识别鼠标选中actor_vtkInteractorStyleTrackballActor

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开发环境：

1. Windows 11 家庭中文版
2. Microsoft Visual Studio Community 2019
3. VTK-9.3.0.rc0
4. vtk-example
5. 参考代码
6. 目的：学习与总结

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demo解决问题：通过自定义vtkInteractorStyle类中成员函数OnLeftButtonDown，判断鼠标当前选中的是哪个actor；同理可自定义鼠标右键、滚轮、键盘等事件
关键类：vtkInteractorStyleTrackballActor允许用户与场景中彼此独立的对象进行交互（旋转、平移等）；根据实际应用场景有如下常见替换对象：

vtkInteractorStyleTrackballActor	作用对象：actor; 形式：Trackball
vtkInteractorStyleTrackballCamera	作用对象：Camera; 形式：Trackball
vtkInteractorStyleJoystickActor	作用对象：actor; 形式：Joystick
vtkInteractorStyleJoystickCamera	作用对象：Camera; 形式：Joystick
vtkInteractorStyleImage	作用对象：vtkImageActor; 形式：绑定使相机的视图平面垂直于x-y平面
…	…

参考：vtkInteractorStyle详细介绍

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#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkCubeSource.h>
#include <vtkInteractorStyleTrackballActor.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSphereSource.h>namespace {// Handle mouse events.
class MouseInteractorStyle5 : public vtkInteractorStyleTrackballActor
{
public:static MouseInteractorStyle5* New();vtkTypeMacro(MouseInteractorStyle5, vtkInteractorStyleTrackballActor);virtual void OnLeftButtonDown() override{// Forward events.vtkInteractorStyleTrackballActor::OnLeftButtonDown();if (this->InteractionProp == this->Cube){std::cout << "Picked cube." << std::endl;}else if (this->InteractionProp == this->Sphere){std::cout << "Picked sphere." << std::endl;}}vtkActor* Cube;vtkActor* Sphere;
};vtkStandardNewMacro(MouseInteractorStyle5);} // namespaceint main(int, char*[])
{vtkNew<vtkNamedColors> colors;// Create a cube.vtkNew<vtkCubeSource> cubeSource;cubeSource->Update();vtkNew<vtkPolyDataMapper> cubeMapper;cubeMapper->SetInputConnection(cubeSource->GetOutputPort());vtkNew<vtkActor> cubeActor;cubeActor->SetMapper(cubeMapper);cubeActor->GetProperty()->SetColor(colors->GetColor3d("MistyRose").GetData());// Create a sphere.vtkNew<vtkSphereSource> sphereSource;sphereSource->SetCenter(2, 0, 0);sphereSource->Update();// Create a mapper.vtkNew<vtkPolyDataMapper> sphereMapper;sphereMapper->SetInputConnection(sphereSource->GetOutputPort());// Create an actor.vtkNew<vtkActor> sphereActor;sphereActor->SetMapper(sphereMapper);sphereActor->GetProperty()->SetColor(colors->GetColor3d("LightGoldenrodYellow").GetData());// A renderer and render window.vtkNew<vtkRenderer> renderer;vtkNew<vtkRenderWindow> renderWindow;renderWindow->AddRenderer(renderer);renderWindow->SetWindowName("SelectAnActor");// An interactor.vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;renderWindowInteractor->SetRenderWindow(renderWindow);// Set the custom stype to use for interaction.vtkNew<MouseInteractorStyle5> style;style->SetDefaultRenderer(renderer);style->Cube = cubeActor;style->Sphere = sphereActor;renderWindowInteractor->SetInteractorStyle(style);renderer->AddActor(cubeActor);renderer->AddActor(sphereActor);renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());renderer->ResetCamera();renderer->GetActiveCamera()->Zoom(0.9);// Render and interact.renderWindow->Render();renderWindowInteractor->Initialize();renderWindowInteractor->Start();return EXIT_SUCCESS;
}