/Filtering/TriangulateTerrainMap

### Description¶

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

Other languages

See (Python)

Question

### Code¶

TriangulateTerrainMap.cxx

#include <vtkActor.h>
#include <vtkDelaunay2D.h>
#include <vtkMath.h>
#include <vtkMinimalStandardRandomSequence.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkVertexGlyphFilter.h>

int main(int, char*[])
{
vtkNew<vtkNamedColors> colors;

// Create points on an XY grid with random Z coordinate
vtkNew<vtkPoints> points;

unsigned int gridSize = 10;
unsigned int seed = 0;
vtkNew<vtkMinimalStandardRandomSequence> randomSequence;
randomSequence->Initialize(seed);
for (unsigned int x = 0; x < gridSize; x++)
{
for (unsigned int y = 0; y < gridSize; y++)
{
auto d = randomSequence->GetValue();
randomSequence->Next();
points->InsertNextPoint(x, y, d * 3.0);
}
}

// Add the grid points to a polydata object
vtkNew<vtkPolyData> polydata;
polydata->SetPoints(points);

vtkNew<vtkVertexGlyphFilter> glyphFilter;
glyphFilter->SetInputData(polydata);
glyphFilter->Update();

// Create a mapper and actor
vtkNew<vtkPolyDataMapper> pointsMapper;
pointsMapper->SetInputConnection(glyphFilter->GetOutputPort());

vtkNew<vtkActor> pointsActor;
pointsActor->SetMapper(pointsMapper);
pointsActor->GetProperty()->SetPointSize(3);
pointsActor->GetProperty()->SetColor(colors->GetColor3d("Red").GetData());
// Triangulate the grid points
vtkNew<vtkDelaunay2D> delaunay;
delaunay->SetInputData(polydata);
delaunay->Update();

// Create a mapper and actor
vtkNew<vtkPolyDataMapper> triangulatedMapper;
triangulatedMapper->SetInputConnection(delaunay->GetOutputPort());

vtkNew<vtkActor> triangulatedActor;
triangulatedActor->SetMapper(triangulatedMapper);

// Create a renderer, render window, and interactor
vtkNew<vtkRenderer> renderer;
vtkNew<vtkRenderWindow> renderWindow;
vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
renderWindowInteractor->SetRenderWindow(renderWindow);

// Add the actor to the scene
renderer->SetBackground(colors->GetColor3d("Green").GetData());

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

return EXIT_SUCCESS;
}


### CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(TriangulateTerrainMap)

find_package(VTK COMPONENTS
CommonColor
CommonCore
CommonDataModel
FiltersCore
FiltersGeneral
InteractionStyle
RenderingContextOpenGL2
RenderingCore
RenderingFreeType
RenderingGL2PSOpenGL2
RenderingOpenGL2
)

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


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

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