Can't compile simple source code working with OpenGL

[Zholaman]

Hi, please help.

I can't compile simple source code working with OpenGL, taking from "Qt 5.3 Professional programming with C++" book (author Max Schlee).

Every time when I build the source code I get the following errors:

• D:\c++_project\build-OGLQuad-Desktop_Qt_5_5_1_MinGW_32bit-Debug\debug\OGLQuad.o:-1: In function `ZN7OGLQuad8resizeGLEii':
• D:\c++_project\test9\OGLQuad.cpp:37: error: undefined reference to `_imp__glMatrixMode@4'
• D:\c++_project\test9\OGLQuad.cpp:38: error: undefined reference to `_imp__glLoadIdentity@0'
• D:\c++_project\test9\OGLQuad.cpp:39: error: undefined reference to `_imp__glViewport@16'
• D:\c++_project\test9\OGLQuad.cpp:40: error: undefined reference to `_imp__glOrtho@48'
• D:\c++_project\test9\OGLQuad.cpp:46: error: undefined reference to `_imp__glClear@4'
• D:\c++_project\test9\OGLQuad.cpp:48: error: undefined reference to `_imp__glBegin@4']([link url]([link url](link url)))
  etc

I use Qt 5.5.1, Qt Creator 3.6, MinGW 4.9.3 (32bit)

My environment:
OS Windows 7, 64bit.

Source code of my project:

pro file.

TEMPLATE = app
QT += widgets opengl core gui
HEADERS = OGLQuad.h
SOURCES = OGLQuad.cpp
main.cpp
windows:TARGET = ../OGLQuad

main.cpp

#include <QApplication>
#include "OGLQuad.h"

// ----------------------------------------------------------------------
int main(int argc, char** argv)
{
    QApplication app(argc, argv);
    OGLQuad      oglQuad;

    oglQuad.resize(200, 200);
    oglQuad.show();

    return app.exec();
}

---

OGLQuad.h

#pragma once

#include <QGLWidget>

class OGLQuad : public QGLWidget {
protected:
    virtual void initializeGL(                       );
    virtual void resizeGL    (int nWidth, int nHeight);
    virtual void paintGL     (                       );

public:
    OGLQuad(QWidget* pwgt = 0);
};

---

OGLQuad.cpp

#include "OGLQuad.h"

// ----------------------------------------------------------------------
OGLQuad::OGLQuad(QWidget* pwgt/*= 0*/) : QGLWidget(pwgt) 
{
}

// ----------------------------------------------------------------------
/*virtual*/void OGLQuad::initializeGL()
{
    qglClearColor(Qt::black);
}

// ----------------------------------------------------------------------
/*virtual*/void OGLQuad::resizeGL(int nWidth, int nHeight)
{
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glViewport(0, 0, (GLint)nWidth, (GLint)nHeight);
    glOrtho(0, 100, 100, 0, -1, 1); 
}

// ----------------------------------------------------------------------
/*virtual*/void OGLQuad::paintGL()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glBegin(GL_QUADS);
        glColor3f(1, 0, 0); 
        glVertex2f(0, 100);

        glColor3f(0, 1, 0);
        glVertex2f(100, 100);

        glColor3f(0, 0, 1);
        glVertex2f(100, 0);

        glColor3f(1, 1, 1);
        glVertex2f(0, 0);
    glEnd();
}

---

Thanks

[Zholaman]

@Zholaman For those who faced with this problem.

I have resolved it by adding the following lib in my pro file:

LIBS += -LD:\Qt\5.5\mingw492_32\lib\libQt5OpenGL.a -lopengl32

The D:\Qt\5.5\mingw492_32\lib\libQt5OpenGL.a is path to lib file (libQt5OpenGL.a)