Henri Verbeet : winex11: Only use glXSwapBuffersMscOML() for child windows.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 147f9341031b7a808d18a2d3545e19fdd2c7c92a
URL:    http://source.winehq.org/git/wine.git/?a=commit;h=147f9341031b7a808d18a2d3545e19fdd2c7c92a

Author: Henri Verbeet <hverbeet at codeweavers.com>
Date:   Wed Jul 12 18:42:29 2017 +0200

winex11: Only use glXSwapBuffersMscOML() for child windows.

The notion that glXSwapBuffersMscOML() with 0/0/0 target_msc/divisor/remainder
is supposed to behave like glXSwapBuffers() with respect to the swap interval
turns out to have been a misconception on my behalf, the extension spec
doesn't actually say that. Adding to the confusion is the fact that some
drivers do in fact behave like that in practice. It's possible to make
glXSwapBuffersMscOML() use the proper swap interval, but it's much easier to
just use glXSwapBuffers() instead. One consequence of the approach taken in
this patch is that child window buffer swaps aren't necessarily synchronised
to vblank, but ultimately that's up to X11DRV_FLUSH_GL_DRAWABLE, not the
buffer swap. This fixes a regression introduced by commit
e75bc6228ebcbdc1a3877a6ac6954611dedf8a71.

Signed-off-by: Henri Verbeet <hverbeet at codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard at winehq.org>

---

 dlls/winex11.drv/opengl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dlls/winex11.drv/opengl.c b/dlls/winex11.drv/opengl.c
index 28f033d..5eb70a8 100644
--- a/dlls/winex11.drv/opengl.c
+++ b/dlls/winex11.drv/opengl.c
@@ -3356,7 +3356,7 @@ static BOOL glxdrv_wglSwapBuffers( HDC hdc )
         escape.gl_drawable = gl->window;
         /* fall through */
     default:
-        if (pglXSwapBuffersMscOML)
+        if (escape.gl_drawable && pglXSwapBuffersMscOML)
         {
             pglFlush();
             target_sbc = pglXSwapBuffersMscOML( gdi_display, gl->drawable, 0, 0, 0 );