Cycles: Support rendering objects from dupli-list

This commit extends the work from Dalai made around scene iterators to
support iterating into objects from dupli-lists.

Changes can be summarized as:

- Depsgraph iterator will hold pointer to an object which created current
  duplilist. It is available via `dupli_parent` field of the iterator.
  It is only set when duplilist is not NULL and guaranteed to be NULL
  for all other cases.

- Introduced new depsgraph.duplis collection which gives a more extended
  information about depsgraph iterator.  It is basically a collection on top
  of DEGObjectsIteratorData.

  It is used to provide access to such data as persistent ID, generated space
  and so on.

Things which still needs to be done/finished/clarified:

- Need to introduce some sort of `is_instance` boolean property which will
  indicate Python and C++ RNA that we are inside of dupli-list.

- Introduce a way to skip dupli-list for particular objects.

  So, for example, if we are culling object due to distance we can skip all
  objects it was duplicating.

- Introduce a way to skip particular duplicators.

  So we can skip iterating into particle system.

- Introduce some cleaner API for C side of operators to access all data such as
  persistent ID and friends.

  This way we wouldn't need de-reference iterator and could keep access to such
  data really abstract. Who knows how we'll be storing internal state of the
  operator in the future.

While there is still stuff to do, current state works and moves us in the proper
direction.

1 files changed, 34 insertions, 17 deletions

diff --git a/source/blender/depsgraph/intern/depsgraph_query.cc b/source/blender/depsgraph/intern/depsgraph_query.cc
index d889dccfede..0661f24fb7b 100644
--- a/source/blender/depsgraph/intern/depsgraph_query.cc
+++ b/source/blender/depsgraph/intern/depsgraph_query.cc
@@ -104,27 +104,34 @@ Object *DEG_get_object(Depsgraph * /*depsgraph*/, Object *ob)
 
 void DEG_objects_iterator_begin(BLI_Iterator *iter, DEGObjectsIteratorData *data)
 {
-	SceneLayer *scene_layer;
 	Depsgraph *graph = data->graph;
+	SceneLayer *scene_layer = DEG_get_scene_layer(graph);
 
 	iter->data = data;
 	iter->valid = true;
 
-	/* TODO: Make it in-place initilization of evaluation context. */
-	data->eval_ctx = DEG_evaluation_context_new(DAG_EVAL_RENDER);
 	data->scene = DEG_get_scene(graph);
-	scene_layer = DEG_get_scene_layer(graph);
-	data->base_flag = ~BASE_FLUSH_FLAGS;
+	/* TODO(sergey): Make it in-place initilization of evaluation context. */
+	data->eval_ctx = DEG_evaluation_context_new(DAG_EVAL_RENDER);
 
+	/* TODO(sergey): It's really confusing to store pointer to a local data. */
 	Base base = {(Base *)scene_layer->object_bases.first, NULL};
 	data->base = &base;
+
+	data->base_flag = ~(BASE_FLUSH_FLAGS);
+
+	data->dupli_parent = NULL;
+	data->dupli_list = NULL;
+	data->dupli_object_next = NULL;
+	data->dupli_object_current = NULL;
+
 	DEG_objects_iterator_next(iter);
 }
 
 /**
  * Temporary function to flush depsgraph until we get copy on write (CoW)
  */
-static void deg_flush_data(Object *ob, Base *base, const int flag)
+static void deg_flush_base_flags_and_settings(Object *ob, Base *base, const int flag)
 {
 	ob->base_flag = (base->flag | BASE_FLUSH_FLAGS) & flag;
 	ob->base_collection_properties = base->collection_properties;
@@ -134,13 +141,15 @@ static void deg_flush_data(Object *ob, Base *base, const int flag)
 static bool deg_objects_dupli_iterator_next(BLI_Iterator *iter)
 {
 	DEGObjectsIteratorData *data = (DEGObjectsIteratorData *)iter->data;
-	while (data->dupli_object) {
-		DupliObject *dob = data->dupli_object;
+	while (data->dupli_object_next != NULL) {
+		DupliObject *dob = data->dupli_object_next;
 		Object *obd = dob->ob;
 
-		data->dupli_object = data->dupli_object->next;
+		data->dupli_object_next = data->dupli_object_next->next;
 
-		/* Group duplis need to set ob matrices correct, for deform. so no_draw is part handled. */
+		/* Group duplis need to set ob matrices correct, for deform. so no_draw
+		 * is part handled.
+		 */
 		if ((obd->transflag & OB_RENDER_DUPLI) == 0 && dob->no_draw) {
 			continue;
 		}
@@ -149,11 +158,15 @@ static bool deg_objects_dupli_iterator_next(BLI_Iterator *iter)
 			continue;
 		}
 
+		data->dupli_object_current = dob;
+
 		/* Temporary object to evaluate. */
 		data->temp_dupli_object = *dob->ob;
 		copy_m4_m4(data->temp_dupli_object.obmat, dob->mat);
 
-		deg_flush_data(&data->temp_dupli_object, data->base, data->base_flag | BASE_FROMDUPLI);
+		deg_flush_base_flags_and_settings(&data->temp_dupli_object,
+		                                  data->base,
+		                                  data->base_flag | BASE_FROMDUPLI);
 		iter->current = &data->temp_dupli_object;
 		return true;
 	}
@@ -172,14 +185,15 @@ void DEG_objects_iterator_next(BLI_Iterator *iter)
 		}
 		else {
 			free_object_duplilist(data->dupli_list);
+			data->dupli_parent = NULL;
 			data->dupli_list = NULL;
-			data->dupli_object = NULL;
+			data->dupli_object_next = NULL;
+			data->dupli_object_current = NULL;
 		}
 	}
 
 	base = data->base->next;
-
-	while (base) {
+	while (base != NULL) {
 		if ((base->flag & BASE_VISIBLED) != 0) {
 			Object *ob = DEG_get_object(data->graph, base->object);
 			iter->current = ob;
@@ -191,15 +205,17 @@ void DEG_objects_iterator_next(BLI_Iterator *iter)
 			BLI_assert(!BLI_listbase_is_empty(&base->collection_properties->data.group));
 
 			/* Flushing depsgraph data. */
-			deg_flush_data(ob, base, data->base_flag);
+			deg_flush_base_flags_and_settings(ob,
+			                                  base,
+			                                  data->base_flag);
 
 			if ((data->flag & DEG_OBJECT_ITER_FLAG_DUPLI) && (ob->transflag & OB_DUPLI)) {
+				data->dupli_parent = ob;
 				data->dupli_list = object_duplilist(data->eval_ctx, data->scene, ob);
-				data->dupli_object = (DupliObject *)data->dupli_list->first;
+				data->dupli_object_next = (DupliObject *)data->dupli_list->first;
 			}
 			return;
 		}
-
 		base = base->next;
 	}
 
@@ -212,6 +228,7 @@ void DEG_objects_iterator_next(BLI_Iterator *iter)
 		/* For the sets we use the layer used for rendering. */
 		scene_layer = BKE_scene_layer_render_active(data->scene);
 
+		/* TODO(sergey): It's really confusing to store pointer to a local data. */
 		Base base = {(Base *)scene_layer->object_bases.first, NULL};
 		data->base = &base;
 		DEG_objects_iterator_next(iter);