Fix missing group duplicated by hair in render

Was happening when viewport visibility on the particle system is disabled.
This became an issue after c45afcf, but the actual issue goes a bit deeper
and the following aspects were involved:

- Relations builder for particle system was ignoring particle system if
  it's visibility is not enabled for viewport. This is something what
  shouldn't have been done -- depsgraph relations are supposed to be the
  same no matter if it's viewport or render.

- Relation builder was only dealing with duplication set to object, but
  was ignoring group duplication.

This is NOT a regression since 2.79, but a regression since 2.79a-rc1.

4 files changed, 91 insertions, 20 deletions

diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc b/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
index dfd43a4dd2e..539e96ae390 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
@@ -696,6 +696,19 @@ void DepsgraphNodeBuilder::build_particles(Scene *scene, Object *ob)
 		                   NULL,
 		                   DEG_OPCODE_PSYS_EVAL,
 		                   psys->name);
+		/* Visualization of particle system. */
+		switch (part->ren_as) {
+			case PART_DRAW_OB:
+				if (part->dup_ob != NULL) {
+					build_object(scene, NULL, part->dup_ob);
+				}
+				break;
+			case PART_DRAW_GR:
+				if (part->dup_group != NULL) {
+					build_group(scene, NULL, part->dup_group);
+				}
+				break;
+		}
 	}
 
 	/* pointcache */
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
index 525a718d03a..bfec2f0e3e3 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
@@ -419,15 +419,17 @@ void DepsgraphRelationBuilder::build_group(Main *bmain,
 {
 	ID *group_id = &group->id;
 	bool group_done = (group_id->tag & LIB_TAG_DOIT) != 0;
-	OperationKey object_local_transform_key(&object->id,
+	OperationKey object_local_transform_key(object != NULL ? &object->id : NULL,
 	                                        DEG_NODE_TYPE_TRANSFORM,
 	                                        DEG_OPCODE_TRANSFORM_LOCAL);
 	LINKLIST_FOREACH (GroupObject *, go, &group->gobject) {
 		if (!group_done) {
 			build_object(bmain, scene, go->ob);
 		}
-		ComponentKey dupli_transform_key(&go->ob->id, DEG_NODE_TYPE_TRANSFORM);
-		add_relation(dupli_transform_key, object_local_transform_key, "Dupligroup");
+		if (object != NULL) {
+			ComponentKey dupli_transform_key(&go->ob->id, DEG_NODE_TYPE_TRANSFORM);
+			add_relation(dupli_transform_key, object_local_transform_key, "Dupligroup");
+		}
 	}
 	group_id->tag |= LIB_TAG_DOIT;
 }
@@ -568,7 +570,7 @@ void DepsgraphRelationBuilder::build_object(Main *bmain, Scene *scene, Object *o
 
 	/* Particle systems. */
 	if (ob->particlesystem.first != NULL) {
-		build_particles(scene, ob);
+		build_particles(bmain, scene, ob);
 	}
 
 	/* Grease pencil. */
@@ -1272,7 +1274,7 @@ void DepsgraphRelationBuilder::build_rigidbody(Scene *scene)
 	}
 }
 
-void DepsgraphRelationBuilder::build_particles(Scene *scene, Object *ob)
+void DepsgraphRelationBuilder::build_particles(Main *bmain, Scene *scene, Object *ob)
 {
 	TimeSourceKey time_src_key;
 	OperationKey obdata_ubereval_key(&ob->id,
@@ -1292,10 +1294,6 @@ void DepsgraphRelationBuilder::build_particles(Scene *scene, Object *ob)
 		/* this particle system */
 		OperationKey psys_key(&ob->id, DEG_NODE_TYPE_EVAL_PARTICLES, DEG_OPCODE_PSYS_EVAL, psys->name);
 
-		/* XXX: if particle system is later re-enabled, we must do full rebuild? */
-		if (!psys_check_enabled(ob, psys, G.is_rendering))
-			continue;
-
 		add_relation(eval_init_key, psys_key, "Init -> PSys");
 
 		/* TODO(sergey): Currently particle update is just a placeholder,
@@ -1333,16 +1331,27 @@ void DepsgraphRelationBuilder::build_particles(Scene *scene, Object *ob)
 			}
 		}
 
