qglviewer.h

#ifndef QGLVIEWER_H
#define QGLVIEWER_H

#include <QOpenGLWidget>
#include <QOpenGLFunctions>
#include <QOpenGLVertexArrayObject>
#include <QOpenGLBuffer>

#include <QMatrix4x4>

#include "gldata.h"

QT_FORWARD_DECLARE_CLASS(QOpenGLShaderProgram)
QT_FORWARD_DECLARE_CLASS(Camera)


struct GridConfig {
  GridConfig();

  int minX, maxX;   // draw the grid from minX to maxX
  int minY, maxY;   // ...and from minY to maxY
  int step;

  QVector3D color;  // grid color
};

struct AxesConfig {
  AxesConfig();

  float length;
  float arrowSize;

  QVector3D colorX, colorY, colorZ;
};


class QGLViewer : public QOpenGLWidget, protected QOpenGLFunctions
{
  Q_OBJECT
public:
  QGLViewer(QWidget *parent = nullptr);
  ~QGLViewer() override;

  QSize minimumSizeHint() const override;
  QSize sizeHint() const override;

  Camera *camera() const { return m_camera; }

  void setData(const GLData &data);

  void setGridConfig(const GridConfig &grid);
  void setAxesConfig(const AxesConfig &axes);

protected:
  void initializeGL() override;
  void paintGL() override;
  void resizeGL(int width, int height) override;
  void keyPressEvent(QKeyEvent *event) override;
  void mousePressEvent(QMouseEvent *event) override;
  void mouseMoveEvent(QMouseEvent *event) override;
  void wheelEvent(QWheelEvent *event) override;

private:
  void initializeGridAndAxes();
  void setupGL();
  void setupVertexAttribs();

  QPoint m_lastPos;

  GLData m_data;

  // draw as triangles
  QOpenGLVertexArrayObject m_trisVao;
  QOpenGLBuffer m_trisVbo;

  // draw as lines: grid and axes
  QOpenGLVertexArrayObject m_linesVao;
  QOpenGLBuffer m_linesVbo;

  bool m_drawGrid;
  int m_gridVertexIdx;
  GridConfig m_gridConfig;

  bool m_drawAxes;
  int m_axesVertexIdx;
  AxesConfig m_axesConfig;

  QOpenGLShaderProgram *m_program;

  Camera *m_camera;

  int m_mvpMatrixLoc;
};

#endif