VTK/Examples/Cxx/Filtering/Delaunay2D

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VTK Examples Baseline Filtering TestDelaunay2D.png

This example generates a set of points aligned with an XY grid with random heights (z values). The Delaunay2D filter "magically" knows how to triangulate this type of point set because it projects the points by default onto the XY axis and then performs a 2D Delaunay triangulation. The result is a mesh on the input points.

Delaunay2D.cxx

#include <vtkVersion.h>
#include <vtkCellArray.h>
#include <vtkPoints.h>
#include <vtkTriangle.h>
#include <vtkPolyData.h>
#include <vtkPointData.h>
#include <vtkLine.h>
#include <vtkCellLocator.h>
#include <vtkSmartPointer.h>
#include <vtkDelaunay2D.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkProperty.h>
#include <vtkVertexGlyphFilter.h>
 
int main(int, char *[])
{
  // Create a set of heighs on a grid.
  // This is often called a "terrain map".
  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, (x+y)/(y+1));
      }
    }
 
  // Add the grid points to a polydata object
  vtkSmartPointer<vtkPolyData> polydata =
    vtkSmartPointer<vtkPolyData>::New();
  polydata->SetPoints(points);
 
  // 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();
 
  // Visualize
  vtkSmartPointer<vtkPolyDataMapper> meshMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  meshMapper->SetInputConnection(delaunay->GetOutputPort());
 
  vtkSmartPointer<vtkActor> meshActor =
    vtkSmartPointer<vtkActor>::New();
  meshActor->SetMapper(meshMapper);
 
  vtkSmartPointer<vtkVertexGlyphFilter> glyphFilter =
    vtkSmartPointer<vtkVertexGlyphFilter>::New();
#if VTK_MAJOR_VERSION <= 5
  glyphFilter->SetInputConnection(polydata->GetProducerPort());
#else
  glyphFilter->SetInputData(polydata);
#endif
  glyphFilter->Update();
 
  vtkSmartPointer<vtkPolyDataMapper> pointMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  pointMapper->SetInputConnection(glyphFilter->GetOutputPort());
 
  vtkSmartPointer<vtkActor> pointActor =
    vtkSmartPointer<vtkActor>::New();
  pointActor->GetProperty()->SetColor(1,0,0);
  pointActor->GetProperty()->SetPointSize(3);
  pointActor->SetMapper(pointMapper);
 
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);
 
  renderer->AddActor(meshActor);
  renderer->AddActor(pointActor);
  renderer->SetBackground(.3, .6, .3); // Background color green
 
  renderWindow->Render();
  renderWindowInteractor->Start();
 
  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.6)
 
PROJECT(Delaunay)
 
FIND_PACKAGE(VTK REQUIRED)
INCLUDE(${VTK_USE_FILE})
 
ADD_EXECUTABLE(Delaunay Delaunay.cxx)
TARGET_LINK_LIBRARIES(Delaunay vtkHybrid)
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