Opengl doesn't work with Qt



  • Hi Guys, I am using windows 7 and trying to writing my c++ codes in Qt using opengl, but always I have problem which can not open opengl library like glut or glut32, I search a lot but no correct answer, please help me ...



  • Maybe you can provide more info? Errors, sample code, etc.?

    P.S. And it is Qt, not QT :) Please change title



  • Hi Thanks for P.S ;) .... it's a very simple code to draw a line just for test, but the error happens when it wants to be complied, the error is about opengl calling function like "glutDisplayFunc(display)" or "glutInit(&argc, argv)" which can not refer to them, I check .pro file in Qt and the command Qt+= opengl is exist, so I guess there should be an other problem.....



  • Can you post here exact error? I doubt that I will help (never tried opengl under windows), but it will be easier for others to help with all info you can give.



  • You need to link to glut too since this is not part of the core OpenGL but rather an add-on utility library. Just add

    @
    LIBS += -lglut
    @

    to your project's .pro file, re-run qmake and build.



  • Hi Guys sorry for my late reply, here is errors :

    C:\Users\FGHASSEMIT\ne1\ne1.cpp:-1: error: undefined reference to __glutInitWithExit@12' C:\Users\FGHASSEMIT\ne1\ne1.cpp:-1: error: undefined reference toglutInitDisplayMode@4'
    C:\Users\FGHASSEMIT\ne1\ne1.cpp:-1: error: undefined reference to glutInitWindowSize@8' C:\Users\FGHASSEMIT\ne1\ne1.cpp:-1: error: undefined reference toglutInitWindowPosition@8'
    C:\Users\FGHASSEMIT\ne1\ne1.cpp:-1: error: undefined reference to __glutCreateWindowWithExit@8' C:\Users\FGHASSEMIT\ne1\ne1.cpp:-1: error: undefined reference toglutDisplayFunc@4'
    C:\Users\FGHASSEMIT\ne1\ne1.cpp:-1: error: undefined reference to `glutMainLoop@0'
    :-1: error: collect2: ld returned 1 exit status

    and here is my .pro file :

    TARGET = ne1

    TEMPLATE = app

    DEPENDPATH += .

    INCLUDEPATH += .

    SOURCES += ne1.cpp

    HEADERS += ne1.h
    ne1_global.h

    CONFIG += opengl
    release

    QT += opengl

    LIBS += -glut32 -glut


    for "LIBS += " I changed for only -glut but still the same errors come ...
    Looking forward for your solution
    Thanks in advance .



  • @
    LIBS += -lglut
    @

    notice the -l. The following .pro file works for me with a simple OpenGL example that uses glut:

    @
    QT += opengl

    TARGET = 06-solar-system
    TEMPLATE = app

    SOURCES += main.cpp
    solarsystem.cpp

    HEADERS += solarsystem.h

    LIBS += -lglut
    @



  • I guess you work with linux, I used this command as well then I have error that says can not find lglut, one of my colleague work with linux and uses LIBS += -lglut and he can work but for me it doenst work since I am using windows 7 ....
    :(



  • True. I'll try it on windows tonight.



  • oh many many thanks ... I am eagerly looking forward to hear good news from you ...... :)



  • If you really want ot use GLUT, I think you'll have to find a Windows port of GLUT, and install it, e.g. "this one":http://www.xmission.com/~nate/glut.html. Then, you must add the library, as well as the path to where you installed it, to the LIBS variable. And possible set the include path as well.

    But, most of the things you get from using GLUT are things you don't really need when you use OpenGL with Qt. It makes sense to use GLUT or Qt, but not really both.



  • Is it something different with the glut which I am currently using in c++ under the same windows ??? because in c++ I have no problem with openGl and all its library only in Qt ...



  • You are saying that you can use GLUT from plain C++ code, but not from Qt code? In that case you must have it installed somewhere already. You just need to tell where, in your .pro file, so that qmake can find it. I.e., you must add something like:
    @
    LIBS += -lglut
    LIBS += -LC:/location/of/glut
    @
    I'm not sure this is what's missing, though. Since you don't get an error saying it cannot find the glut library. Looks like it actually finds it, but not the symbols it needs. Strange.

    Which compiler are you using? The same one you use when compiling plain C++ code?



