Linking error with mingw (codeblocks)

support
1

I was trying to compile an example code, but couldn’t get past a linking error.

main.cpp(this code is from glfw documentation page):

#include <GLFW/glfw3.h>

int main(void)
{
    GLFWwindow* window;

    /* Initialize the library */
    if (!glfwInit())
        return -1;

    /* Create a windowed mode window and its OpenGL context */
    window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
    if (!window)
    {
        glfwTerminate();
        return -1;
    }

    /* Make the window's context current */
    glfwMakeContextCurrent(window);

    /* Loop until the user closes the window */
    while (!glfwWindowShouldClose(window))
    {
        /* Render here */
        glClear(GL_COLOR_BUFFER_BIT);

        /* Swap front and back buffers */
        glfwSwapBuffers(window);

        /* Poll for and process events */
        glfwPollEvents();
    }

    glfwTerminate();
    return 0;
}

.
.

I am getting two different linker errors:

  1. One is very large(multiple undefined type errors) and occurs when I link libglfw3.a from lib-mingw-w64 folder.

  2. The 2nd error is of single line:
    undefined reference to '__imp_glClear'
    it occurs when I link either:
    libglfw3dll.a FROM lib-mingw-w64 FOLDER or,
    glfw3.dll FROM lib-static-ucrt FOLDER

Removing the line glClear(GL_COLOR_BUFFER_BIT); from the while loop in main.cpp seems to get rid of the 2nd error and successfully compile. And it even gives a simple window when run.
.
.
However, this doesn’t feel right. Deleting a function to stop linker error.
I am new to opengl, glfw and am very clueless about any of the linking stuff so please bear with me. I just can’t figure out, am I forgetting something else to link? Or change some compiler settings maybe?
.
.
Details about the system:
Pre compiled glfw 64 bit windows library
Code blocks (empty project as the template)
msys64 mingw compiler

2

OpenGL functions are not part of glfw. You link to OpenGL library to get them. On Windows GL 1.1 functions are in OpenGL32.dll file.

To link to OpenGL32.dll file add -lopengl32 linker argument - it will make mingw to use libopengl32.a import library.

1 Like
3

Thank you very much. A very silly mistake on my side
edit:
to people using code blocks: add libopengl32.a in the “linker settings”. (assuming the lib folder of your compiler is already included in the search directories of the project)

4

It is worth noting you might need GDI instead (or as well). And the order of linking flags matters in MinGW-w64. So -lglfw3 -lgdi32 works but fails if you swap the flags.

1 Like
5

In my case it worked without linking gdi32