【VTK】基于读取出来的 STL 模型，当用户点击鼠标左键时，程序将获取点击位置的点，显示其坐标，并设置它为模型的旋转原点

知识不是单独的，一定是成体系的。更多我的个人总结和相关经验可查阅这个专栏：Visual Studio。

基于读取出来的 STL 模型，实现当用户点击鼠标左键时，程序将获取点击位置的点，显示其坐标，并设置它为模型的旋转原点。

详细流程为：点击 Select 按钮，鼠标具备选择的功能。当按下 Select Done 鼠标删除掉此功能。

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主要是通过两个类和一个函数来实现的：

• class PointPickedSignal : public QObject
• class MouseInteractorCommand : public vtkCommand
• void A::on_pushButtonSelected_clicked()
• void A::onPointPicked(double* pos)

下边依次分析。

class PointPickedSignal : public QObject

class PointPickedSignal : public QObject
{
    Q_OBJECT
public:
    PointPickedSignal(QObject* parent = nullptr) : QObject(parent) {}

signals:
    void pointPicked(double* pos);
};

这个类继承自 QObject 类，用于实现一个名为 pointPicked 的 Qt 信号，当一个点被选中时发出该信号。这个信号将被用于通知其他对象选中的点的坐标。

class MouseInteractorCommand : public vtkCommand

class MouseInteractorCommand : public vtkCommand
{
public:
    vtkTypeMacro(MouseInteractorCommand, vtkCommand);

    static MouseInteractorCommand* New()
    {
        return new MouseInteractorCommand;
    }

    virtual void Execute(vtkObject* caller, unsigned long eventId, void* vtkNotUsed(callData))
    {
        vtkRenderWindowInteractor* interactor = vtkRenderWindowInteractor::SafeDownCast(caller);
        int* clickPos = interactor->GetEventPosition();

        vtkSmartPointer<vtkCellPicker> picker = vtkSmartPointer<vtkCellPicker>::New();
        picker->SetTolerance(0.0005);

        if (picker->Pick(clickPos[0], clickPos[1], 0, interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer()))
        {
            double* pos = picker->GetPickPosition();
            memcpy(pickedPoint, pos, sizeof(double) * 3);
            emit signal->pointPicked(pickedPoint);
        }
    }

    double pickedPoint[3];
    PointPickedSignal* signal; // this will emit the pointPicked signal when a point is picked
};

这个类继承自 vtkCommand 类，其功能是监听鼠标左键的点击事件。当用户点击鼠标左键时，会触发 Execute 方法。在这个方法中，代码首先从事件的发起者中获取交互器，并从交互器中获取点击的位置。然后，它创建一个 vtkCellPicker 对象并尝试拾取点击位置的点。如果成功拾取了一个点，它将获取该点的坐标，并使用 memcpy 将这些坐标复制到 pickedPoint 数组中。最后，它发出 pointPicked 信号，将选中的点的坐标作为参数。

void A::on_pushButtonSelected_clicked()

void A::on_pushButtonSelected_clicked() {
    ui.textBrowser->insertPlainText("Button Clicked");

    PointPickedSignal* signal = new PointPickedSignal(this);
    
    vtkSmartPointer<MouseInteractorCommand> command = vtkSmartPointer<MouseInteractorCommand>::New();
    command->signal = signal;
    
    ui.qvtkWidget->interactor()->AddObserver(vtkCommand::LeftButtonPressEvent, command);

    QEventLoop loop;
    connect(signal, &PointPickedSignal::pointPicked, this, &A::onPointPicked);
    connect(signal, &PointPickedSignal::pointPicked, &loop, &QEventLoop::quit);
    loop.exec();

    onPointPicked(command->pickedPoint);
}

这个方法首先创建一个 PointPickedSignal 对象和一个 MouseInteractorCommand 对象。然后，它将 PointPickedSignal 对象赋值给 MouseInteractorCommand 对象的 signal 成员，然后将这个 MouseInteractorCommand 对象添加为 QVTKWidget 对象的交互器的观察者，这样当交互器收到左键按下事件时，就会执行 MouseInteractorCommand 对象的 Execute 方法。

然后，这个方法创建一个 QEventLoop 对象并开始执行事件循环。在事件循环中，当 pointPicked 信号被发出时，它将调用 A::onPointPicked() 方法，并结束事件循环。

void A::onPointPicked(double* pos)

void A::onPointPicked(double* pos) {
    ui.textBrowser->insertPlainText(QString("Point picked: %1 %2 %3\n").arg(pos[0]).arg(pos[1]).arg(pos[2]));
    ui.textBrowser->moveCursor(QTextCursor::End);
    mandibleActor->SetOrigin(pos);
}

当这个方法被调用时，它将在文本浏览器中显示选中的点的坐标，并将这个点设置为模型的旋转原点。

通过这种方式，当用户点击鼠标左键时，程序将获取点击位置的点，显示其坐标，并设置它为模型的旋转原点。

---

完整版代码如下：

A.h

// A.h
#pragma once

#include 
#include "ui_A.h"

