Polygon
vtk-examples/Cxx/GeometricObjects/Polygon
Description¶
The polygon is a primary two-dimensional cell. The polygon is defined by an ordered list of three or more points lying in a plane. The polygon normal is implicitly defined by a counterclockwise ordering of its points using the right-hand rule.
The polygon may be nonconvex, but may not have internal loops, and it cannot self-intersect. The polygon has n edges, where n is the number of points in the polygon.
Question
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Code¶
Polygon.cxx
#include <vtkActor.h>
#include <vtkCellArray.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkPolygon.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
int main(int, char*[])
{
vtkNew<vtkNamedColors> colors;
// Setup four points
vtkNew<vtkPoints> points;
points->InsertNextPoint(0.0, 0.0, 0.0);
points->InsertNextPoint(1.0, 0.0, 0.0);
points->InsertNextPoint(1.0, 1.0, 0.0);
points->InsertNextPoint(0.0, 1.0, 0.0);
// Create the polygon
vtkNew<vtkPolygon> polygon;
polygon->GetPointIds()->SetNumberOfIds(4); // make a quad
polygon->GetPointIds()->SetId(0, 0);
polygon->GetPointIds()->SetId(1, 1);
polygon->GetPointIds()->SetId(2, 2);
polygon->GetPointIds()->SetId(3, 3);
// Add the polygon to a list of polygons
vtkNew<vtkCellArray> polygons;
polygons->InsertNextCell(polygon);
// Create a PolyData
vtkNew<vtkPolyData> polygonPolyData;
polygonPolyData->SetPoints(points);
polygonPolyData->SetPolys(polygons);
// Create a mapper and actor
vtkNew<vtkPolyDataMapper> mapper;
mapper->SetInputData(polygonPolyData);
vtkNew<vtkActor> actor;
actor->SetMapper(mapper);
actor->GetProperty()->SetColor(colors->GetColor3d("Silver").GetData());
// Visualize
vtkNew<vtkRenderer> renderer;
vtkNew<vtkRenderWindow> renderWindow;
renderWindow->SetWindowName("Polygon");
renderWindow->AddRenderer(renderer);
vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
renderWindowInteractor->SetRenderWindow(renderWindow);
renderer->AddActor(actor);
renderer->SetBackground(colors->GetColor3d("Salmon").GetData());
renderWindow->Render();
renderWindowInteractor->Start();
return EXIT_SUCCESS;
}
CMakeLists.txt¶
cmake_minimum_required(VERSION 3.12 FATAL_ERROR)
project(Polygon)
find_package(VTK COMPONENTS
vtkCommonColor
vtkCommonCore
vtkCommonDataModel
vtkInteractionStyle
vtkRenderingContextOpenGL2
vtkRenderingCore
vtkRenderingFreeType
vtkRenderingGL2PSOpenGL2
vtkRenderingOpenGL2
QUIET
)
if (NOT VTK_FOUND)
message("Skipping Polygon: ${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(Polygon MACOSX_BUNDLE Polygon.cxx )
target_link_libraries(Polygon PRIVATE ${VTK_LIBRARIES})
else()
# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(Polygon MACOSX_BUNDLE Polygon.cxx )
target_link_libraries(Polygon PRIVATE ${VTK_LIBRARIES})
# vtk_module_autoinit is needed
vtk_module_autoinit(
TARGETS Polygon
MODULES ${VTK_LIBRARIES}
)
endif()
Download and Build Polygon¶
Click here to download Polygon and its CMakeLists.txt file. Once the tarball Polygon.tar has been downloaded and extracted,
cd Polygon/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:
./Polygon
WINDOWS USERS
Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.