X11 openGL 环境初始化 代码示例

以下是使用 X11 和 OpenGL 初始化一个窗口的示例代码：

#include <X11/Xlib.h>
#include <GL/gl.h>
#include <GL/glx.h>

Display *display;
Window window;
GLXContext glContext;

int main()
{
    // 1. 初始化 X11 窗口
    display = XOpenDisplay(NULL);
    if (display == NULL) {
        printf("Error: cannot connect to X server\n");
        return 1;
    }
    int screen = DefaultScreen(display);
    Window rootWindow = RootWindow(display, screen);
    int visualAttributes[] = {
        GLX_RGBA,
        GLX_DEPTH_SIZE, 24,
        GLX_DOUBLEBUFFER,
        None
    };
    XVisualInfo *visual = glXChooseVisual(display, screen, visualAttributes);
    if (visual == NULL) {
        printf("Error: cannot find suitable visual\n");
        return 1;
    }
    XSetWindowAttributes windowAttributes;
    windowAttributes.colormap = XCreateColormap(display, rootWindow, visual->visual, AllocNone);
    windowAttributes.event_mask = ExposureMask | KeyPressMask;
    window = XCreateWindow(display, rootWindow, 0, 0, 640, 480, 0, visual->depth, InputOutput, visual->visual, CWColormap | CWEventMask, &windowAttributes);
    XMapWindow(display, window);

    // 2. 加载所需的 OpenGL 扩展库
    glXCreateContextAttribsARBProc glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc)glXGetProcAddressARB((const GLubyte*)"glXCreateContextAttribsARB");
    if (glXCreateContextAttribsARB == NULL) {
        printf("Error: cannot load glXCreateContextAttribsARB\n");
        return 1;
    }
    const char *glExtensions = glXQueryExtensionsString(display, screen);
    if (strstr(glExtensions, "GLX_ARB_create_context") == NULL) {
        printf("Error: GLX_ARB_create_context not supported\n");
        return 1;
    }

    // 3. 为 OpenGL 上下文设置像素格式
    typedef GLXContext (*glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLXContext, Bool, const int*);
    int contextAttributes[] = {
        GLX_CONTEXT_MAJOR_VERSION_ARB, 3,
        GLX_CONTEXT_MINOR_VERSION_ARB, 3,
        None
    };
    GLXFBConfig fbConfig = 0;
    int fbConfigsCount = 0;
    GLXFBConfig *fbConfigs = glXChooseFBConfig(display, screen, visualAttributes, &fbConfigsCount);
    if (fbConfigs == NULL || fbConfigsCount == 0) {
        printf("Error: cannot find suitable framebuffer configuration\n");
        return 1;
    }
    for (int i = 0; i < fbConfigsCount; i++) {
        XVisualInfo *vi = glXGetVisualFromFBConfig(display, fbConfigs[i]);
        if (vi != NULL && vi->depth == visual->depth) {
            fbConfig = fbConfigs[i];
            break;
        }
    }
    if (fbConfig == 0) {
        printf("Error: cannot find suitable framebuffer configuration\n");
        return 1;
    }
    glContext = glXCreateContextAttribsARB(display, fbConfig, 0, True, contextAttributes);
    if (glContext == NULL) {
        printf("Error: cannot create OpenGL context\n");
        return 1;
    }

    // 4. 激活 OpenGL 上下文
    glXMakeCurrent(display, window, glContext);

    // 进入主循环
    while (1) {
        XEvent event;
        XNextEvent(display, &event);
        switch (event.type) {
            case Expose:
                glClearColor(0, 0, 0, 1);
                glClear(GL_COLOR_BUFFER_BIT);
                glXSwapBuffers(display, window);
                break;
            case KeyPress:
                XCloseDisplay(display);
                return 0;
        }
    }
}

以上代码使用了 X11 和 GLX 库来创建窗口和 OpenGL 上下文，并在主循环中使用 OpenGL 渲染窗口。注意代码中的注释和错误处理。代码中还使用了 GLX_ARB_create_context 扩展来创建 OpenGL 3.3 上下文，如果需要使用其他版本的 OpenGL，可以修改相应的参数。