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#ifndef GLWIDGET_H
#define GLWIDGET_H

#include <QOpenGLWidget>
#include <QOpenGLFunctions>
#include <QOpenGLShaderProgram>
#include <QOpenGLBuffer>
#include <QVector3D>
#include <QMatrix4x4>
#include <QThread>
#include <QMutex>
#include <QWaitCondition>
#include <QElapsedTimer>

class GLWidget;

class Renderer : public QObject, protected QOpenGLFunctions
{
    Q_OBJECT

public:
    Renderer(GLWidget *w);
    void lockRenderer() { m_renderMutex.lock(); }
    void unlockRenderer() { m_renderMutex.unlock(); }
    QMutex *grabMutex() { return &m_grabMutex; }
    QWaitCondition *grabCond() { return &m_grabCond; }
    void prepareExit() { m_exiting = true; m_grabCond.wakeAll(); }

signals:
    void contextWanted();

public slots:
    void render();

private:
    void paintQtLogo();
    void createGeometry();
    void quad(qreal x1, qreal y1, qreal x2, qreal y2, qreal x3, qreal y3, qreal x4, qreal y4);
    void extrude(qreal x1, qreal y1, qreal x2, qreal y2);

    bool m_inited = false;
    qreal m_fAngle = 0;
    qreal m_fScale = 1;
    QList<QVector3D> vertices;
    QList<QVector3D> normals;
    QOpenGLShaderProgram program;
    QOpenGLBuffer vbo;
    int vertexAttr = 0;
    int normalAttr = 0;
    int matrixUniform = 0;
    GLWidget *m_glwidget = nullptr;
    QMutex m_renderMutex;
    QElapsedTimer m_elapsed;
    QMutex m_grabMutex;
    QWaitCondition m_grabCond;
    bool m_exiting = false;
};

class GLWidget : public QOpenGLWidget
{
    Q_OBJECT
public:
    explicit GLWidget(QWidget *parent = nullptr);
    ~GLWidget();

protected:
    void paintEvent(QPaintEvent *) override { }

signals:
    void renderRequested();

public slots:
    void grabContext();

private slots:
    void onAboutToCompose();
    void onFrameSwapped();
    void onAboutToResize();
    void onResized();

private:
    QThread *m_thread;
    Renderer *m_renderer;
};

#endif
