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Triangle

vtk-examples/Cxx/GeometricObjects/Triangle


Description

The triangle is a primary two-dimensional cell. The triangle is defined by a counterclockwise ordered list of three points. The order of the points specifies the direction of the surface normal using the right-hand rule.

Other languages

See (Python), (Java), (CSharp)

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

Triangle.cxx

#include <vtkActor.h>
#include <vtkCellArray.h>
#include <vtkNamedColors.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartPointer.h>
#include <vtkTriangle.h>

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

  // Create a triangle
  vtkNew<vtkPoints> points;
  points->InsertNextPoint(1.0, 0.0, 0.0);
  points->InsertNextPoint(0.0, 0.0, 0.0);
  points->InsertNextPoint(0.0, 1.0, 0.0);

  vtkNew<vtkTriangle> triangle;
  triangle->GetPointIds()->SetId(0, 0);
  triangle->GetPointIds()->SetId(1, 1);
  triangle->GetPointIds()->SetId(2, 2);

  vtkNew<vtkCellArray> triangles;
  triangles->InsertNextCell(triangle);

  // Create a polydata object
  vtkNew<vtkPolyData> trianglePolyData;

  // Add the geometry and topology to the polydata
  trianglePolyData->SetPoints(points);
  trianglePolyData->SetPolys(triangles);

  // Create mapper and actor
  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputData(trianglePolyData);

  vtkNew<vtkActor> actor;
  actor->GetProperty()->SetColor(colors->GetColor3d("PeachPuff").GetData());
  actor->SetMapper(mapper);

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

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

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

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(Triangle)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping Triangle: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(Triangle MACOSX_BUNDLE Triangle.cxx )
  target_link_libraries(Triangle PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(Triangle MACOSX_BUNDLE Triangle.cxx )
  target_link_libraries(Triangle PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS Triangle
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build Triangle

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

cd Triangle/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:

./Triangle

WINDOWS USERS

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