使用 GLFW 生成 window，背景颜色不变

Question

I'm trying to change the background color in a window generated by OpenGL/GLFW and I'm using a similar code than the one in the GLFW docs. I'm on Ubuntu 20.04 and the window background is always black, no matter the parameters in the glClearColor() function.

I tried this on Windows 10 using VS and it worked perfectly, but on Ubuntu it's not working at all. No error messages are generated.

I also followed The Cherno's Sparky game engine series, and tried encapsulating the glClear() function in a class method, but this didn't change anything.

This is the whole code:

#include <iostream>
#include <GL/gl.h>
#include <GLFW/glfw3.h>

int main(int argc, char *argv[])
{
    std::cout << "Hello world!" << std::endl;
    if (!glfwInit())
    {
        // Initialization failed
        exit(EXIT_FAILURE);
    }

    GLFWwindow* window = glfwCreateWindow(640, 480, "My Title", NULL, NULL);
    if (!window)
    {
        // Window or OpenGL context creation failed
        std::cout << "Error creating window!" << std::endl;
        glfwTerminate();
        exit(EXIT_FAILURE);
    }

    glfwMakeContextCurrent(window);
    glfwSwapInterval(1);

    glClearColor(1.0f, 0.0f, 0.0f, 1.0f);

    while (!glfwWindowShouldClose(window)) 
    {
        int width, height;

        glfwGetFramebufferSize(window, &width, &height);

        glViewport(0, 0, width, height);
        glClear(GL_COLOR_BUFFER_BIT);



        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    glfwDestroyWindow(window);

    glfwTerminate();
    exit(EXIT_SUCCESS);

    return 0;
}

I'm supposed to get a window with a red background but it's black.

As additional elements, I'm also using CMake to help configuring and building the project (quite overkill I know), and I believe clang is the compiler used for the project. Maybe that influences the result.

Answer 1

You need an appropriate loader after glfwMakeContextCurrent(window) .

If you are using glad, you should call gladLoadGL(glfwGetProcAddress) after glfwMakeContextCurrent(window) as the official doc suggests here .