OpenGL with Eclipse CDT + MinGW + GLEW + GLFW: Undefined References

Question

Edit: I have in the meantime figured this out and written a detailed answer below.

I just tried switching from the Express version of MSVC 10 to Eclipse CDT on Win7, and while configuring I encountered a problem with the following simple OpenGL code (which works fine in Visual Studio):

#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW/glfw3.h>

int main()
{
    GLFWwindow* w;

    if (!glfwInit())
        return -1;

    w = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
    if (!w)
    {
        glfwTerminate();
        return -1;
    }

    glfwMakeContextCurrent(w);

    glewExperimental = true;
    if (glewInit() != GLEW_OK)
    {
        return -1;
    }

    while (!glfwWindowShouldClose(w))
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glfwSwapBuffers(w);
        glfwPollEvents();
    }

    glfwTerminate();
    return 0;
}

In Visual Studio, I include the library paths for GLFW and GLEW, and link (in addition to the stuff that VS does built-in) opengl32.lib, glew32s.lib, glfw3.lib, in that order.

Now if I do the same in Eclipse CDT, I can't get it to work. The following errors occur:

Info: Internal Builder is used for build
g++ "-LD:\\lib\\cpp\\glfw-3.0.1.bin.WIN32\\lib-mingw" "-LD:\\lib\\cpp\\glew-1.10.0binaries\\lib\\Release\\Win32" -o glfwcheck.exe main.o -lopengl32 -lglew32s -lglfw3 
Warning: .drectve `/DEFAULTLIB:"LIBCMT" /DEFAULTLIB:"OLDNAMES" ' unrecognized
D:\lib\cpp\glew-1.10.0binaries\lib\Release\Win32/glew32s.lib(tmp/glew_static/Release/Win32/glew.obj):(.text[__glewInit_GL_VERSION_1_2]+0x4): undefined reference to `_imp__wglGetProcAddress@4'
D:\lib\cpp\glew-1.10.0binaries\lib\Release\Win32/glew32s.lib(tmp/glew_static/Release/Win32/glew.obj):(.text[__glewInit_GL_VERSION_1_3]+0x4): undefined reference to `_imp__wglGetProcAddress@4'
d:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: D:\lib\cpp\glew-1.10.0binaries\lib\Release\Win32/glew32s.lib(tmp/glew_static/Release/Win32/glew.obj): bad reloc address 0x4 in section `.text[__glewInit_GL_VERSION_1_3]'
d:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: final link failed: Invalid operation
collect2.exe: error: ld returned 1 exit status

Of course I tried changing the order of the three libraries, but that only mad it worse. (By the way: I think it's strange that I can't reproduce these errors above such that they're the only ones when I re-arrange the libs to the initial order. I stay at 20+ errors until I delete ALL the libs, build, and add them again.)

After fumbling around and looking through forum posts, I figured that maybe it's a problem with the GLEW binaries, and compiled them on my own with MinGW. Only this time, I get all the 'not found' errors. I don't know how I can link statically with my self-compiled GLEW, since there's now no glew32s.lib any longer, but only libglew32.a and libglew32mx.a. Linking dynamically with glew32 and putting the dll into my project folder didn't work either.

I feel like I'm doing something very wrong here in Eclipse, or just forget some additional libraries (although I once tried putting all the ones VS uses in there as well and it still did the exact same thing).

Can you help me out? :) Otherwise I think I'd have to stay with VS, or switch to Linux + make.

Excaudate

This is doesn't solve the problem, but it will solve a future problem. You need to call glewInit() after you call glfwMakeContextCurrent(w); – Orchestrion

@Vallentin Thanks, and you're right, I think I even encountered this once when switching to GLFW3 :D – Excaudate

@Excaudate - you are doing great work with suggested edits on the questions, so much so that I thought I should somehow let you know (even though this is not the place!). Keep up the good work! – Decrement

Answer 1

I figured it out, and for anyone ever encountering the issue I will try and make clear what exactly I did to finally be able to create OpenGL projects with the setup MinGW + GLEW + GLFW. In my case, I used Eclipse CDT as IDE, but I'll write down the resulting g++ command line so it should be easy to adapt to other IDE's.

1. I'll suppose MinGW and MSYS (can be chosen to be installed from within the MinGW GUI; thus no need to download separately) are installed.

2. Download GLFW and unzip it in your external libraries folder of choice (in my case, this is D:\external\cpp, so it would be something along the lines of D:\external\cpp\glfw, where I renamed the glfw-3.0.3.bin.WIN32 folder to simply glfw).

3. Download the GLEW source as a zip folder an unzip it, in my case it's in D:\external\cpp\glew. Now start MSYS, cd to the glew folder and invoke make all.

4. Step 3 should have created (among others) the files libglew32.a and glew32.dll inside the folder glew\lib. Now right click your Eclipse CDT C++ project, go to Properties - C/C++ General - Paths and Symbols. In the Includes tab, add the paths to the include folders of GLFW and GLEW. Again, for me this is D:\external\cpp\glew\include and analogous for GLFW. In Library Paths, do the same for the folders lib (GLEW) and lib-mingw (GLFW).

5. Now we have to add the libraries we want our project to be linked with. If you wish to link with GLEW dynamically, make sure to include the glew32.dll in the folder where your executable will be. In Eclipse CDT, that's usually the Debug (or Release) folder in your project structure. In the Libraries tab in the options window we opened before, add (the order is important!) glfw3, glew32, opengl32, glu32, gdi32. Now building the project should work hopefully. In case you want to link statically with GLEW, add the same libraries with the exception of glew32. Instead, in the project properties go to C/C++ Build - Settings and in the Tool Settings - MinGW C++ Linker - Miscellaneous tab add the path to libglew32.a to the Other objects field. In my case, this is D:\external\cpp\glew\lib\libglew32.a. Now in order for the static linking to work, you have to either add #define GLEW_STATIC above #include <GL/glew.h> or use the preprocessor command -DGLEW_STATIC. The GLEW homepage says that it's also possible to include the glew.c and glew.h files into your project in order to link statically, but somehow this didn't really work out for me.

These steps worked for me, and they produced command lines similar to the following (I have only one file named main.cpp and used static linking with GLEW), which could be useful if you're trying to figure this matter out without Eclipse CDT.

g++ -ID:\external\cpp\glew\include -ID:\external\cpp\glfw\include -c -o main.o main.cpp
g++ -LD:\external\cpp\glew\lib -LD:\external\cpp\glfw\lib-mingw -o minimalexample.exe main.o D:\external\cpp\glew\lib\libglew32.a -lglfw3 -lopengl32 -lglu32 -lgdi32

In the dynamic linking case, simply remove the part containing libglew32.a in the second line, and add -lglew32 between -lglfw3 and -lopengl32. As a little example source file, you could just use the code in my above question.

I hope I can help anyone with this, as I sure saw me having a lot of trouble figuring this out between tens of error messages of unresolved symbols and various other problems :-)

Update: I tried to go over this again some days ago and ran into problems with the pre-compiled GLFW binaries for Windows (I'm now using Win8.1). But you can just use CMake in combination with mingw32-make to compile it on your own. Also, GLEW seems to not be getting updates anymore, so I switched to glad instead. It's also possible to use MinGW-w64 to compile the libraries and your final project as 64-bit application.

Excaudate

On step 3 I was stuck on how to navigate to the glew folder in msys. The answers to this quesiton helped me: https://mcmap.net/q/158782/-how-do-i-navigate-my-windows-folders-like-c-drive-in-msys – Loiseloiter