Fix #33113: cycles not rendering motion blur correct with dying particles.

There were a bunch of other issues with dupli motion blur and syncing, the problem
being that there was no proper way to detect corresponding duplis between frames
or updates. As a solution, a persistent_id was added to the DupliObject. It's an
extension of the previous index value, with one index for each dupli level. This
can be used to reliably find matching dupli objects between frames. Works with
nested duplis, multiple particle systems, etc.

1 files changed, 46 insertions, 29 deletions

diff --git a/intern/cycles/blender/blender_object.cpp b/intern/cycles/blender/blender_object.cpp
index 1b920249733..a18cb79c102 100644
--- a/intern/cycles/blender/blender_object.cpp
+++ b/intern/cycles/blender/blender_object.cpp
@@ -86,11 +86,11 @@ static uint object_ray_visibility(BL::Object b_ob)
 
 /* Light */
 
-void BlenderSync::sync_light(BL::Object b_parent, int b_index, BL::Object b_ob, Transform& tfm)
+void BlenderSync::sync_light(BL::Object b_parent, int persistent_id[OBJECT_PERSISTENT_ID_SIZE], BL::Object b_ob, Transform& tfm)
 {
 	/* test if we need to sync */
 	Light *light;
-	ObjectKey key(b_parent, b_index, b_ob);
+	ObjectKey key(b_parent, persistent_id, b_ob);
 
 	if(!light_map.sync(&light, b_ob, b_parent, key))
 		return;
@@ -196,23 +196,24 @@ void BlenderSync::sync_background_light()
 
 /* Object */
 
-void BlenderSync::sync_object(BL::Object b_parent, int b_index, BL::DupliObject b_dupli_ob, Transform& tfm, uint layer_flag, int motion, int particle_id)
+Object *BlenderSync::sync_object(BL::Object b_parent, int persistent_id[OBJECT_PERSISTENT_ID_SIZE], BL::DupliObject b_dupli_ob, Transform& tfm, uint layer_flag, int motion)
 {
 	BL::Object b_ob = (b_dupli_ob ? b_dupli_ob.object() : b_parent);
 	
 	/* light is handled separately */
 	if(object_is_light(b_ob)) {
 		if(!motion)
-			sync_light(b_parent, b_index, b_ob, tfm);
-		return;
+			sync_light(b_parent, persistent_id, b_ob, tfm);
+
+		return NULL;
 	}
 
 	/* only interested in object that we can create meshes from */
 	if(!object_is_mesh(b_ob))
-		return;
+		return NULL;
 
 	/* key to lookup object */
-	ObjectKey key(b_parent, b_index, b_ob);
+	ObjectKey key(b_parent, persistent_id, b_ob);
 	Object *object;
 
 	/* motion vector case */
@@ -234,7 +235,7 @@ void BlenderSync::sync_object(BL::Object b_parent, int b_index, BL::DupliObject
 				sync_mesh_motion(b_ob, object->mesh, motion);
 		}
 
-		return;
+		return object;
 	}
 
 	/* test if we need to sync */
@@ -248,13 +249,14 @@ void BlenderSync::sync_object(BL::Object b_parent, int b_index, BL::DupliObject
 	/* mesh sync */
 	object->mesh = sync_mesh(b_ob, object_updated);
 
+	/* sspecial case not tracked by object update flags */
 	if(use_holdout != object->use_holdout) {
 		object->use_holdout = use_holdout;
 		scene->object_manager->tag_update(scene);
 	}
 
-	/* object sync */
-	/* transform comparison should not be needed, but duplis don't work perfect
+	/* object sync
+	 * transform comparison should not be needed, but duplis don't work perfect
 	 * in the depsgraph and may not signal changes, so this is a workaround */
 	if(object_updated || (object->mesh && object->mesh->need_update) || tfm != object->tfm) {
 		object->name = b_ob.name().c_str();
@@ -264,7 +266,10 @@ void BlenderSync::sync_object(BL::Object b_parent, int b_index, BL::DupliObject
 		object->motion.post = tfm;
 		object->use_motion = false;
 
-		object->random_id = hash_int_2d(hash_string(object->name.c_str()), b_index);
+		object->random_id = hash_string(object->name.c_str());
+		if(persistent_id)
+			for(int i = 0; i < OBJECT_PERSISTENT_ID_SIZE; i++)
+				object->random_id = hash_int_2d(object->random_id, persistent_id[i]);
 
