Add support for quad-buffer stereo

Track the stereo status of windows using the new EXT_stereo_tree
GLX extension.

When stereo is enabled or disabled, a restart is triggered via
meta_restart() after a timeout, setting a _META_ENABLE_STEREO
property on the root window to indicate whether we should
turn on a stereo stage for clutter. The property avoids a loop,
since we need to enable stereo *before* initializing Clutter and GL,
but we need GL to figure out whether we have stereo windows.

Stereo windows are drawn to the stage using new functionality
in Cogl to setup a stereo context, select which buffer to draw
to, and draw either the left or right buffer of a stereo
texture_from_pixmap.

src/Makefile.am

@@ -319,6 +319,8 @@ libmutter_@LIBMUTTER_API_VERSION@_la_SOURCES =	\
 	core/stack.h				\
 	core/stack-tracker.c			\
 	core/stack-tracker.h			\
+	core/stereo.c				\
+	core/stereo.h				\
 	core/util.c				\
 	meta/util.h				\
 	core/util-private.h			\

src/compositor/compositor-private.h

@@ -21,6 +21,10 @@ struct _MetaCompositor
   gint64          server_time_query_time;
   gint64          server_time_offset;
 
+  int             glx_opcode;
+  guint           stereo_tree_ext : 1;
+  guint           have_stereo_windows : 1;
+
   guint           server_time_is_monotonic_time : 1;
   guint           no_mipmaps  : 1;
 
@@ -61,6 +65,11 @@ void     meta_end_modal_for_plugin   (MetaCompositor   *compositor,
 gint64 meta_compositor_monotonic_time_to_server_time (MetaDisplay *display,
                                                       gint64       monotonic_time);
 
+gboolean meta_compositor_window_is_stereo     (MetaScreen *screen,
+                                               Window      xwindow);
+void     meta_compositor_select_stereo_notify (MetaScreen *screen,
+                                               Window      xwindow);
+
 void meta_compositor_flash_window (MetaCompositor *compositor,
                                    MetaWindow     *window);
 

src/compositor/compositor.c

@@ -70,6 +70,8 @@
 #include "meta-window-group-private.h"
 #include "window-private.h" /* to check window->hidden */
 #include "display-private.h" /* for meta_display_lookup_x_window() and meta_display_cancel_touch() */
+#include "stack-tracker.h"
+#include "stereo.h"
 #include "util-private.h"
 #include "backends/meta-dnd-private.h"
 #include "frame.h"
@@ -487,6 +489,97 @@ redirect_windows (MetaScreen *screen)
     }
 }
 
