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 technically a regression in 2.79a-RC as well, so would need to
backport this fix to the branch after extra testing is done here in the
studio.

3 files changed, 110 insertions, 49 deletions

diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc b/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
index 8d20a671202..1d18d6def8d 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
@@ -661,32 +661,40 @@ void DepsgraphNodeBuilder::build_particles(Object *object)
 	 *     blackbox evaluation step for one particle system referenced by
 	 *     the particle systems stack. All dependencies link to this operation.
 	 */
-
-	/* component for all particle systems */
+	/* Component for all particle systems. */
 	ComponentDepsNode *psys_comp =
 	        add_component_node(&object->id, DEG_NODE_TYPE_EVAL_PARTICLES);
-
 	add_operation_node(psys_comp,
 	                   function_bind(BKE_particle_system_eval_init,
 	                                 _1,
 	                                 scene_,
 	                                 object),
 	                   DEG_OPCODE_PARTICLE_SYSTEM_EVAL_INIT);
-
-	/* particle systems */
+	/* Build all particle systems. */
 	BLI_LISTBASE_FOREACH (ParticleSystem *, psys, &object->particlesystem) {
 		ParticleSettings *part = psys->part;
-
-		/* particle settings */
+		/* Particle settings. */
 		// XXX: what if this is used more than once!
 		build_animdata(&part->id);
-
-		/* this particle system */
+		/* This particle system evaluation. */
 		// TODO: for now, this will just be a placeholder "ubereval" node
 		add_operation_node(psys_comp,
 		                   NULL,
 		                   DEG_OPCODE_PARTICLE_SYSTEM_EVAL,
 		                   psys->name);
+		/* Visualization of particle system. */
+		switch (part->ren_as) {
+			case PART_DRAW_OB:
+				if (part->dup_ob != NULL) {
+					build_object(NULL, part->dup_ob);
+				}
+				break;
+			case PART_DRAW_GR:
+				if (part->dup_group != NULL) {
+					build_group(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 85ea2c0a8e4..c30d3fecdd5 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
@@ -193,6 +193,7 @@ static bool particle_system_depends_on_time(ParticleSystem *psys)
 
 static bool object_particles_depends_on_time(Object *object)
 {
+	return true;
 	BLI_LISTBASE_FOREACH (ParticleSystem *, psys, &object->particlesystem) {
 		if (particle_system_depends_on_time(psys)) {
 			return true;
@@ -426,15 +427,17 @@ void DepsgraphRelationBuilder::build_group(Object *object, Group *group)
 {
 	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);
 	BLI_LISTBASE_FOREACH (GroupObject *, go, &group->gobject) {
 		if (!group_done) {
 			build_object(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;
 }
@@ -1360,67 +1363,92 @@ void DepsgraphRelationBuilder::build_particles(Object *object)
 	                           DEG_NODE_TYPE_EVAL_PARTICLES,
 	                           DEG_OPCODE_PARTICLE_SYSTEM_EVAL_INIT);
 
