From f67b7c9b80f77435d273047121c805722cb75084 Mon Sep 17 00:00:00 2001
From: Neil Roberts <neil@linux.intel.com>
Date: Tue, 23 Nov 2010 17:24:08 +0000
Subject: [PATCH] Hack to make the GLES2 tri demo use two windows

https://bugs.freedesktop.org/show_bug.cgi?id=31868
---
 src/egl/opengles2/tri.c |   55 ++++++++++++++++++++++++++++++++--------------
 1 files changed, 38 insertions(+), 17 deletions(-)

diff --git a/src/egl/opengles2/tri.c b/src/egl/opengles2/tri.c
index 8981d8a..e8419ef 100644
--- a/src/egl/opengles2/tri.c
+++ b/src/egl/opengles2/tri.c
@@ -315,11 +315,16 @@ make_x_window(Display *x_dpy, EGLDisplay egl_dpy,
    eglBindAPI(EGL_OPENGL_ES_API);
 #endif
 
-   ctx = eglCreateContext(egl_dpy, config, EGL_NO_CONTEXT, ctx_attribs );
-   if (!ctx) {
-      printf("Error: eglCreateContext failed\n");
-      exit(1);
-   }
+   if (*ctxRet)
+     ctx = *ctxRet;
+   else
+     {
+       ctx = eglCreateContext(egl_dpy, config, EGL_NO_CONTEXT, ctx_attribs );
+       if (!ctx) {
+         printf("Error: eglCreateContext failed\n");
+         exit(1);
+       }
+     }
 
    /* test eglQueryContext() */
    {
@@ -353,8 +358,8 @@ make_x_window(Display *x_dpy, EGLDisplay egl_dpy,
 
 
 static void
-event_loop(Display *dpy, Window win,
-           EGLDisplay egl_dpy, EGLSurface egl_surf)
+event_loop(Display *dpy, Window *win,
+           EGLContext egl_ctx, EGLDisplay egl_dpy, EGLSurface *egl_surf)
 {
    while (1) {
       int redraw = 0;
@@ -403,7 +408,19 @@ event_loop(Display *dpy, Window win,
 
       if (redraw) {
          draw();
-         eglSwapBuffers(egl_dpy, egl_surf);
+         eglSwapBuffers(egl_dpy, egl_surf[0]);
+
+         /* Temporarily switch to the other surface and draw to that too */
+         if (!eglMakeCurrent(egl_dpy, egl_surf[1], egl_surf[1], egl_ctx)) {
+           printf("Error: eglMakeCurrent() failed\n");
+         }
+         draw();
+         eglSwapBuffers(egl_dpy, egl_surf[1]);
+
+         /* Switch back to the original surface for the next redraw */
+         if (!eglMakeCurrent(egl_dpy, egl_surf[0], egl_surf[0], egl_ctx)) {
+           printf("Error: eglMakeCurrent() failed\n");
+         }
       }
    }
 }
@@ -423,9 +440,9 @@ main(int argc, char *argv[])
 {
    const int winWidth = 300, winHeight = 300;
    Display *x_dpy;
-   Window win;
-   EGLSurface egl_surf;
-   EGLContext egl_ctx;
+   Window win[2];
+   EGLSurface egl_surf[2];
+   EGLContext egl_ctx = 0;
    EGLDisplay egl_dpy;
    char *dpyName = NULL;
    GLboolean printInfo = GL_FALSE;
@@ -479,10 +496,14 @@ main(int argc, char *argv[])
 
    make_x_window(x_dpy, egl_dpy,
                  "OpenGL ES 2.x tri", 0, 0, winWidth, winHeight,
-                 &win, &egl_ctx, &egl_surf);
+                 win, &egl_ctx, egl_surf);
+   make_x_window(x_dpy, egl_dpy,
+                 "OpenGL ES 2.x tri - win2", 0, 0, winWidth, winHeight,
+                 win + 1, &egl_ctx, egl_surf + 1);
 
-   XMapWindow(x_dpy, win);
-   if (!eglMakeCurrent(egl_dpy, egl_surf, egl_surf, egl_ctx)) {
+   XMapWindow(x_dpy, win[0]);
+   XMapWindow(x_dpy, win[1]);
+   if (!eglMakeCurrent(egl_dpy, egl_surf[0], egl_surf[0], egl_ctx)) {
       printf("Error: eglMakeCurrent() failed\n");
       return -1;
    }
@@ -502,14 +523,14 @@ main(int argc, char *argv[])
     */
    reshape(winWidth, winHeight);
 
-   event_loop(x_dpy, win, egl_dpy, egl_surf);
+   event_loop(x_dpy, win, egl_ctx, egl_dpy, egl_surf);
 
    eglDestroyContext(egl_dpy, egl_ctx);
-   eglDestroySurface(egl_dpy, egl_surf);
+   eglDestroySurface(egl_dpy, egl_surf[0]);
    eglTerminate(egl_dpy);
 
 
-   XDestroyWindow(x_dpy, win);
+   XDestroyWindow(x_dpy, win[0]);
    XCloseDisplay(x_dpy);
 
    return 0;
-- 
1.7.3.16.g9464b