glwidget.h

#ifndef GLWIDGET_H
#define GLWIDGET_H

#include <QCoreApplication>
#include <QOpenGLWidget>
#include <QOpenGLFunctions>
#include <QOpenGLDebugLogger>
#include <QOpenGLVertexArrayObject>
#include <QOpenGLBuffer>
#include <QGLShader>
#include <QOpenGLShaderProgram>
#include <QElapsedTimer>
#include <QTimer>

#include "camera.h"
#include "linevertex.h"

class MainWindow;

class GLWidget : public QOpenGLWidget, protected QOpenGLFunctions
{
    Q_OBJECT

    friend class MainWindow; 

public:
    GLWidget(QWidget *parent, MainWindow *mainWindow);
    ~GLWidget();

    void initLineRenderMode(std::vector<std::vector<LineVertex> > *lines);

    float lineTriangleStripWidth; 
    float lineWidthPercentageBlack; 
    float lineWidthDepthCueingFactor; 
    float lineHaloMaxDepth; 

    bool enableClipping; 
    glm::vec3 clipPlaneNormal; 
    float clipPlaneDistance; 

    inline QImage getImage()
    {
        return this->grabFramebuffer();
    }

    inline void updateClipPlaneNormal()
    {
        clipPlaneNormal = camera.getRight();
    }

    enum RenderMode
    {
        NONE,
        LINES,
        POINTS
    } renderMode;

public slots:
    void cleanup();

signals:
    void usedGPUMemoryChanged(float size);
    void totalGPUMemoryChanged(float size);
    void fpsChanged(int fps);
    void graphicsDeviceInfoChanged(QString string);

protected:

    void mousePressEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
    void mouseMoveEvent(QMouseEvent *event) Q_DECL_OVERRIDE;

    void keyPressEvent(QKeyEvent *event) Q_DECL_OVERRIDE;
    void keyReleaseEvent(QKeyEvent *event) Q_DECL_OVERRIDE;

    void wheelEvent(QWheelEvent *event) Q_DECL_OVERRIDE;

protected slots:

    void paintGL() Q_DECL_OVERRIDE;
    void initializeGL() Q_DECL_OVERRIDE;
    void resizeGL(int w, int h) Q_DECL_OVERRIDE;

private:

    void initShaders();

    void allocateGPUBufferLineData();
    void drawLines();

    void calculateFPS();

    Camera camera;

    std::vector<std::vector<LineVertex> > *lines;
    size_t nrLines;

    // GPU line vertex data and shaders
    // each line vertex has 8 floats: 3 pos, 3 direction to next, 2 uv for triangle strip texturing
    // NOTE: we store two sequential copies of each vertex (one with v = 0, one with v = 1) to draw lines as triangle strips
    QOpenGLShaderProgram *shaderLinesWithHalos;
    QOpenGLVertexArrayObject vaoLines; // VAO remembers states of buffer objects, allowing to easily bind/unbind different buffer states for rendering different objects in a scene.
    QOpenGLBuffer vboLines;

    // GUI ELEMENTS

    QPoint lastMousePos; // last mouse position (to determine mouse movement delta)

    // vars to measure fps
    size_t frameCount = 0;
    size_t fps = 0;
    qint64 previousTimeFPS;
    QElapsedTimer fpsTimer;

    // memory usage
    bool GL_NVX_gpu_memory_info_supported = false;
    GLint total_mem_kb = 0;
    GLint cur_avail_mem_kb = 0;

    // triggers the rendering events
    QTimer paintTimer;

    QOpenGLDebugLogger *logger;
    void printDebugMsg(const QOpenGLDebugMessage &msg) { qDebug() << qPrintable(msg.message()); }

    MainWindow *mainWindow;

};

#endif