GL/GLFW Example Displays GLAD Version "0.1"

[zaruhev]

GL/GLFW Example Displays GLAD Version "0.1"

[Dav1dde]

Mh that should work, can you debug into glad_gl_find_core_gl either via a debugger or just add a few printf's, I am mainly interested in the version string before the GLAD_IMPL_UTIL_SSCANF call and the major, minor variables after.

[Dav1dde]

What does glGetString(GL_VERSION) return?

[zaruhev]

Hello Dav1dde, thank you for responding so quickly.

glGetString(GL_VERSION) returns "4.6.0 Core Profile Context 24.1.1.231127", I think as expected.

[zaruhev]

Thank you for the advice. I was able to find the source of the problem. As it turns out, glad_gl_find_core_gl and GLAD_IMPL_UTIL_SSCANF are not called at any point.

It seems that GLAD_GL_IMPLEMENTATION must be defined before gl.h is included in order to be called, so I assume the version is not set otherwise. After adding #define GLAD_GL_IMPLEMENTATION before #include <glad/gl.h>, the version is properly set:

Should I fork and PR the example with the definition of GLAD_GL_IMPLEMENTATION?

Revised source file:

#include <stdlib.h>
#include <stdio.h>

#define GLAD_GL_IMPLEMENTATION
#include <glad/gl.h>

#include <GLFW/glfw3.h>


const GLuint WIDTH = 800, HEIGHT = 600;

void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode) {
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(window, GL_TRUE);
}

int main(void) {
    glfwInit();

    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4); // GL version edited for version test
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 6);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "[glad] GL with GLFW", NULL, NULL);
    glfwMakeContextCurrent(window);

    glfwSetKeyCallback(window, key_callback);

    int version = gladLoadGL(glfwGetProcAddress);
    printf("GL %d.%d\n", GLAD_VERSION_MAJOR(version), GLAD_VERSION_MINOR(version));

    while (!glfwWindowShouldClose(window)) {
        glfwPollEvents();

        glClearColor(0.7f, 0.9f, 0.1f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        glfwSwapBuffers(window);
    }

    glfwTerminate();

    return 0;
}

[zaruhev]

Issue possibly resolved by fork in PR #464. Please let me know if there are any issues.

Thank you @Dav1dde

[Dav1dde]

As discussed in #464 (comment) we cannot re-produce the issue, closing it until reproducible.