+#define GLX_STEREO_TREE_EXT        0x20F5
+#define GLX_STEREO_NOTIFY_MASK_EXT 0x00000001
+#define GLX_STEREO_NOTIFY_EXT      0x00000000
+
+typedef struct {
+  int type;
+  unsigned long serial;
+  Bool send_event;
+  Display *display;
+  int extension;
+  int evtype;
+  Drawable window;
+  Bool stereo_tree;
+} StereoNotifyEvent;
+
+static gboolean
+screen_has_stereo_tree_ext (MetaScreen *screen)
+{
+  MetaDisplay *display = meta_screen_get_display (screen);
+  Display     *xdisplay = meta_display_get_xdisplay (display);
+  const char  *extensions_string;
+
+  static const char * (*query_extensions_string) (Display *display,
+                                                  int      screen);
+
+  if (query_extensions_string == NULL)
+    query_extensions_string =
+      (const char * (*) (Display *, int))
+      cogl_get_proc_address ("glXQueryExtensionsString");
+
+  extensions_string = query_extensions_string (xdisplay,
+                                               meta_screen_get_screen_number (screen));
+
+  return extensions_string && strstr (extensions_string, "EXT_stereo_tree") != 0;
+}
+
+#include <GL/gl.h>
+
+gboolean
+meta_compositor_window_is_stereo (MetaScreen *screen,
+                                  Window      xwindow)
+{
+  MetaCompositor *compositor = get_compositor_for_screen (screen);
+  MetaDisplay    *display = meta_screen_get_display (screen);
+  Display        *xdisplay = meta_display_get_xdisplay (display);
+
+  static int (*query_drawable) (Display      *dpy,
+                                Drawable      draw,
+                                int           attribute,
+                                unsigned int *value);
+
+  if (compositor->stereo_tree_ext)
+    {
+      unsigned int stereo_tree = 0;
+
+      if (query_drawable == NULL)
+        query_drawable =
+          (int (*) (Display *, Drawable, int, unsigned int *))
+          cogl_get_proc_address ("glXQueryDrawable");
+
+      query_drawable (xdisplay, xwindow, GLX_STEREO_TREE_EXT, &stereo_tree);
+
+      return stereo_tree != 0;
+    }
+  else
+    return FALSE;
+}
+
+void
+meta_compositor_select_stereo_notify (MetaScreen *screen,
+                                      Window      xwindow)
+{
+  MetaCompositor *compositor = get_compositor_for_screen (screen);
+  MetaDisplay    *display = meta_screen_get_display (screen);
+  Display        *xdisplay = meta_display_get_xdisplay (display);
+
+  static void (*select_event) (Display      *dpy,
+                               Drawable      draw,
+                               unsigned long event_mask);
+
+  if (compositor->stereo_tree_ext)
+    {
+      if (select_event == NULL)
+        select_event =
+          (void (*) (Display *, Drawable, unsigned long))
+          cogl_get_proc_address ("glXSelectEvent");
+
+      select_event (xdisplay, xwindow, GLX_STEREO_NOTIFY_MASK_EXT);
+    }
+}
+
 void
 meta_compositor_manage (MetaCompositor *compositor)
 {
@@ -495,6 +588,8 @@ meta_compositor_manage (MetaCompositor *compositor)
   MetaScreen *screen = display->screen;
   MetaBackend *backend = meta_get_backend ();
 
+  compositor->stereo_tree_ext = screen_has_stereo_tree_ext (screen);
+
   meta_screen_set_cm_selection (display->screen);
 
   compositor->stage = meta_backend_get_stage (backend);
@@ -759,6 +854,23 @@ meta_compositor_process_event (MetaCompositor *compositor,
       if (window)
         process_damage (compositor, (XDamageNotifyEvent *) event, window);
     }
+  else if (!meta_is_wayland_compositor () &&
+           event->type == GenericEvent &&
+           event->xcookie.extension == compositor->glx_opcode)
+    {
+      if (event->xcookie.evtype == GLX_STEREO_NOTIFY_EXT)
+        {
+          StereoNotifyEvent *stereo_event = (StereoNotifyEvent *)(event->xcookie.data);
+          window = meta_display_lookup_x_window (compositor->display, stereo_event->window);
+
+          if (window != NULL)
+            {
+              MetaWindowActor *window_actor = META_WINDOW_ACTOR (meta_window_get_compositor_private (window));
+              meta_window_actor_stereo_notify (window_actor, stereo_event->stereo_tree);
+              meta_stack_tracker_queue_sync_stack (window->screen->stack_tracker);
+            }
+        }
+    }
 
   if (compositor->have_x11_sync_object)
     meta_sync_ring_handle_event (event);
@@ -969,6 +1081,7 @@ meta_compositor_sync_stack (MetaCompositor  *compositor,
 			    GList	    *stack)
 {
   GList *old_stack;
+  int stereo_window_count = 0;
 
   /* This is painful because hidden windows that we are in the process
    * of animating out of existence. They'll be at the bottom of the
@@ -1044,6 +1157,8 @@ meta_compositor_sync_stack (MetaCompositor  *compositor,
        * near the front of the other.)
        */
       compositor->windows = g_list_prepend (compositor->windows, actor);
+      if (meta_window_actor_is_stereo (actor))
+        stereo_window_count++;
 
       stack = g_list_remove (stack, window);
       old_stack = g_list_remove (old_stack, actor);
@@ -1051,6 +1166,8 @@ meta_compositor_sync_stack (MetaCompositor  *compositor,
 
   sync_actor_stacking (compositor);
 
