VTK/Tutorials/TriangleGeometryPolygon

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TrianglePolygon.cxx

<source lang="cpp">

  1. include <vtkCellArray.h>
  2. include <vtkSmartPointer.h>
  3. include <vtkPoints.h>
  4. include <vtkXMLPolyDataWriter.h>
  5. include <vtkPolyData.h>
  6. include <vtkTriangle.h>

int main(int argc, char *argv[]) {

 //setup points (geometry)
 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 );
 vtkSmartPointer<vtkCellArray> triangles = vtkSmartPointer<vtkCellArray>::New();
 //create a triangle on the three points in the polydata
 vtkSmartPointer<vtkTriangle> triangle = vtkSmartPointer<vtkTriangle>::New();
 //Unfortunately in this simple example the following lines are ambiguous.
 //The first 0 is the index of the triangle vertex which is ALWAYS 0-2.
 //The second 0 is the index into the point (geometry) array, so this can range from 0-(NumPoints-1)
 //i.e. a more general statement is triangle->GetPointIds()->SetId(0, PointId);
 triangle->GetPointIds()->SetId ( 0, 0 );
 triangle->GetPointIds()->SetId ( 1, 1 );
 triangle->GetPointIds()->SetId ( 2, 2 );
 //add the triangle to the list of triangles (in this case there is only 1)
 triangles->InsertNextCell ( triangle );
 //create a polydata object
 vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New();
 //add the geometry and topology to the polydata
 polydata->SetPoints ( points );
 polydata->SetPolys ( triangles );
 //write the polydata to a file
 vtkSmartPointer<vtkXMLPolyDataWriter> writer = vtkSmartPointer<vtkXMLPolyDataWriter>::New();
 writer->SetFileName ( "Triangle.vtp" );
  1. if VTK_MAJOR_VERSION <= 5
 writer->SetInput ( polydata );
  1. else
 writer->SetInputData ( polydata );
  1. endif
 writer->Write();
 return EXIT_SUCCESS;

}

</source>

CMakeLists.txt

<source lang="cmake"> cmake_minimum_required(VERSION 2.6)

project(TrianglePolygon)

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

add_executable(TrianglePolygon TrianglePolygon.cxx) if(VTK_LIBRARIES)

 target_link_libraries(TrianglePolygon ${VTK_LIBRARIES})

else()

 target_link_libraries(TrianglePolygon vtkHybrid)

endif()

</source>