Fixed bug 3100 - SetSwapInterval should now be enabled for ANGLE/EGL

Mark Logan 2015-08-24 15:57:50 UTC
In SDL_windowsopengles.c, WIN_GLES_SetSwapInterval is as follows:

WIN_GLES_SetSwapInterval(_THIS, int interval)
{
    /* FIXME: This should call SDL_EGL_SetSwapInterval, but ANGLE has a bug that prevents this
     * from working if we do (the window contents freeze and don't swap properly). So, we ignore
     * the request for now.
     */
    SDL_Log("WARNING: Ignoring SDL_GL_SetSwapInterval call due to ANGLE bug");
    return 0;
}

With a recent version of ANGLE (early July) calling SDL_EGL_SetSwapInterval with a D3D11 backend appears to work just fine. I am working on testing this with D3D9.

--

Alex Szpakowski

I found the bug, it was fixed in 2013. https://bugs.chromium.org/p/angleproject/issues/detail?id=481

In my opinion it should be safe to unconditionally use SetSwapInterval now. Anyone who encounters the bug should update their ANGLE to a version less than 3 years old, especially since they'd be using a SDL version that's 3+ years newer than their ANGLE version.

src/video/windows/SDL_windowsopengles.c

@@ -126,17 +126,6 @@ WIN_GLES_SetupWindow(_THIS, SDL_Window * window)
     return WIN_GLES_MakeCurrent(_this, current_win, current_ctx);    
 }
 
-int
-WIN_GLES_SetSwapInterval(_THIS, int interval)
-{
-    /* FIXME: This should call SDL_EGL_SetSwapInterval, but ANGLE has a bug that prevents this
-     * from working if we do (the window contents freeze and don't swap properly). So, we ignore
-     * the request for now.
-     */
-    SDL_Log("WARNING: Ignoring SDL_GL_SetSwapInterval call due to ANGLE bug");
-    return 0;
-}
-
 #endif /* SDL_VIDEO_DRIVER_WINDOWS && SDL_VIDEO_OPENGL_EGL */
 
 /* vi: set ts=4 sw=4 expandtab: */

src/video/windows/SDL_windowsopengles.h

@@ -33,9 +33,7 @@
 #define WIN_GLES_GetProcAddress SDL_EGL_GetProcAddress
 #define WIN_GLES_UnloadLibrary SDL_EGL_UnloadLibrary
 #define WIN_GLES_GetSwapInterval SDL_EGL_GetSwapInterval
-/* See the WIN_GLES_GetSwapInterval implementation to see why this is commented out */
-/*#define WIN_GLES_SetSwapInterval SDL_EGL_SetSwapInterval*/
-extern int WIN_GLES_SetSwapInterval(_THIS, int interval);
+#define WIN_GLES_SetSwapInterval SDL_EGL_SetSwapInterval
 
 extern int WIN_GLES_LoadLibrary(_THIS, const char *path);
 extern SDL_GLContext WIN_GLES_CreateContext(_THIS, SDL_Window * window);