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#include 
#include 
#include 
#include 
#include 
#include 
#include 

#include 

class A : public QMainWindow
{
    Q_OBJECT

public:
    A(QWidget* parent = nullptr);
    ~A();

private slots:
    void on_pushButtonSelect_clicked();
    void on_pushButtonSelDone_clicked();
    void onPointPicked(double* pos);

    void rotate();

private:
    Ui::AClass ui;

    void initVTK();

    vtkSmartPointer<vtkActor> actor;
    vtkSmartPointer<vtkRenderer> renderer;
    vtkSmartPointer<vtkGenericOpenGLRenderWindow> renderWindow;

    QTimer* timer;
};

class PointPickedSignal : public QObject
{
    Q_OBJECT
public:
    PointPickedSignal(QObject* parent = nullptr) : QObject(parent) {}

signals:
    void pointPicked(double* pos);
};

class MouseInteractorCommand : public vtkCommand
{
public:
    vtkTypeMacro(MouseInteractorCommand, vtkCommand);

    static MouseInteractorCommand* New()
    {
        return new MouseInteractorCommand;
    }

    virtual void Execute(vtkObject* caller, unsigned long eventId, void* vtkNotUsed(callData))
    {
        vtkRenderWindowInteractor* interactor = vtkRenderWindowInteractor::SafeDownCast(caller);
        int* clickPos = interactor->GetEventPosition();

        vtkSmartPointer<vtkCellPicker> picker = vtkSmartPointer<vtkCellPicker>::New();
        picker->SetTolerance(0.0005);

        if (picker->Pick(clickPos[0], clickPos[1], 0, interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer()))
        {
            double* pos = picker->GetPickPosition();
            memcpy(pickedPoint, pos, sizeof(double) * 3);
            emit signal->pointPicked(pickedPoint);
        }
    }

    double pickedPoint[3];
    PointPickedSignal* signal; // this will emit the pointPicked signal when a point is picked
};

A.cpp

// A.cpp
#include "A.h"



A::A(QWidget* parent)
    : QMainWindow(parent)
{
    ui.setupUi(this);

    // 配置 VTK 的初始设置
    initVTK();

    // 定时器，50ms 更新触发一次 checkPositionChange()
    timer = new QTimer(this);
    connect(timer, SIGNAL(timeout()), this, SLOT(rotate()));
    timer->start(100);
}

A::~A()
{
}

void A::initVTK()
{
    // 读取 STL 文件
    vtkSmartPointer<vtkSTLReader> reader = vtkSmartPointer<vtkSTLReader>::New();
    reader->SetFileName("skull_50.stl"); // 请替换为你的 STL 文件路径
    reader->Update();

    // 创建映射器和演员
    vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
    mapper->SetInputConnection(reader->GetOutputPort());

    actor = vtkSmartPointer<vtkActor>::New();
    actor->SetMapper(mapper);

    // 创建渲染器
    renderer = vtkSmartPointer<vtkRenderer>::New();
    // 添加演员到渲染器
    renderer->AddActor(actor);

    // 创建渲染窗口和渲染窗口交互器
    renderWindow = vtkSmartPointer<vtkGenericOpenGLRenderWindow>::New();
    renderWindow->AddRenderer(renderer);

    // 添加到 qvtkWidget 控件中显示
    ui.qvtkWidget->setRenderWindow(renderWindow);

}

void A::on_pushButtonSelect_clicked() {
    ui.textBrowser->insertPlainText("Select button clicked!\n");

    PointPickedSignal* signal = new PointPickedSignal(this);
    vtkSmartPointer<MouseInteractorCommand> command = vtkSmartPointer<MouseInteractorCommand>::New();
    command->signal = signal;
    ui.qvtkWidget->interactor()->AddObserver(vtkCommand::LeftButtonPressEvent, command);

    QEventLoop loop;
    connect(signal, &PointPickedSignal::pointPicked, this, &A::onPointPicked);
    connect(signal, &PointPickedSignal::pointPicked, &loop, &QEventLoop::quit);
    loop.exec();

    onPointPicked(command->pickedPoint);
}

void A::onPointPicked(double* pos) {
    ui.textBrowser->insertPlainText(QString("Point picked: %1 %2 %3\n").arg(pos[0]).arg(pos[1]).arg(pos[2]));
    ui.textBrowser->moveCursor(QTextCursor::End);
    actor->SetOrigin(pos);
}

void A::on_pushButtonSelDone_clicked() {
    ui.textBrowser->insertPlainText("Selection done, restore the default interactor style.\n");

    // 移除左键按下事件的观察者
    ui.qvtkWidget->interactor()->RemoveObservers(vtkCommand::LeftButtonPressEvent);

    // 恢复默认的交互器样式。
    vtkSmartPointer<vtkInteractorStyleTrackballCamera> style = vtkSmartPointer<vtkInteractorStyleTrackballCamera>::New();
    ui.qvtkWidget->interactor()->SetInteractorStyle(style);
}

void A::rotate()
{
    actor->RotateX(5);
    renderWindow->Render();
}

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Ref.

1. 骷髅3D打印3D模型