Triangle

VTKEx/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 simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, 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 *[])
{
  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

  // Create a triangle
  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<vtkTriangle> triangle =
    vtkSmartPointer<vtkTriangle>::New();
  triangle->GetPointIds()->SetId ( 0, 0 );
  triangle->GetPointIds()->SetId ( 1, 1 );
  triangle->GetPointIds()->SetId ( 2, 2 );

  vtkSmartPointer<vtkCellArray> triangles =
    vtkSmartPointer<vtkCellArray>::New();
  triangles->InsertNextCell ( triangle );

  // Create a polydata object
  vtkSmartPointer<vtkPolyData> trianglePolyData =
    vtkSmartPointer<vtkPolyData>::New();

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

  // Create mapper and actor
  vtkSmartPointer<vtkPolyDataMapper> mapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputData(trianglePolyData);

  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->GetProperty()->SetColor(colors->GetColor3d("Cyan").GetData());
  actor->SetMapper(mapper);

  // Create a renderer, render window, and an interactor
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->SetWindowName("Triangle");
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  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 
  vtkvtkCommonColor
  vtkvtkCommonCore
  vtkvtkCommonDataModel
  vtkvtkInteractionStyle
  vtkvtkRenderingContextOpenGL2
  vtkvtkRenderingCore
  vtkvtkRenderingFreeType
  vtkvtkRenderingGL2PSOpenGL2
  vtkvtkRenderingOpenGL2 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.