# PolyLine1

VTKExamples/Cxx/GeometricObjects/PolyLine1

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### Code¶

PolyLine1.cxx

#include <vtkActor.h>
#include <vtkCellArray.h>
#include <vtkMath.h>
#include <vtkNamedColors.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <algorithm>
#include <array>
#include <cmath>
#include <vector>

int main(int, char* [])
{

vtkSmartPointer<vtkNamedColors> colors =
vtkSmartPointer<vtkNamedColors>::New();

// Set the background color.
std::array<unsigned char , 4> bkg{{26, 51, 102, 255}};
colors->SetColor("BkgColor", bkg.data());

// vtkPoints represents 3D points. The data model for vtkPoints is an array of
// vx-vy-vz triplets accessible by (point or cell) id.
vtkSmartPointer<vtkPoints> points =
vtkSmartPointer<vtkPoints>::New();
points->SetNumberOfPoints(6);
double c = std::cos(vtkMath::Pi() / 6); // helper variable
points->SetPoint(0, 0.0, -1.0, 0.0);
points->SetPoint(1, c, -0.5, 0.0);
points->SetPoint(2, c, 0.5, 0.0);
points->SetPoint(3, 0.0, 1.0, 0.0);
points->SetPoint(4, -c, 0.5, 0.0);
points->SetPoint(5, -c, -0.5, 0.0);

// vtkCellArray is a supporting object that explicitly represents cell
// connectivity.
// The cell array structure is a raw integer list of the form:
// (n,id1,id2,...,idn, n,id1,id2,...,idn, ...) where n is the number of points
// in
// the cell, and id is a zero-offset index into an associated point list.
vtkSmartPointer<vtkCellArray> lines =
vtkSmartPointer<vtkCellArray>::New();
lines->InsertNextCell(7);
lines->InsertCellPoint(0);
lines->InsertCellPoint(1);
lines->InsertCellPoint(2);
lines->InsertCellPoint(3);
lines->InsertCellPoint(4);
lines->InsertCellPoint(5);
lines->InsertCellPoint(0);

// vtkPolyData is a data object that is a concrete implementation of
// vtkDataSet.
// vtkPolyData represents a geometric structure consisting of vertices, lines,
// polygons, and/or triangle strips
vtkSmartPointer<vtkPolyData> polygon =
vtkSmartPointer<vtkPolyData>::New();
polygon->SetPoints(points);
polygon->SetLines(lines);

// vtkPolyDataMapper is a class that maps polygonal data (i.e., vtkPolyData)
// to graphics primitives
vtkSmartPointer<vtkPolyDataMapper> polygonMapper =
vtkSmartPointer<vtkPolyDataMapper>::New();
polygonMapper->SetInputData(polygon);
polygonMapper->Update();

// Create an actor to represent the polygon. The actor orchestrates rendering
// of
// the mapper's graphics primitives. An actor also refers to properties via a
// vtkProperty instance, and includes an internal transformation matrix. We
// set this actor's mapper to be polygonMapper which we created above.
vtkSmartPointer<vtkActor> polygonActor =
vtkSmartPointer<vtkActor>::New();
polygonActor->SetMapper(polygonMapper);
polygonActor->GetProperty()->SetColor(
colors->GetColor3d("AliceBlue").GetData());

// Create the Renderer and assign actors to it. A renderer is like a
// viewport. It is part or all of a window on the screen and it is
// responsible for drawing the actors it has.  We also set the
// background color here.
vtkSmartPointer<vtkRenderer> ren =
vtkSmartPointer<vtkRenderer>::New();
ren->SetBackground(colors->GetColor3d("BkgColor").GetData());

// Automatically set up the camera based on the visible actors.
// The camera will reposition itself to view the center point of the actors,
// and move along its initial view plane normal
// (i.e., vector defined from camera position to focal point) so that all of
// the
// actors can be seen.
ren->ResetCamera();

// Finally we create the render window which will show up on the screen
// We put our renderer into the render window using AddRenderer. We
// also set the size to be 300 pixels by 300.
vtkSmartPointer<vtkRenderWindow> renWin =
vtkSmartPointer<vtkRenderWindow>::New();
renWin->SetWindowName("OrderedPolyLine");
renWin->SetSize(300, 300);

// The vtkRenderWindowInteractor class watches for events (e.g., keypress,
// mouse) in the vtkRenderWindow. These events are translated into
// event invocations that VTK understands (see VTK/Common/vtkCommand.h
// for all events that VTK processes). Then observers of these VTK
// events can process them as appropriate.
vtkSmartPointer<vtkRenderWindowInteractor> iren =
vtkSmartPointer<vtkRenderWindowInteractor>::New();
iren->SetRenderWindow(renWin);
renWin->Render();
iren->Initialize();
iren->Start();

return EXIT_SUCCESS;

}


### CMakeLists.txt¶

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(PolyLine1)

find_package(VTK COMPONENTS
vtkCommonColor
vtkCommonCore
vtkCommonDataModel
vtkInteractionStyle
vtkRenderingContextOpenGL2
vtkRenderingCore
vtkRenderingFreeType
vtkRenderingGL2PSOpenGL2
vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
message("Skipping PolyLine1: ${VTK_NOT_FOUND_MESSAGE}") return () endif() message (STATUS "VTK_VERSION:${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
# old system
include(${VTK_USE_FILE}) add_executable(PolyLine1 MACOSX_BUNDLE PolyLine1.cxx ) target_link_libraries(PolyLine1 PRIVATE${VTK_LIBRARIES})
else ()
# include all components
target_link_libraries(PolyLine1 PRIVATE ${VTK_LIBRARIES}) # vtk_module_autoinit is needed vtk_module_autoinit( TARGETS PolyLine1 MODULES${VTK_LIBRARIES}
)
endif ()


cd PolyLine1/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:

./PolyLine1


WINDOWS USERS

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