VTKのカメラ状態を保存・リストア

#include <iostream>

//VTK_MODULE_INITに必要
#include <vtkAutoInit.h>


#include <vtkSmartPointer.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>

//円筒とその表示に必要
#include <vtkCylinderSource.h>
#include <vtkPolyDataMapper.h>

#include <vtkCamera.h>
#include <vtkCommand.h>
#include <vtkRendererCollection.h>



#pragma comment(lib,"opengl32.lib")
#pragma comment(lib,"psapi.lib")
#pragma comment(lib,"dbghelp.lib")
#pragma comment(lib,"ws2_32.lib")


//必須
VTK_MODULE_INIT(vtkRenderingOpenGL2);
VTK_MODULE_INIT(vtkInteractionStyle);

struct CameraState {
    double Position[3];
    double FocalPoint[3];
    double ViewUp[3];
    double ClippingRange[2];
    double ViewAngle;
};

// カメラの状態を保存する関数
CameraState GetCameraState(vtkCamera* camera) {
    CameraState state;
    camera->GetPosition(state.Position);
    camera->GetFocalPoint(state.FocalPoint);
    camera->GetViewUp(state.ViewUp);
    camera->GetClippingRange(state.ClippingRange);
    state.ViewAngle = camera->GetViewAngle();
    return state;
}

// カメラの状態を復元する関数
void LoadCameraState(vtkCamera* camera, const CameraState& state) {
    camera->SetPosition(state.Position);
    camera->SetFocalPoint(state.FocalPoint);
    camera->SetViewUp(state.ViewUp);
    camera->SetClippingRange(state.ClippingRange);
    camera->SetViewAngle(state.ViewAngle);
}

// キーボード入力を処理
class MyCommand : public vtkCommand {
    CameraState camera_state;
public:
    static MyCommand* New() {
        return new MyCommand;
    }

    void SetMapper(vtkSmartPointer<vtkPolyDataMapper> mapper) {
        this->Mapper = mapper;
    }

    void Execute(vtkObject* caller, unsigned long eventId, void*) override {
        if (eventId == vtkCommand::KeyPressEvent) {
            vtkRenderWindowInteractor* interactor = dynamic_cast<vtkRenderWindowInteractor*>(caller);
            std::string key = interactor->GetKeySym();

            // 注意　デフォルト機能で E キーで終了してしまう

            // キー入力を取得
            if (key == "s") {

                // カメラの状態を保存
                vtkRenderer* renderer = interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer();
                vtkCamera* camera = renderer->GetActiveCamera();

                // cameraをcamera_stateに保存
                camera_state = GetCameraState(camera);

            }
            else if (key == "r") {

                // カメラの状態を復元
                vtkRenderer* renderer = interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer();
                vtkCamera* camera = renderer->GetActiveCamera();

                // camera_stateをcameraに復元
                LoadCameraState(camera, camera_state);

            }


            interactor->GetRenderWindow()->Render();
        }
    }

private:
    vtkSmartPointer<vtkPolyDataMapper> Mapper;
};




int main(int /*argc*/, char** /*argv*/)
{

    //////////////////////////////////////
    // Create a vtkCylinderSource
    vtkSmartPointer<vtkCylinderSource> cylinderSource = vtkSmartPointer<vtkCylinderSource>::New();
    cylinderSource->SetCenter(0.0, 0.0, 0.0);
    cylinderSource->SetRadius(5.0);
    cylinderSource->SetHeight(7.0);
    cylinderSource->SetResolution(100);

    //////////////////////////////////////
    // Create a mapper and actor
    vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
    mapper->SetInputConnection(cylinderSource->GetOutputPort());
    vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
    actor->SetMapper(mapper);

    //////////////////////////////////////
    auto renderer = vtkSmartPointer<vtkRenderer>::New();
    renderer->AddActor(actor);
    renderer->ResetCamera();

    //////////////////////////////////////
    auto interactor = vtkSmartPointer<vtkRenderWindowInteractor>::New();

    // キー入力で色を切り替えるコマンドを設定
    vtkSmartPointer<MyCommand> MyKeyboardAction = vtkSmartPointer<MyCommand>::New();
    MyKeyboardAction->SetMapper(mapper);
    interactor->AddObserver(vtkCommand::KeyPressEvent, MyKeyboardAction);

    //////////////////////////////////////
    auto renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
    renderWindow->AddRenderer(renderer);
    renderWindow->SetInteractor(interactor);
    renderWindow->Render();


    interactor->Start(); //イベントループへ入る

    return 0;
}