-		if (part->ren_as == PART_DRAW_OB && part->dup_ob) {
-			ComponentKey dup_ob_key(&part->dup_ob->id, DEG_NODE_TYPE_TRANSFORM);
-			add_relation(dup_ob_key, psys_key, "Particle Object Visualization");
-			if (part->dup_ob->type == OB_MBALL) {
-				ComponentKey dup_geometry_key(&part->dup_ob->id,
-				                              DEG_NODE_TYPE_GEOMETRY);
-				add_relation(psys_key,
-				             dup_geometry_key,
-				             "Particle MBall Visualization");
-			}
+		switch (part->ren_as) {
+			case PART_DRAW_OB:
+				if (part->dup_ob != NULL) {
+					/* Make sure object's relations are all built.  */
+					build_object(bmain, scene, part->dup_ob);
+					/* Build relation for the particle visualization. */
+					build_particles_visualization_object(ob,
+					                                     psys,
+					                                     part->dup_ob);
+				}
+				break;
+			case PART_DRAW_GR:
+				if (part->dup_group != NULL) {
+					build_group(bmain, scene, NULL, part->dup_group);
+					LINKLIST_FOREACH (GroupObject *, go, &part->dup_group->gobject) {
+						build_particles_visualization_object(ob,
+						                                     psys,
+						                                     go->ob);
+					}
+				}
+				break;
 		}
 	}
 
@@ -1359,6 +1368,28 @@ void DepsgraphRelationBuilder::build_particles(Scene *scene, Object *ob)
 	// TODO...
 }
 
+void DepsgraphRelationBuilder::build_particles_visualization_object(
+        Object *object,
+        ParticleSystem *psys,
+        Object *draw_object)
+{
+	OperationKey psys_key(&object->id,
+	                      DEG_NODE_TYPE_EVAL_PARTICLES,
+	                      DEG_OPCODE_PSYS_EVAL,
+	                      psys->name);
+	OperationKey obdata_ubereval_key(&object->id,
+	                                 DEG_NODE_TYPE_GEOMETRY,
+	                                 DEG_OPCODE_GEOMETRY_UBEREVAL);
+	ComponentKey dup_ob_key(&draw_object->id, DEG_NODE_TYPE_TRANSFORM);
+	add_relation(dup_ob_key, psys_key, "Particle Object Visualization");
+	if (draw_object->type == OB_MBALL) {
+		ComponentKey dup_geometry_key(&draw_object->id, DEG_NODE_TYPE_GEOMETRY);
+		add_relation(obdata_ubereval_key,
+		             dup_geometry_key,
+		             "Particle MBall Visualization");
+	}
+}
+
 void DepsgraphRelationBuilder::build_cloth(Scene * /*scene*/,
                                            Object *object,
                                            ModifierData * /*md*/)
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.h b/source/blender/depsgraph/intern/builder/deg_builder_relations.h
index 02f8fc69070..2c3c530f41c 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.h
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.h
@@ -197,7 +197,10 @@ struct DepsgraphRelationBuilder
 	void build_driver(ID *id, FCurve *fcurve);
 	void build_world(World *world);
 	void build_rigidbody(Scene *scene);
-	void build_particles(Scene *scene, Object *ob);
+	void build_particles(Main *bmain, Scene *scene, Object *ob);
+	void build_particles_visualization_object(Object *object,
+	                                          ParticleSystem *psys,
+	                                          Object *draw_object);
 	void build_cloth(Scene *scene, Object *object, ModifierData *md);
 	void build_ik_pose(Object *ob,
 	                   bPoseChannel *pchan,
diff --git a/source/blender/render/intern/source/pipeline.c b/source/blender/render/intern/source/pipeline.c
index 9a924032143..9ed1520fa81 100644
--- a/source/blender/render/intern/source/pipeline.c
+++ b/source/blender/render/intern/source/pipeline.c
@@ -37,9 +37,11 @@
 #include <errno.h>
 
 #include "DNA_anim_types.h"
+#include "DNA_group_types.h"
 #include "DNA_image_types.h"
 #include "DNA_node_types.h"
 #include "DNA_object_types.h"
+#include "DNA_particle_types.h"
 #include "DNA_scene_types.h"
 #include "DNA_sequence_types.h"
 #include "DNA_userdef_types.h"
@@ -2059,6 +2061,28 @@ static void tag_dependend_objects_for_render(Scene *scene, int renderlay)
 							DAG_id_tag_update(&smd->target->id, OB_RECALC_DATA);
 						}
 					}
+					else if (md->type == eModifierType_ParticleSystem) {
+						ParticleSystemModifierData *psmd = (ParticleSystemModifierData *)md;
+						ParticleSystem *psys = psmd->psys;
+						ParticleSettings *part = psys->part;
+						switch (part->ren_as) {
+							case PART_DRAW_OB:
+								if (part->dup_ob != NULL) {
+									DAG_id_tag_update(&part->dup_ob->id, OB_RECALC_DATA);
+								}
+								break;
+							case PART_DRAW_GR:
+								if (part->dup_group != NULL) {
+									for (GroupObject *go = part->dup_group->gobject.first;
+									     go != NULL;
+									     go = go->next)
+									{
+										DAG_id_tag_update(&go->ob->id, OB_RECALC_DATA);
+									}
+								}
+								break;
+						}
+					}
 				}
 			}
 		}