linux openGL

#include <GL/gl.h>
#include <GL/glx.h>
#include <stdlib.h>
void Render(Display &display, Window &window)
{
    glClear(GL_COLOR_BUFFER_BIT);

    glBegin(GL_TRIANGLES);
    glColor3f(1.0f, 0.0f, 0.0f);
    glVertex2f(400,400);
    glColor3f(0.0f, 1.0f, 0.0f);
    glVertex2f(400,200);
    glColor3f(0.0f, 0.0f, 1.0f);
    glVertex2f(200,200);
    glEnd();

    glFlush();
    glXSwapBuffers(&display, window);
}
int main(int argc, char* argv[])
{
        Display* display = XOpenDisplay(getenv("DISPLAY"));
        int width = 640;
        int height = 480;
        int screen = DefaultScreen(display);
        int screen_width = DisplayWidth(display, screen);
        int screen_height = DisplayHeight(display, screen);
        Window window = XCreateWindow(display, XRootWindow(display, screen), (screen_width - width) / 2,
                                         (screen_height - height) / 2, width, height, 0, CopyFromParent,
                                         InputOutput, DefaultVisual(display, screen), 0, nullptr);

        XMapWindow(display, window);
        int configNum;
        GLXFBConfig* config = glXGetFBConfigs(display, screen, &configNum);
        XVisualInfo* visualInfo = glXGetVisualFromFBConfig(display, *config);
        GLXContext context = glXCreateContext(display, visualInfo, nullptr, false);
        glXMakeCurrent(display, window, context);

        int event_mask = (1 << 25) - 1;
        XSelectInput(display, window, event_mask);  //listen to all types of events
        Atom wmDelete = XInternAtom(display, "WM_DELETE_WINDOW", True);
        XSetWMProtocols(display, window, &wmDelete, 1);
        bool needQuit = false;
        while(needQuit == false) {
            XEvent e;
            XNextEvent(display, &e);
            switch (e.type) {
            case Expose:
                Render(*display, window);
                break;
            case ClientMessage:
                needQuit = true;
                break;
            default:
                break;
            }
        }
        glViewport(0, 0, width, height);
        glClearColor(0, 0, 0, 1);
        glMatrixMode(GL_PROJECTION);
        glOrtho(0, width, 0, height, 0, 1000);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();


        glXDestroyWindow(display, window);
        XDestroyWindow(display, window);
        XCloseDisplay(display);
}