+  meta_stereo_set_have_stereo_windows (stereo_window_count > 0);
+
   if (compositor->top_window_actor)
     g_signal_handlers_disconnect_by_func (compositor->top_window_actor,
                                           on_top_window_actor_destroyed,
@@ -1259,6 +1376,17 @@ meta_compositor_new (MetaDisplay *display)
                                            meta_post_paint_func,
                                            compositor,
                                            NULL);
+  if (!meta_is_wayland_compositor ())
+    {
+      Display *xdisplay = meta_display_get_xdisplay (display);
+      int glx_major_opcode, glx_first_event, glx_first_error;
+
+      if (XQueryExtension (xdisplay,
+                           "GLX",
+                           &glx_major_opcode, &glx_first_event, &glx_first_error))
+        compositor->glx_opcode = glx_major_opcode;
+    }
+
   return compositor;
 }
 

src/compositor/meta-shaped-texture-private.h

@@ -30,8 +30,9 @@
 #include <meta/meta-shaped-texture.h>
 
 ClutterActor *meta_shaped_texture_new (void);
-void meta_shaped_texture_set_texture (MetaShapedTexture *stex,
+void meta_shaped_texture_set_textures (MetaShapedTexture *stex,
-                                      CoglTexture       *texture);
+                                       CoglTexture       *texture,
+                                       CoglTexture       *texture_right);
 void meta_shaped_texture_set_is_y_inverted (MetaShapedTexture *stex,
                                             gboolean           is_y_inverted);
 void meta_shaped_texture_set_snippet (MetaShapedTexture *stex,

src/compositor/meta-shaped-texture.c

@@ -89,8 +89,10 @@ typedef struct
 struct _MetaShapedTexturePrivate
 {
   MetaTextureTower *paint_tower;
+  MetaTextureTower *paint_tower_right;
 
   CoglTexture *texture;
+  CoglTexture *texture_right;
   CoglTexture *mask_texture;
   CoglSnippet *snippet;
 
@@ -161,8 +163,10 @@ meta_shaped_texture_init (MetaShapedTexture *self)
   priv = self->priv = META_SHAPED_TEXTURE_GET_PRIVATE (self);
 
   priv->paint_tower = meta_texture_tower_new ();
+  priv->paint_tower_right = NULL; /* demand create */
 
   priv->texture = NULL;
+  priv->texture_right = NULL;
   priv->mask_texture = NULL;
   priv->create_mipmaps = TRUE;
   priv->is_y_inverted = TRUE;
@@ -229,11 +233,11 @@ meta_shaped_texture_dispose (GObject *object)
   MetaShapedTexture *self = (MetaShapedTexture *) object;
   MetaShapedTexturePrivate *priv = self->priv;
 
-  if (priv->paint_tower)
+  g_clear_pointer (&priv->paint_tower, meta_texture_tower_free);
-    meta_texture_tower_free (priv->paint_tower);
+  g_clear_pointer (&priv->paint_tower_right, meta_texture_tower_free);
-  priv->paint_tower = NULL;
 
   g_clear_pointer (&priv->texture, cogl_object_unref);
+  g_clear_pointer (&priv->texture_right, cogl_object_unref);
   g_clear_pointer (&priv->opaque_region, cairo_region_destroy);
 
   meta_shaped_texture_set_mask_texture (self, NULL);
@@ -431,8 +435,9 @@ paint_clipped_rectangle (CoglFramebuffer       *fb,
 }
 
 static void
-set_cogl_texture (MetaShapedTexture *stex,
+set_cogl_textures (MetaShapedTexture *stex,
-                  CoglTexture       *cogl_tex)
+                   CoglTexture       *cogl_tex,
+                   CoglTexture       *cogl_tex_right)
 {
   MetaShapedTexturePrivate *priv;
   guint width, height;
@@ -443,10 +448,13 @@ set_cogl_texture (MetaShapedTexture *stex,
 
   if (priv->texture)
     cogl_object_unref (priv->texture);
+  if (priv->texture_right)
+    cogl_object_unref (priv->texture_right);
 
   g_clear_pointer (&priv->saved_base_surface, cairo_surface_destroy);
 
   priv->texture = cogl_tex;
+  priv->texture_right = cogl_tex_right;
 
   if (cogl_tex != NULL)
     {
@@ -460,6 +468,9 @@ set_cogl_texture (MetaShapedTexture *stex,
       height = 0;
     }
 
