Need help; QPushButton to control OpenGL

[doughng]

Hi,
I'm absolutely new to programming, but I've been reading about OpenGL/Qt, and I learnt to render an OpenGL object using QGLWidget. Now I'm trying to create a GUI in which OpenGL objects are only rendered whenever QPushButton is clicked. I read about slot/signal, but I still dont understand where to place my functions, and how to implement it. Please I need help!

[andre]

Did you try to do some of the basic tutorials on Qt programming?

[doughng]

The ones I found were direct examples of slots/signals...nothing to do with OpenGL. I would appreciate any good ones that relate or has the same idea as what I want to achieve

[sierdzio]

You just implement your OpenGL code in the slot's body. Then connect QPushButton's clicked() signal to your new slot. I think it was you who sent me a PM about it? I've linked some handy docs there.

[doughng]

yeah, its me :)

[sierdzio]

I find the best way to learn programming is to try - you'll learn as soon as you get it to work yourself. This way, it's your thinking that analyses the problem, finds a solution, and then finds a way to implement that solution in a given programming language.

[doughng]

I'm on it, thanks very much

[doughng]

I worked on a basic GLUT model in Qt, and it shows a white screen and crashes, I need help.

The program has unexpectedly finished.
C:\QtGL\myGL-build-desktop-Qt_4_7_4_for_Desktop-MinGW_4_4__Qt_SDK__Debug\debug\myGL.exe exited with code -1073741819

Here're my codes:

GLWidget.cpp
@#include "glwidget.h"
#include<GL/glut.h>

GLWidget::GLWidget(QWidget *parent) :
QGLWidget(parent)
{
}
void GLWidget::initializeGL()
{
glClearColor(0.0, 0.0, 0.0, 0); // Background Color

}

void GLWidget::resizeGL(int width, int height)
{
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0, (float)width / (float)height, 0.1, 1000.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(
0.0, 0.0, 200.0, // eye location
0.0, 0.0, 0.0, // center location
0.0, 1.0, 0.0); // up vector
}

void GLWidget::drawGL(){
glColor3f(1.0f, 0.0f, 0.0f); //set cube color
glutWireTeapot(30); //use the premade glut function to draw a wire cube of size 30
glutSwapBuffers();
}

void GLWidget::paintGL()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
drawGL();

}
@

GLWidget.h
@#ifndef GLWIDGET_H
#define GLWIDGET_H

#include <QGLWidget>

class GLWidget : public QGLWidget
{
Q_OBJECT

public:
explicit GLWidget(QWidget *parent = 0);

protected:
void initializeGL();
void resizeGL(int width, int height);
void paintGL();

private:
void drawGL();

signals:

public slots:

};

#endif // GLWIDGET_H
@

Mainwidget.h
@#ifndef MAINWIDGET_H
#define MAINWIDGET_H

#include <QWidget>

namespace Ui {
class MainWidget;
}

class MainWidget : public QWidget
{
Q_OBJECT

public:
explicit MainWidget(QWidget *parent = 0);
~MainWidget();

private:
Ui::MainWidget *ui;
};

#endif // MAINWIDGET_H
@

Main.cpp
@#include <QtGui/QApplication>
#include <GL/glut.h>
#include "mainwidget.h"

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWidget w;
w.show();

return a.exec();

}
@

Mainwidget.cpp
@#include "mainwidget.h"
#include "ui_mainwidget.h"

MainWidget::MainWidget(QWidget *parent) :
QWidget(parent),
ui(new Ui::MainWidget)
{
ui->setupUi(this);
}

MainWidget::~MainWidget()
{
delete ui;
}
@

[doughng]

I found the problem, I'm using a single buffer, not double buffer. I commented glutSwapBuffers() out and it works fine.