  • Yes I am using in plain C++ without problem,
    But I can not find any file like lglut in my pc(where can I get this file) ??????
    I have only glut, glut32 (header file and lib file )....
    but I never tried the second line which you mentioned above, I will try the second one seems by the second line error should be gone hopefully by the way now I uninstall the Qt and trying to get the new version as soon as I install I will apply this and I will let you know about it .... many many thanks to you that spend your time for my problem .....



  • -l stands for library and -L for library path, see "qmake doc":http://doc.qt.nokia.com/4.7/qmake-variable-reference.html#libs
    [quote author="fery13" date="1309197219"]Yes I am using in plain C++ without problem,
    But I can not find any file like lglut in my pc(where can I get this file) ??????
    I have only glut, glut32 (header file and lib file ).... [/quote]



  • -lglut is like a command line option, which you use to tell qmake to use a library. -l is the option and glut the argument. On Windows, the file should be called glut.lib. -L is used to add a directory in which to look for libraries.

    I don't think this is the problem, though. It seems to find GLUT and is unable to link with it. Maybe you simply cannot do this, because using those functions mentioned above together with Qt really makes no sense.



  • Try @LIBS += -L/path/to/your/lib -lLibfile_without_exstension@



  • Just had a look in my OpenGL installation, which is the one that comes with mingw / Qt Creator, and it contains glu, but not glut. So your glut must come from somewhere else.



  • That's strange I tried all, but still errors, also I re install Qt ... here is my .pro:
    @
    #-------------------------------------------------

    Project created by QtCreator 2011-06-23T18:42:17

    #-------------------------------------------------

    TARGET = open1

    TEMPLATE = app

    DEPENDPATH += .

    INCLUDEPATH += .

    SOURCES += open1.cpp

    HEADERS += open1.h
    open1_global.h

    CONFIG += opengl
    release

    QT += opengl

    LIBS += -lglut
    LIBS += C:\Users\FGHASSEMIT\Documents\qt\GL\glut.lib
    @
    and here errors :

    :-1: error: cannot find -lglut
    :-1: error: collect2: ld returned 1 exit status

    .................
    this is the same if I write glut32 instead of glut ....
    :(

    Edit: Added @ tags



  • Try also adding:

    @
    LIBS += -LC:/path/to/your/glut/lib
    @



  • I did then I have again error :

    :-1: error: LC:/Users/FGHASSEMIT/Documents/qt/GL/glut.lib: Invalid argument

    I guess LC is used for Linux ....



  • You are now trying to link with glut twice... Your .pro file should contain
    @
    LIBS += -lglut
    LIBS += -LC:\Users\FGHASSEMIT\Documents\qt\GL
    @
    or just
    @
    LIBS += C:\Users\FGHASSEMIT\Documents\qt\GL\glut.lib
    @
    but not both.

    Nevertheless, I think you should try to get rid of the glut dependency, because using it with Qt will most likely create problems.



  • sorry I forget to put dash (-) behind so the errors turn to be like this :

    C:\Users\FGHASSEMIT\open1\open1.cpp:-1: error: undefined reference to __glutInitWithExit' C:\Users\FGHASSEMIT\open1\open1.cpp:-1: error: undefined reference toglutInitDisplayMode'
    C:\Users\FGHASSEMIT\open1\open1.cpp:-1: error: undefined reference to glutInitWindowSize' . . . C:\Users\FGHASSEMIT\open1\open1.cpp:-1: error: undefined reference to_imp__glBegin'
    C:\Users\FGHASSEMIT\open1\open1.cpp:-1: error: undefined reference to _imp__glVertex2f' C:\Users\FGHASSEMIT\open1\open1.cpp:-1: error: undefined reference to_imp__glEnd'
    C:\Users\FGHASSEMIT\open1\open1.cpp:-1: error: undefined reference to `_imp__glFlush'
    :-1: error: collect2: ld returned 1 exit status



  • I agree with ludde. You are trying to use glut to reproduce functionality that is already in Qt. Some glut functions can still make sense to use within Qt (ie for drawing basic geometric shapes such as a sphere).

    Take a look at my repository to see a few very simple OpenGL apps that use Qt rather than glut for the windowing functionality. Just use svn to checkout:

    @
    https://svn.theharmers.co.uk/svn/codes/public/opengl/trunk/
    @

    cd into one of the directories e.g. 06-solar-system then run:

    @
    qmake
    make
    @


Log in to reply
 

Looks like your connection to Qt Forum was lost, please wait while we try to reconnect.