如何使用 GLX 创建“核心”OpenGL 上下文？

如何解决如何使用 GLX 创建“核心”OpenGL 上下文？

我想使用带有“核心”配置文件的 GLX 创建一个 OpenGL 上下文。

为了比较，QOpenGLContext 可以用 QGLFormat::CoreProfile 创建。

我找到了这些说明：Creating a modern OpenGL context 但我没有看到核心/兼容性配置文件。

/* gcc this.c -lGL -lX11 */

#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <GL/glx.h>
#include <X11/Xlib.h>

/*
    License: Public domain

    Contents
    --------
    - Create_display_and_window
    - Create_the_modern_OpenGL_context
    - Show_the_window
    - Application_loop
*/

typedef GLXContext (*glXCreateContextAttribsARBProc)
    (display*,GLXFBConfig,GLXContext,Bool,const int*);

int main()
{
    display* disp = 0;
    Window win = 0;

    /* Create_display_and_window
       -------------------------
       Skip if you already have a display and window */
    disp = XOpendisplay(0);
    win = XCreateSimpleWindow(disp,DefaultRootwindow(disp),10,/* x,y */
                              800,600,/* width,height */
                              0,/* border_width,border */
                              0);       /* background */

    /* Create_the_modern_OpenGL_context
       -------------------------------- */
    static int visual_attribs[] = {
        GLX_RENDER_TYPE,GLX_RGBA_BIT,GLX_DRAWABLE_TYPE,GLX_WINDOW_BIT,GLX_DOUBLEBUFFER,true,GLX_RED_SIZE,1,GLX_GREEN_SIZE,GLX_BLUE_SIZE,None
    };

    int num_fbc = 0;
    GLXFBConfig *fbc = glXChooseFBConfig(disp,DefaultScreen(disp),visual_attribs,&num_fbc);
    if (!fbc) {
        printf("glXChooseFBConfig() Failed\n");
        exit(1);
    }

    /* If we were on Windows (i.e. WGL),we would need to create an old
       dummy OpenGL context here,before calling GetProcAddress(). This is
       unnecessary on Linux (GLX).

       For details,refer to the spec
       (https://www.khronos.org/registry/OpenGL/extensions/ARB/GLX_ARB_get_proc_address.txt)
       which says:
           > Are function pointers context-independent? Yes. The pointer to an
           > extension function can be used with any context [...]

       This is in direct contrast to WGL's wglGetProcAddress. */

    glXCreateContextAttribsARBProc glXCreateContextAttribsARB = 0;
    glXCreateContextAttribsARB =
        (glXCreateContextAttribsARBProc)
        glXGetProcAddress((const glubyte*)"glXCreateContextAttribsARB");

    /* If we were on WiNows,we would destroy the dummy context here. Again,this is unnecessary on Linux.*/

    if (!glXCreateContextAttribsARB) {
        printf("glXCreateContextAttribsARB() not found\n");
        exit(1);
    }

    /* Set desired minimum OpenGL version */
    static int context_attribs[] = {
        GLX_CONTEXT_MAJOR_VERSION_ARB,4,GLX_CONTEXT_MInor_VERSION_ARB,2,None
    };
    /* Create modern OpenGL context */
    GLXContext ctx = glXCreateContextAttribsARB(disp,fbc[0],NULL,context_attribs);
    if (!ctx) {
        printf("Failed to create OpenGL context. Exiting.\n");
        exit(1);
    }

    /* Show_the_window
       --------------- */
    XMapWindow(disp,win);
    glXMakeCurrent(disp,win,ctx);

    int major = 0,minor = 0;
    glGetIntegerv(GL_MAJOR_VERSION,&major);
    glGetIntegerv(GL_MInor_VERSION,&minor);
    printf("OpenGL context created.\nVersion %d.%d\nvendor %s\nRenderer %s\n",major,minor,glGetString(GL_vendOR),glGetString(GL_RENDERER));

    /* Application_loop
       ---------------- */
    while(1) {}

    return 0;
}

khronos.org documentation 说

您可以通过此查询检测上下文支持的配置文件：

glGetIntegerv(GL_CONTEXT_PROFILE_MASK,*);

这可以包含位 GL_CONTEXT_CORE_PROFILE_BIT 或 GL_CONTEXT_COMPATIBILITY_PROFILE_BIT，但不能同时包含两者。

但这是查询已经创建的上下文的功能。

如何使用 GLX 创建核心上下文？