+  if (cogl_tex_right != NULL)
+    cogl_object_ref (cogl_tex_right);
+
   if (priv->tex_width != width ||
       priv->tex_height != height)
     {
@@ -475,8 +486,23 @@ set_cogl_texture (MetaShapedTexture *stex,
    * previous buffer. We only queue a redraw in response to surface
    * damage. */
 
+  if (cogl_tex_right != NULL)
+    {
+      if (priv->paint_tower_right == NULL)
+        priv->paint_tower_right = meta_texture_tower_new ();
+    }
+  else
+    {
+      g_clear_pointer (&priv->paint_tower_right, meta_texture_tower_free);
+    }
+
   if (priv->create_mipmaps)
+    {
       meta_texture_tower_set_base_texture (priv->paint_tower, cogl_tex);
+
+      if (priv->paint_tower_right)
+        meta_texture_tower_set_base_texture (priv->paint_tower_right, cogl_tex_right);
+    }
 }
 
 static void
@@ -485,6 +511,7 @@ do_paint (MetaShapedTexture *stex,
           CoglTexture       *paint_tex,
           cairo_region_t    *clip_region)
 {
+  ClutterActor *actor = CLUTTER_ACTOR (stex);
   MetaShapedTexturePrivate *priv = stex->priv;
   guint tex_width, tex_height;
   guchar opacity;
@@ -700,7 +727,9 @@ meta_shaped_texture_paint (ClutterActor *actor)
   MetaShapedTexture *stex = META_SHAPED_TEXTURE (actor);
   MetaShapedTexturePrivate *priv = stex->priv;
   CoglTexture *paint_tex = NULL;
+  CoglTexture *paint_tex_right = NULL;
   CoglFramebuffer *fb;
+  gboolean stereo;
 
   if (!priv->texture)
     return;
@@ -737,7 +766,32 @@ meta_shaped_texture_paint (ClutterActor *actor)
     return;
 
   fb = cogl_get_draw_framebuffer ();
-  do_paint (META_SHAPED_TEXTURE (actor), fb, paint_tex, priv->clip_region);
+
+  stereo = priv->texture_right && cogl_framebuffer_get_is_stereo (fb);
+
+  if (stereo)
+    {
+      if (priv->create_mipmaps)
+	paint_tex_right = meta_texture_tower_get_paint_texture (priv->paint_tower_right);
+
+      if (!paint_tex_right)
+	paint_tex_right = COGL_TEXTURE (priv->texture_right);
+    }
+  else
+    paint_tex_right = NULL;
+
+  if (stereo)
+    cogl_framebuffer_set_stereo_mode (fb, COGL_STEREO_LEFT);
+  do_paint (stex, fb, paint_tex, priv->clip_region);
+  if (stereo)
+    cogl_framebuffer_set_stereo_mode (fb, COGL_STEREO_BOTH);
+
+  if (paint_tex_right != NULL)
+    {
+      cogl_framebuffer_set_stereo_mode (fb, COGL_STEREO_RIGHT);
+      do_paint (stex, fb, paint_tex_right, priv->clip_region);
+      cogl_framebuffer_set_stereo_mode (fb, COGL_STEREO_BOTH);
+    }
 }
 
 static void
@@ -859,6 +913,12 @@ meta_shaped_texture_set_create_mipmaps (MetaShapedTexture *stex,
       priv->create_mipmaps = create_mipmaps;
       base_texture = create_mipmaps ? priv->texture : NULL;
       meta_texture_tower_set_base_texture (priv->paint_tower, base_texture);
+
+      if (priv->paint_tower_right)
+        {
+          base_texture = create_mipmaps ? priv->texture_right : NULL;
+          meta_texture_tower_set_base_texture (priv->paint_tower_right, base_texture);
+        }
     }
 }
 
