QT Opengl Always Giving Black Screen

Question

When i run, it's always giving black screen. I do not understand why. Also there is no error output. Here is the code ,

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QOpenGLWindow>
#include <QSurfaceFormat>
#include <QOpenGLFunctions>
#include <QtOpenGL>
#include <GL/glu.h>

class MainWindow : public QOpenGLWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();


protected:
    virtual void initializeGL();
    virtual void resizeGL(int w, int h);
    virtual void paintGL();
    void resizeEvent(QResizeEvent *event);
    void paintEvent(QPaintEvent *event);

private:
QOpenGLContext *context;
QOpenGLFunctions *openGLFunctions;

};

#endif // MAINWINDOW_H

I've tried lots of other projects and i'm always gettin black screen. I've tried codes from QT documentation, it worked. But in my code, i could'nt do it.

mainwindow.cpp

#include "mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
{
    setSurfaceType(QWindow::OpenGLSurface);

    QSurfaceFormat format;
    format.setProfile(QSurfaceFormat::CompatibilityProfile);
    format.setVersion(2,1);
    setFormat(format);

    context = new QOpenGLContext;
    context->setFormat(format);
    context->create();
    context->makeCurrent(this);

    openGLFunctions = context->functions();
}

MainWindow::~MainWindow()
{

}

void MainWindow::initializeGL()
{

}

void MainWindow::resizeGL(int w, int h)
{

}

void MainWindow::paintGL()
{
    glClearColor(1.0, 0.0f, 0.0f, 0.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    glBegin(GL_QUADS);
    glVertex2f(-0.5f, -0.5f);
    glVertex2f(0.5f, -0.5f);
    glVertex2f(0.5f, 0.5f);
    glVertex2f(-0.5f, 0.5f);

    glEnd();

    glFlush();
}

void MainWindow::resizeEvent(QResizeEvent *event)
{

}

void MainWindow::paintEvent(QPaintEvent *event)
{
    paintGL();
}

What is my problem?

Answer 1

Your implementation is missing initializeGL , renderGl , paintGL functions. You'll have to implement them. Try copying the examples first.