[Bf-blender-cvs] SVN commit: /data/svn/bf-blender [57946] branches/soc-2013-depsgraph_mt/ source/blender/blenkernel/intern/scene.c: Fix for dupli-groups update going wrong

[Sergey Sharybin]

Revision: 57946
          http://projects.blender.org/scm/viewvc.php?view=rev&root=bf-blender&revision=57946
Author:   nazgul
Date:     2013-07-02 19:23:23 +0000 (Tue, 02 Jul 2013)
Log Message:
-----------
Fix for dupli-groups update going wrong

Dupli-groups used to have special case for updating
which is BKE_group_handle_recalc_and_update. This
function calls BKE_object_handle_update for every
object in the group.

This isn't thread-safe, because object could be
updating in separate thread already. And what's
worse dependencies are not known for objects inside
the group, which makes it impossible to schedule
objects from the group in a safe way.

It's even impossible to schedule groups as different
tasks, because groups could share the same objects.

For now used simple but robust solution which is
updating dupli-groups in main thread, handling
groups one-by-one and updating objects from the
group one-by-one as well.

Will work on a proper solution for this later.

Modified Paths:
--------------
    branches/soc-2013-depsgraph_mt/source/blender/blenkernel/intern/scene.c

Modified: branches/soc-2013-depsgraph_mt/source/blender/blenkernel/intern/scene.c
===================================================================
--- branches/soc-2013-depsgraph_mt/source/blender/blenkernel/intern/scene.c	2013-07-02 19:23:19 UTC (rev 57945)
+++ branches/soc-2013-depsgraph_mt/source/blender/blenkernel/intern/scene.c	2013-07-02 19:23:23 UTC (rev 57946)
@@ -1172,32 +1172,22 @@
 
 static void scene_update_object_add_task(void *node, void *user_data);
 
-static void scene_update_single_object(Scene *scene, Scene *scene_parent, Object *object)
+static void scene_update_all_bases(Scene *scene, Scene *scene_parent)
 {
-	BKE_object_handle_update_ex(scene_parent, object, scene->rigidbody_world);
+	Base *base;
 
-	if (object->dup_group && (object->transflag & OB_DUPLIGROUP))
-		BKE_group_handle_recalc_and_update(scene_parent, object, object->dup_group);
+	for (base = scene->base.first; base; base = base->next) {
+		Object *object = base->object;
 
-	/* always update layer, so that animating layers works (joshua july 2010) */
-	/* XXX commented out, this has depsgraph issues anyway - and this breaks setting scenes
-	 * (on scene-set, the base-lay is copied to ob-lay (ton nov 2012) */
-	// base->lay = ob->lay;
-}
+		BKE_object_handle_update_ex(scene_parent, object, scene->rigidbody_world);
 
-static void scene_update_single_base(Scene *scene, Scene *scene_parent, Base *base)
-{
-	Object *object = base->object;
+		if (object->dup_group && (object->transflag & OB_DUPLIGROUP))
+			BKE_group_handle_recalc_and_update(scene_parent, object, object->dup_group);
 
-	scene_update_single_object(scene, scene_parent, object);
-}
-
-static void scene_update_all_bases(Scene *scene, Scene *scene_parent)
-{
-	Base *base;
-
-	for (base = scene->base.first; base; base = base->next) {
-		scene_update_single_base(scene, scene_parent, base);
+		/* always update layer, so that animating layers works (joshua july 2010) */
+		/* XXX commented out, this has depsgraph issues anyway - and this breaks setting scenes
+		 * (on scene-set, the base-lay is copied to ob-lay (ton nov 2012) */
+		// base->lay = ob->lay;
 	}
 }
 
@@ -1208,10 +1198,17 @@
 	ThreadedObjectUpdateState *state = (ThreadedObjectUpdateState *) BLI_task_pool_userdata(pool);
 	void *node = taskdata;
 	Object *object = DAG_threaded_update_get_node_object(node);
+	Scene *scene = state->scene;
+	Scene *scene_parent = state->scene_parent;
 
 	if (object) {
 		PRINT("Thread %d: update object %s\n", threadid, object->id.name);
-		scene_update_single_object(state->scene, state->scene_parent, object);
+
+		/* We only update object itself here, dupli-group will be updated
+		 * separately from main thread because of we've got no idea about
+		 * dependnecies inside the group.
+		 */
+		BKE_object_handle_update_ex(scene_parent, object, scene->rigidbody_world);
 	}
 	else {
 		PRINT("Threda %d: update node %s\n", threadid,
@@ -1314,6 +1311,32 @@
 	BLI_end_threaded_malloc();
 
 	BLI_spin_end(&state.lock);
+
+	/* XXX: Weak, very weak!
+	 *
+	 * We update dupligroups in single thread! :S
+	 *
+	 * This is because we've got absolutely no idea about dependencies
+	 * inside the group and we only know order of objects in which we
+	 * need to perform objects update.
+	 *
+	 * We even can not update different groups in different threads,
+	 * because groups could share the objects and detecting whether
+	 * object is updating in multiple threads is not so much easy.
+	 *
+	 * This is solvable with local group dependency graph or expanding
+	 * current dependency graph to be aware of dependencies inside
+	 * groups.
+	 */
+	{
+		Base *base;
+		for (base = scene->base.first; base; base = base->next) {
+			Object *object = base->object;
+
+			if (object->dup_group && (object->transflag & OB_DUPLIGROUP))
+				BKE_group_handle_recalc_and_update(scene_parent, object, object->dup_group);
+		}
+	}
 }
 
 static void scene_update_objects(Scene *scene, Scene *scene_parent)