@@ -987,6 +1047,8 @@ meta_shaped_texture_update_area (MetaShapedTexture *stex,
   shrink_backing_region (stex, &clip);
 
   meta_texture_tower_update_area (priv->paint_tower, x, y, width, height);
+  if (priv->paint_tower_right)
+    meta_texture_tower_update_area (priv->paint_tower_right, x, y, width, height);
 
   unobscured_region = effective_unobscured_region (stex);
   if (unobscured_region)
@@ -1019,17 +1081,18 @@ meta_shaped_texture_update_area (MetaShapedTexture *stex,
 }
 
 /**
- * meta_shaped_texture_set_texture:
+ * meta_shaped_texture_set_textures:
  * @stex: The #MetaShapedTexture
  * @pixmap: The #CoglTexture to display
  */
 void
-meta_shaped_texture_set_texture (MetaShapedTexture *stex,
+meta_shaped_texture_set_textures (MetaShapedTexture *stex,
-                                 CoglTexture       *texture)
+                                  CoglTexture       *texture,
+                                  CoglTexture       *texture_right)
 {
   g_return_if_fail (META_IS_SHAPED_TEXTURE (stex));
 
-  set_cogl_texture (stex, texture);
+  set_cogl_textures (stex, texture, texture_right);
 }
 
 /**

src/compositor/meta-surface-actor-wayland.c

@@ -187,7 +187,7 @@ meta_surface_actor_wayland_dispose (GObject *object)
   MetaShapedTexture *stex =
     meta_surface_actor_get_texture (META_SURFACE_ACTOR (self));
 
-  meta_shaped_texture_set_texture (stex, NULL);
+  meta_shaped_texture_set_textures (stex, NULL, NULL);
   if (priv->surface)
     {
       g_object_remove_weak_pointer (G_OBJECT (priv->surface),

src/compositor/meta-surface-actor-x11.c

@@ -31,6 +31,7 @@
 #include <cogl/winsys/cogl-texture-pixmap-x11.h>
 
 #include <meta/errors.h>
+#include "compositor-private.h"
 #include "window-private.h"
 #include "meta-shaped-texture-private.h"
 #include "meta-cullable.h"
@@ -43,6 +44,7 @@ struct _MetaSurfaceActorX11Private
   MetaDisplay *display;
 
   CoglTexture *texture;
+  CoglTexture *texture_right;
   Pixmap pixmap;
   Damage damage;
 
@@ -58,6 +60,8 @@ struct _MetaSurfaceActorX11Private
   guint size_changed : 1;
 
   guint unredirected   : 1;
+
+  guint stereo : 1;
 };
 typedef struct _MetaSurfaceActorX11Private MetaSurfaceActorX11Private;
 
@@ -94,7 +98,7 @@ detach_pixmap (MetaSurfaceActorX11 *self)
    * you are supposed to be able to free a GLXPixmap after freeing the underlying
    * pixmap, but it certainly doesn't work with current DRI/Mesa
    */
-  meta_shaped_texture_set_texture (stex, NULL);
+  meta_shaped_texture_set_textures (stex, NULL, NULL);
   cogl_flush ();
 
   meta_error_trap_push (display);
@@ -103,6 +107,7 @@ detach_pixmap (MetaSurfaceActorX11 *self)
   meta_error_trap_pop (display);
 
   g_clear_pointer (&priv->texture, cogl_object_unref);
+  g_clear_pointer (&priv->texture_right, cogl_object_unref);
 }
 
 static void
@@ -114,23 +119,35 @@ set_pixmap (MetaSurfaceActorX11 *self,
   CoglContext *ctx = clutter_backend_get_cogl_context (clutter_get_default_backend ());
   MetaShapedTexture *stex = meta_surface_actor_get_texture (META_SURFACE_ACTOR (self));
   CoglError *error = NULL;
-  CoglTexture *texture;
+  CoglTexturePixmapX11 *texture;
+  CoglTexturePixmapX11 *texture_right;
 
   g_assert (priv->pixmap == None);
   priv->pixmap = pixmap;
 
