OpenVROrientedCylinder

#include <vtkActor.h>
#include <vtkCylinderSource.h>
#include <vtkMath.h>
#include <vtkMinimalStandardRandomSequence.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkOpenVRRenderWindow.h>
#include <vtkOpenVRRenderWindowInteractor.h>
#include <vtkOpenVRRenderer.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkSphereSource.h>
#include <vtkTransform.h>
#include <vtkTransformPolyDataFilter.h>

#include <array>

#define USER_MATRIX

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

  // Set the background color.
  std::array<unsigned char, 4> bkg{{26, 51, 77, 255}};
  colors->SetColor("BkgColor", bkg.data());

  // Create a cylinder.
  // Cylinder height vector is (0,1,0).
  // Cylinder center is in the middle of the cylinder
  vtkNew<vtkCylinderSource> cylinderSource;
  cylinderSource->SetResolution(15);

  // Generate a random start and end point
  double startPoint[3];
  double endPoint[3];
  vtkNew<vtkMinimalStandardRandomSequence> rng;
  rng->SetSeed(8775070); // For testing.
  for (auto i = 0; i < 3; ++i)
  {
    rng->Next();
    startPoint[i] = rng->GetRangeValue(-10, 10);
    rng->Next();
    endPoint[i] = rng->GetRangeValue(-10, 10);
  }

  // Compute a basis
  double normalizedX[3];
  double normalizedY[3];
  double normalizedZ[3];

  // The X axis is a vector from start to end
  vtkMath::Subtract(endPoint, startPoint, normalizedX);
  double length = vtkMath::Norm(normalizedX);
  vtkMath::Normalize(normalizedX);

  // The Z axis is an arbitrary vector cross X
  double arbitrary[3];
  for (auto i = 0; i < 3; ++i)
  {
    rng->Next();
    arbitrary[i] = rng->GetRangeValue(-10, 10);
  }
  vtkMath::Cross(normalizedX, arbitrary, normalizedZ);
  vtkMath::Normalize(normalizedZ);

  // The Y axis is Z cross X
  vtkMath::Cross(normalizedZ, normalizedX, normalizedY);
  vtkNew<vtkMatrix4x4> matrix;

  // Create the direction cosine matrix
  matrix->Identity();
  for (unsigned int i = 0; i < 3; i++)
  {
    matrix->SetElement(i, 0, normalizedX[i]);
    matrix->SetElement(i, 1, normalizedY[i]);
    matrix->SetElement(i, 2, normalizedZ[i]);
  }

  // Apply the transforms
  vtkNew<vtkTransform> transform;
  transform->Translate(startPoint);   // translate to starting point
  transform->Concatenate(matrix);     // apply direction cosines
  transform->RotateZ(-90.0);          // align cylinder to x axis
  transform->Scale(1.0, length, 1.0); // scale along the height vector
  transform->Translate(0, .5, 0);     // translate to start of cylinder

  // Transform the polydata
  vtkNew<vtkTransformPolyDataFilter> transformPD;
  transformPD->SetTransform(transform);
  transformPD->SetInputConnection(cylinderSource->GetOutputPort());

  // Create a mapper and actor for the cylinder
  vtkNew<vtkPolyDataMapper> mapper;
  vtkNew<vtkActor> actor;
#ifdef USER_MATRIX
  mapper->SetInputConnection(cylinderSource->GetOutputPort());
  actor->SetUserMatrix(transform->GetMatrix());
#else
  mapper->SetInputConnection(transformPD->GetOutputPort());
#endif
  actor->SetMapper(mapper);
  actor->GetProperty()->SetColor(colors->GetColor3d("Cyan").GetData());

  // Create spheres for start and end point
  vtkNew<vtkSphereSource> sphereStartSource;
  sphereStartSource->SetCenter(startPoint);
  sphereStartSource->SetRadius(0.8);
  vtkNew<vtkPolyDataMapper> sphereStartMapper;
  sphereStartMapper->SetInputConnection(sphereStartSource->GetOutputPort());
  vtkNew<vtkActor> sphereStart;
  sphereStart->SetMapper(sphereStartMapper);
  sphereStart->GetProperty()->SetColor(colors->GetColor3d("Yellow").GetData());

  vtkNew<vtkSphereSource> sphereEndSource;
  sphereEndSource->SetCenter(endPoint);
  sphereEndSource->SetRadius(0.8);
  vtkNew<vtkPolyDataMapper> sphereEndMapper;
  sphereEndMapper->SetInputConnection(sphereEndSource->GetOutputPort());
  vtkNew<vtkActor> sphereEnd;
  sphereEnd->SetMapper(sphereEndMapper);
  sphereEnd->GetProperty()->SetColor(colors->GetColor3d("Magenta").GetData());

  // Create a renderer, render window, and interactor
  vtkNew<vtkOpenVRRenderer> renderer;
  vtkNew<vtkOpenVRRenderWindow> renderWindow;
  renderWindow->Initialize();
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("OpenVROrientedCylinder");
  vtkNew<vtkOpenVRRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add the actor to the scene
  renderer->AddActor(actor);
  renderer->AddActor(sphereStart);
  renderer->AddActor(sphereEnd);
  renderer->SetBackground(colors->GetColor3d("BkgColor").GetData());

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

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(OpenVROrientedCylinder)

find_package(VTK COMPONENTS 
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "OpenVROrientedCylinder: Unable to find the VTK build folder.")
endif()

# 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(OpenVROrientedCylinder MACOSX_BUNDLE OpenVROrientedCylinder.cxx )
  target_link_libraries(OpenVROrientedCylinder PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS OpenVROrientedCylinder
  MODULES ${VTK_LIBRARIES}
)

cd OpenVROrientedCylinder/build

cmake ..

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

make

./OpenVROrientedCylinder