 		/* visibility flags for both parent */
 		object->visibility = object_ray_visibility(b_ob) & PATH_RAY_ALL;
@@ -289,10 +294,10 @@ void BlenderSync::sync_object(BL::Object b_parent, int b_index, BL::DupliObject
 			object->dupli_uv = make_float2(0.0f, 0.0f);
 		}
 
-		object->particle_id = particle_id;
-
 		object->tag_update(scene);
 	}
+
+	return object;
 }
 
 /* Object Loop */
@@ -314,7 +319,9 @@ void BlenderSync::sync_objects(BL::SpaceView3D b_v3d, int motion)
 	/* object loop */
 	BL::Scene::objects_iterator b_ob;
 	BL::Scene b_sce = b_scene;
-	int particle_offset = 1;	/* first particle is dummy for regular, non-instanced objects */
+
+	/* global particle index counter */
+	int particle_id = 1;
 
 	bool cancel = false;
 
@@ -327,16 +334,14 @@ void BlenderSync::sync_objects(BL::SpaceView3D b_v3d, int motion)
 			if(!hide) {
 				progress.set_sync_status("Synchronizing object", (*b_ob).name());
 
-				int num_particles = object_count_particles(*b_ob);
-
 				if(b_ob->is_duplicator()) {
-					hide = true; /* duplicators hidden by default */
+					/* duplicators hidden by default */
+					hide = true;
 
 					/* dupli objects */
 					b_ob->dupli_list_create(b_scene, 2);
 
 					BL::Object::dupli_list_iterator b_dup;
-					int b_index = 0;
 
 					for(b_ob->dupli_list.begin(b_dup); b_dup != b_ob->dupli_list.end(); ++b_dup) {
 						Transform tfm = get_transform(b_dup->matrix());
@@ -345,7 +350,8 @@ void BlenderSync::sync_objects(BL::SpaceView3D b_v3d, int motion)
 						bool emitter_hide = false;
 
 						if(b_dup_ob.is_duplicator()) {
-							emitter_hide = true;	/* duplicators hidden by default */
+							/* duplicators hidden by default */
+							emitter_hide = true;
 							
 							/* check if we should render or hide particle emitter */
 							BL::Object::particle_systems_iterator b_psys;
@@ -355,21 +361,34 @@ void BlenderSync::sync_objects(BL::SpaceView3D b_v3d, int motion)
 						}
 
 						if(!(b_dup->hide() || dup_hide || emitter_hide)) {
-							sync_object(*b_ob, b_index, *b_dup, tfm, ob_layer, motion, b_dup->particle_index() + particle_offset);
+							/* the persistent_id allows us to match dupli objects
+							 * between frames and updates */
+							BL::Array<int, OBJECT_PERSISTENT_ID_SIZE> persistent_id = b_dup->persistent_id();
+
+							/* sync object and mesh or light data */
+							Object *object = sync_object(*b_ob, persistent_id.data, *b_dup, tfm, ob_layer, motion);
+
+							/* sync possible particle data, note particle_id
+							 * starts counting at 1, first is dummy particle */
+							if(!motion && object && sync_dupli_particle(*b_ob, *b_dup, object)) {
+								if(particle_id != object->particle_id) {
+									object->particle_id = particle_id;
+									scene->object_manager->tag_update(scene);
+								}
+
+								particle_id++;
+							}
+
 						}
-						
-						++b_index;
 					}
 
 					b_ob->dupli_list_clear();
 				}
 
-				/* sync particles and check if we should render or hide particle emitter */
+				/* check if we should render or hide particle emitter */
 				BL::Object::particle_systems_iterator b_psys;
-				for(b_ob->particle_systems.begin(b_psys); b_psys != b_ob->particle_systems.end(); ++b_psys) {
-					if(!motion)
-						sync_particles(*b_ob, *b_psys);
 
+				for(b_ob->particle_systems.begin(b_psys); b_psys != b_ob->particle_systems.end(); ++b_psys) {
 					if(b_psys->settings().use_render_emitter())
 						hide = false;
 				}
@@ -377,10 +396,8 @@ void BlenderSync::sync_objects(BL::SpaceView3D b_v3d, int motion)
 				if(!hide) {
 					/* object itself */
 					Transform tfm = get_transform(b_ob->matrix_world());
-					sync_object(*b_ob, 0, PointerRNA_NULL, tfm, ob_layer, motion, 0);
+					sync_object(*b_ob, NULL, PointerRNA_NULL, tfm, ob_layer, motion);
 				}
-
-				particle_offset += num_particles;
 			}
 
 			cancel = progress.get_cancel();