-  texture = COGL_TEXTURE (cogl_texture_pixmap_x11_new (ctx, priv->pixmap, FALSE, &error));
+  if (priv->stereo)
+    texture = cogl_texture_pixmap_x11_new_left (ctx, pixmap, FALSE, &error);
+  else
+    texture = cogl_texture_pixmap_x11_new (ctx, pixmap, FALSE, &error);
+
+  if (priv->stereo)
+    texture_right = cogl_texture_pixmap_x11_new_right (texture);
+  else
+    texture_right = NULL;
 
   if (error != NULL)
     {
       g_warning ("Failed to allocate stex texture: %s", error->message);
       cogl_error_free (error);
     }
-  else if (G_UNLIKELY (!cogl_texture_pixmap_x11_is_using_tfp_extension (COGL_TEXTURE_PIXMAP_X11 (texture))))
+  else if (G_UNLIKELY (!cogl_texture_pixmap_x11_is_using_tfp_extension (texture)))
     g_warning ("NOTE: Not using GLX TFP!\n");
 
-  priv->texture = texture;
+  priv->texture = COGL_TEXTURE (texture);
-  meta_shaped_texture_set_texture (stex, texture);
+  if (priv->stereo)
+    priv->texture_right = COGL_TEXTURE (texture_right);
+
+  meta_shaped_texture_set_textures (stex, COGL_TEXTURE (texture), COGL_TEXTURE (texture_right));
 }
 
 static void
@@ -433,8 +450,8 @@ reset_texture (MetaSurfaceActorX11 *self)
   /* Setting the texture to NULL will cause all the FBO's cached by the
    * shaped texture's MetaTextureTower to be discarded and recreated.
    */
-  meta_shaped_texture_set_texture (stex, NULL);
+  meta_shaped_texture_set_textures (stex, NULL, NULL);
-  meta_shaped_texture_set_texture (stex, priv->texture);
+  meta_shaped_texture_set_textures (stex, priv->texture, priv->texture_right);
 }
 
 MetaSurfaceActor *
@@ -443,12 +460,17 @@ meta_surface_actor_x11_new (MetaWindow *window)
   MetaSurfaceActorX11 *self = g_object_new (META_TYPE_SURFACE_ACTOR_X11, NULL);
   MetaSurfaceActorX11Private *priv = meta_surface_actor_x11_get_instance_private (self);
   MetaDisplay *display = meta_window_get_display (window);
+  Window xwindow;
 
   g_assert (!meta_is_wayland_compositor ());
 
   priv->window = window;
   priv->display = display;
 
+  xwindow = meta_window_x11_get_toplevel_xwindow (window);
+  priv->stereo = meta_compositor_window_is_stereo (display->screen, xwindow);
+  meta_compositor_select_stereo_notify (display->screen, xwindow);
+
   g_signal_connect_object (priv->display, "gl-video-memory-purged",
                            G_CALLBACK (reset_texture), self, G_CONNECT_SWAPPED);
 
@@ -479,3 +501,21 @@ meta_surface_actor_x11_set_size (MetaSurfaceActorX11 *self,
   priv->last_height = height;
   meta_shaped_texture_set_fallback_size (stex, width, height);
 }
+
+void
+meta_surface_actor_x11_stereo_notify (MetaSurfaceActorX11 *self,
+                                      gboolean             stereo_tree)
+{
+  MetaSurfaceActorX11Private *priv = meta_surface_actor_x11_get_instance_private (self);
+
+  priv->stereo = stereo_tree != FALSE;
+  detach_pixmap (self);
+}
+
+gboolean
+meta_surface_actor_x11_is_stereo (MetaSurfaceActorX11 *self)
+{
+  MetaSurfaceActorX11Private *priv = meta_surface_actor_x11_get_instance_private (self);
+
+  return priv->stereo;
+}

src/compositor/meta-surface-actor-x11.h

@@ -64,6 +64,11 @@ MetaSurfaceActor * meta_surface_actor_x11_new (MetaWindow *window);
 void meta_surface_actor_x11_set_size (MetaSurfaceActorX11 *self,
                                       int width, int height);
 
+void meta_surface_actor_x11_stereo_notify (MetaSurfaceActorX11 *self,
+                                           gboolean             stereo_tree);
+
+gboolean meta_surface_actor_x11_is_stereo (MetaSurfaceActorX11 *self);
+
 G_END_DECLS
 