-	/* particle systems */
+	/* Particle systems. */
 	BLI_LISTBASE_FOREACH (ParticleSystem *, psys, &object->particlesystem) {
 		ParticleSettings *part = psys->part;
-
-		/* particle settings */
+		/* Animation of particle settings, */
 		build_animdata(&part->id);
-
-		/* this particle system */
-		OperationKey psys_key(&object->id, DEG_NODE_TYPE_EVAL_PARTICLES, DEG_OPCODE_PARTICLE_SYSTEM_EVAL, psys->name);
-
-		/* XXX: if particle system is later re-enabled, we must do full rebuild? */
-		if (!psys_check_enabled(object, psys, G.is_rendering))
-			continue;
-
+		/* This particle system. */
+		OperationKey psys_key(&object->id,
+		                      DEG_NODE_TYPE_EVAL_PARTICLES,
+		                      DEG_OPCODE_PARTICLE_SYSTEM_EVAL,
+		                      psys->name);
 		add_relation(eval_init_key, psys_key, "Init -> PSys");
-
 		/* TODO(sergey): Currently particle update is just a placeholder,
 		 * hook it to the ubereval node so particle system is getting updated
 		 * on playback.
 		 */
 		add_relation(psys_key, obdata_ubereval_key, "PSys -> UberEval");
-
-		/* collisions */
+		/* Collisions */
 		if (part->type != PART_HAIR) {
-			add_collision_relations(psys_key, scene_, object, part->collision_group, object->lay, true, "Particle Collision");
+			add_collision_relations(psys_key,
+			                        scene_,
+			                        object,
+			                        part->collision_group,
+			                        object->lay,
+			                        true,
+			                        "Particle Collision");
 		}
-		else if ((psys->flag & PSYS_HAIR_DYNAMICS) && psys->clmd && psys->clmd->coll_parms) {
-			add_collision_relations(psys_key, scene_, object, psys->clmd->coll_parms->group, object->lay | scene_->lay, true, "Hair Collision");
+		else if ((psys->flag & PSYS_HAIR_DYNAMICS) &&
+		         psys->clmd && psys->clmd->coll_parms)
+		{
+			add_collision_relations(psys_key,
+			                        scene_,
+			                        object,
+			                        psys->clmd->coll_parms->group,
+			                        object->lay | scene_->lay,
+			                        true,
+			                        "Hair Collision");
 		}
-
-		/* effectors */
-		add_forcefield_relations(psys_key, scene_, object, psys, part->effector_weights, part->type == PART_HAIR, "Particle Field");
-
-		/* boids */
+		/* Effectors. */
+		add_forcefield_relations(psys_key,
+		                         scene_,
+		                         object,
+		                         psys,
+		                         part->effector_weights,
+		                         part->type == PART_HAIR,
+		                         "Particle Field");
+		/* Boids. */
 		if (part->boids) {
 			BLI_LISTBASE_FOREACH (BoidState *, state, &part->boids->states) {
 				BLI_LISTBASE_FOREACH (BoidRule *, rule, &state->rules) {
 					Object *ruleob = NULL;
-					if (rule->type == eBoidRuleType_Avoid)
+					if (rule->type == eBoidRuleType_Avoid) {
 						ruleob = ((BoidRuleGoalAvoid *)rule)->ob;
-					else if (rule->type == eBoidRuleType_FollowLeader)
+					}
+					else if (rule->type == eBoidRuleType_FollowLeader) {
 						ruleob = ((BoidRuleFollowLeader *)rule)->ob;
-
+					}
 					if (ruleob) {
-						ComponentKey ruleob_key(&ruleob->id, DEG_NODE_TYPE_TRANSFORM);
+						ComponentKey ruleob_key(&ruleob->id,
+						                        DEG_NODE_TYPE_TRANSFORM);
 						add_relation(ruleob_key, psys_key, "Boid Rule");
 					}
 				}
 			}
 		}
 
-		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(obdata_ubereval_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(part->dup_ob);
+					/* Build relation for the particle visualization. */
+					build_particles_visualization_object(object,
+					                                     psys,
+					                                     part->dup_ob);
+				}
+				break;
+			case PART_DRAW_GR:
+				if (part->dup_group != NULL) {
+					build_group(NULL, part->dup_group);
+					BLI_LISTBASE_FOREACH (GroupObject *, go, &part->dup_group->gobject) {
+						build_particles_visualization_object(object,
+						                                     psys,
+						                                     go->ob);
+					}
+				}
+				break;
 		}
 	}
 
@@ -1437,6 +1465,28 @@ void DepsgraphRelationBuilder::build_particles(Object *object)
 	// 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_PARTICLE_SYSTEM_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(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 aa55b9f66ae..aa8dc2a4982 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.h
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.h
@@ -66,11 +66,11 @@ struct bNodeTree;
 struct Object;
 struct bPoseChannel;
 struct bConstraint;
+struct ParticleSystem;
 struct Scene;
 struct Tex;
 struct World;
 struct EffectorWeights;
-struct ParticleSystem;
 
 struct PropertyRNA;
 
@@ -216,6 +216,9 @@ struct DepsgraphRelationBuilder
 	void build_world(World *world);
 	void build_rigidbody(Scene *scene);
 	void build_particles(Object *object);
+	void build_particles_visualization_object(Object *object,
+	                                          ParticleSystem *psys,
+	                                          Object *draw_object);
 	void build_cloth(Object *object, ModifierData *md);
 	void build_ik_pose(Object *object,
 	                   bPoseChannel *pchan,