# Triangle

VTKExamples/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 VTKExamplesProject 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");
vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
vtkSmartPointer<vtkRenderWindowInteractor>::New();
renderWindowInteractor->SetRenderWindow(renderWindow);

// Add the actors to the scene
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
vtkRenderingCore
vtkRenderingFreeType
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 ()


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.