 #endif /* __META_SURFACE_ACTOR_X11_H__ */

src/compositor/meta-window-actor-private.h

@@ -60,4 +60,9 @@ MetaSurfaceActor *meta_window_actor_get_surface (MetaWindowActor *self);
 void meta_window_actor_update_surface (MetaWindowActor *self);
 MetaWindowActor *meta_window_actor_from_window (MetaWindow *window);
 
+void meta_window_actor_stereo_notify (MetaWindowActor *actor,
+                                      gboolean         stereo_tree);
+
+gboolean meta_window_actor_is_stereo (MetaWindowActor *actor);
+
 #endif /* META_WINDOW_ACTOR_PRIVATE_H */

src/compositor/meta-window-actor.c

@@ -2321,3 +2321,25 @@ screen_cast_window_iface_init (MetaScreenCastWindowInterface *iface)
   iface->transform_relative_position = meta_window_actor_transform_relative_position;
   iface->capture_into = meta_window_actor_capture_into;
 }
+
+void
+meta_window_actor_stereo_notify (MetaWindowActor *self,
+                                 gboolean         stereo_tree)
+{
+  MetaWindowActorPrivate *priv = self->priv;
+
+  if (META_IS_SURFACE_ACTOR_X11 (priv->surface))
+    meta_surface_actor_x11_stereo_notify (META_SURFACE_ACTOR_X11 (priv->surface),
+                                          stereo_tree);
+}
+
+gboolean
+meta_window_actor_is_stereo (MetaWindowActor *self)
+{
+  MetaWindowActorPrivate *priv = self->priv;
+
+  if (META_IS_SURFACE_ACTOR_X11 (priv->surface))
+    return meta_surface_actor_x11_is_stereo (META_SURFACE_ACTOR_X11 (priv->surface));
+  else
+    return FALSE;
+}

src/core/main.c

@@ -47,6 +47,7 @@
 #include <meta/main.h>
 #include "util-private.h"
 #include "display-private.h"
+#include "stereo.h"
 #include <meta/errors.h>
 #include "ui.h"
 #include <meta/prefs.h>
@@ -582,6 +583,9 @@ meta_init (void)
 
   meta_init_backend (backend_gtype);
 
+  if (!meta_is_wayland_compositor ())
+    meta_stereo_init ();
+
   meta_clutter_init ();
 
 #ifdef HAVE_WAYLAND

src/core/stereo.c

@@ -0,0 +1,153 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/*
+ * Copyright (C) 2014 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * SECTION:stereo
+ * @short_description: Keep track of whether we are a stereo compositor
+ *
+ * With GLX, we need to use a different GL context for stereo and
+ * non-stereo support. Support for multiple GL contexts is unfinished
+ * in Cogl and entirely lacking in Clutter, so it's by far easier
+ * to just restart Mutter when we detect a stereo window.
+ *
+ * A property _MUTTER_ENABLE_STEREO is maintained on the root window
+ * to know whether we should initialize clutter for stereo or not.
+ * When the presence or absence of stereo windows mismatches the
+ * stereo-enabled state for a sufficiently long period of time,
+ * we restart Mutter.
+ */
+
+#include <config.h>
+
+#include <clutter/x11/clutter-x11.h>
+#include <gio/gunixinputstream.h>
+#include <X11/Xatom.h>
+
+#include <meta/main.h>
+#include "ui.h"
+#include <meta/util.h>
+#include "display-private.h"
+#include "stereo.h"
+#include "util-private.h"
+
+static guint stereo_switch_id = 0;
+static gboolean stereo_enabled = FALSE;
+/* -1 so the first time meta_stereo_set_have_stereo_windows() is called
+ * we avoid the short-circuit and set up a timeout to restart
+ * if necessary */
+static gboolean stereo_have_windows = (gboolean)-1;
+static gboolean stereo_restart = FALSE;
+
+#define STEREO_ENABLE_WAIT 1000
+#define STEREO_DISABLE_WAIT 5000
+
+void
+meta_stereo_init (void)
+{
+  Display *xdisplay;
+  Window root;
+  Atom atom_enable_stereo;
+  Atom type;
+  int format;
+  unsigned long n_items, bytes_after;
+  guchar *data;
+
+  xdisplay = XOpenDisplay (NULL);
+  if (xdisplay == NULL)
+    meta_fatal ("Unable to open X display %s\n", XDisplayName (NULL));
+
+  root = DefaultRootWindow (xdisplay);
+  atom_enable_stereo = XInternAtom (xdisplay, "_MUTTER_ENABLE_STEREO", False);
+
+  XGetWindowProperty (xdisplay, root, atom_enable_stereo,
+                      0, 1, False, XA_INTEGER,
+                      &type, &format, &n_items, &bytes_after, &data);
+  if (type == XA_INTEGER)
+    {
+      if (format == 32 && n_items == 1 && bytes_after == 0)
+        {
+          stereo_enabled = *(long *)data;
+        }
+      else
+        {
+          meta_warning ("Bad value for _MUTTER_ENABLE_STEREO property\n");
+        }
+
+      XFree (data);
+    }
+  else if (type != None)
+    {
+      meta_warning ("Bad type for _MUTTER_ENABLE_STEREO property\n");
+    }
+
+  meta_verbose ("On startup, _MUTTER_ENABLE_STEREO=%s",
+                stereo_enabled ? "yes" : "no");
+  clutter_x11_set_use_stereo_stage (stereo_enabled);
+  XCloseDisplay (xdisplay);
+}
+
+static gboolean
+meta_stereo_switch (gpointer data)
+{
+  stereo_switch_id = 0;
+  stereo_restart = TRUE;
+
+  meta_restart (stereo_have_windows ?
+                _("Enabling stereo...") :
+                _("Disabling stereo..."));
+
+  return FALSE;
+}
+
+void
+meta_stereo_set_have_stereo_windows (gboolean have_windows)
+{
+  have_windows = have_windows != FALSE;
+
+  if (!stereo_restart && have_windows != stereo_have_windows)
+    {
+      MetaDisplay *display = meta_get_display ();
+      Display *xdisplay = meta_display_get_xdisplay (display);
+      Window root = DefaultRootWindow (xdisplay);
+      Atom atom_enable_stereo = XInternAtom (xdisplay, "_MUTTER_ENABLE_STEREO", False);
+      long value;
+
+      stereo_have_windows = have_windows;
+
+      if (stereo_have_windows)
+        meta_verbose ("Detected stereo windows\n");
+      else
+        meta_verbose ("No stereo windows detected\n");
+
+      value = stereo_have_windows;
+      XChangeProperty (xdisplay, root,
+                       atom_enable_stereo, XA_INTEGER, 32,
+                       PropModeReplace, (guchar *)&value, 1);
+
+      if (stereo_switch_id != 0)
+        {
+          g_source_remove (stereo_switch_id);
+          stereo_switch_id = 0;
+        }
+
+      if (stereo_have_windows != stereo_enabled)
+        stereo_switch_id = g_timeout_add (stereo_have_windows ? STEREO_ENABLE_WAIT : STEREO_DISABLE_WAIT,
+                                          meta_stereo_switch, NULL);
+    }
+}

src/core/stereo.h

@@ -0,0 +1,28 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/*
+ * Copyright (C) 2014 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef META_STEREO_H
+#define META_STEREO_H
+
+void     meta_stereo_init                    (void);
+void     meta_stereo_set_have_stereo_windows (gboolean have_windows);
+gboolean meta_stereo_is_restart              (void);
+void     meta_stereo_finish_restart          (void);
+
+#endif

src/wayland/meta-wayland-surface.c

@@ -676,7 +676,7 @@ meta_wayland_surface_apply_pending_state (MetaWaylandSurface      *surface,
               snippet = meta_wayland_buffer_create_snippet (pending->buffer);
               is_y_inverted = meta_wayland_buffer_is_y_inverted (pending->buffer);
 
-              meta_shaped_texture_set_texture (stex, texture);
+              meta_shaped_texture_set_textures (stex, texture, NULL);
               meta_shaped_texture_set_snippet (stex, snippet);
               meta_shaped_texture_set_is_y_inverted (stex, is_y_inverted);
               g_clear_pointer (&snippet, cogl_object_unref);