Cycles: Add support for light groups

Light groups are a type of pass that only contains lighting from a subset of light sources.
They are created in the View layer, and light sources (lamps, objects with emissive materials
and/or the environment) can be assigned to a group.

Currently, each light group ends up generating its own version of the Combined pass.
In the future, additional types of passes (e.g. shadowcatcher) might be getting their own
per-lightgroup versions.

The lightgroup creation and assignment is not Cycles-specific, so Eevee or external render
engines could make use of it in the future.

Note that Lightgroups are identified by their name - therefore, the name of the Lightgroup
in the View Layer and the name that's set in an object's settings must match for it to be
included.
Currently, changing a Lightgroup's name does not update objects - this is planned for the
future, along with other features such as denoising for light groups and viewing them in
preview renders.

Original patch by Alex Fuller (@mistaed), with some polishing by Lukas Stockner (@lukasstockner97).

Differential Revision: https://developer.blender.org/D12871

source/blender/blenkernel/BKE_layer.h

@@ -8,6 +8,7 @@
 
 #include "BKE_collection.h"
 
+#include "DNA_layer_types.h"
 #include "DNA_listBase.h"
 
 #ifdef __cplusplus
@@ -581,6 +582,21 @@ bool BKE_view_layer_has_valid_aov(struct ViewLayer *view_layer);
 struct ViewLayer *BKE_view_layer_find_with_aov(struct Scene *scene,
                                                struct ViewLayerAOV *view_layer_aov);
 
+struct ViewLayerLightgroup *BKE_view_layer_add_lightgroup(struct ViewLayer *view_layer);
+void BKE_view_layer_remove_lightgroup(struct ViewLayer *view_layer,
+                                      struct ViewLayerLightgroup *lightgroup);
+void BKE_view_layer_set_active_lightgroup(struct ViewLayer *view_layer,
+                                          struct ViewLayerLightgroup *lightgroup);
+struct ViewLayer *BKE_view_layer_find_with_lightgroup(
+    struct Scene *scene, struct ViewLayerLightgroup *view_layer_lightgroup);
+void BKE_view_layer_rename_lightgroup(ViewLayer *view_layer,
+                                      ViewLayerLightgroup *lightgroup,
+                                      const char *name);
+
+void BKE_lightgroup_membership_get(struct LightgroupMembership *lgm, char *value);
+int BKE_lightgroup_membership_length(struct LightgroupMembership *lgm);
+void BKE_lightgroup_membership_set(struct LightgroupMembership **lgm, const char *value);
+
 #ifdef __cplusplus
 }
 #endif

source/blender/blenkernel/intern/layer.c

@@ -266,6 +266,8 @@ void BKE_view_layer_free_ex(ViewLayer *view_layer, const bool do_id_user)
   BLI_freelistN(&view_layer->drawdata);
   BLI_freelistN(&view_layer->aovs);
   view_layer->active_aov = NULL;
+  BLI_freelistN(&view_layer->lightgroups);
+  view_layer->active_lightgroup = NULL;
 
   MEM_SAFE_FREE(view_layer->stats);
 
@@ -428,6 +430,29 @@ static void layer_aov_copy_data(ViewLayer *view_layer_dst,
   }
 }
 
+static void layer_lightgroup_copy_data(ViewLayer *view_layer_dst,
+                                       const ViewLayer *view_layer_src,
+                                       ListBase *lightgroups_dst,
+                                       const ListBase *lightgroups_src)
+{
+  if (lightgroups_src != NULL) {
+    BLI_duplicatelist(lightgroups_dst, lightgroups_src);
+  }
+
+  ViewLayerLightgroup *lightgroup_dst = lightgroups_dst->first;
+  const ViewLayerLightgroup *lightgroup_src = lightgroups_src->first;
+
+  while (lightgroup_dst != NULL) {
+    BLI_assert(lightgroup_src);
+    if (lightgroup_src == view_layer_src->active_lightgroup) {
+      view_layer_dst->active_lightgroup = lightgroup_dst;
+    }
+
+    lightgroup_dst = lightgroup_dst->next;
+    lightgroup_src = lightgroup_src->next;
+  }
+}
+
 static void layer_collections_copy_data(ViewLayer *view_layer_dst,
                                         const ViewLayer *view_layer_src,
                                         ListBase *layer_collections_dst,
@@ -496,6 +521,10 @@ void BKE_view_layer_copy_data(Scene *scene_dst,
   layer_aov_copy_data(
       view_layer_dst, view_layer_src, &view_layer_dst->aovs, &view_layer_src->aovs);
 
+  BLI_listbase_clear(&view_layer_dst->lightgroups);
+  layer_lightgroup_copy_data(
+      view_layer_dst, view_layer_src, &view_layer_dst->lightgroups, &view_layer_src->lightgroups);
+
   if ((flag & LIB_ID_CREATE_NO_USER_REFCOUNT) == 0) {
     id_us_plus((ID *)view_layer_dst->mat_override);
   }
@@ -2256,6 +2285,9 @@ void BKE_view_layer_blend_write(BlendWriter *writer, ViewLayer *view_layer)
   LISTBASE_FOREACH (ViewLayerAOV *, aov, &view_layer->aovs) {
     BLO_write_struct(writer, ViewLayerAOV, aov);
   }
+  LISTBASE_FOREACH (ViewLayerLightgroup *, lightgroup, &view_layer->lightgroups) {
+    BLO_write_struct(writer, ViewLayerLightgroup, lightgroup);
+  }
   write_layer_collections(writer, &view_layer->layer_collections);
 }
 
@@ -2294,6 +2326,9 @@ void BKE_view_layer_blend_read_data(BlendDataReader *reader, ViewLayer *view_lay
   BLO_read_list(reader, &view_layer->aovs);
   BLO_read_data_address(reader, &view_layer->active_aov);
 
+  BLO_read_list(reader, &view_layer->lightgroups);
+  BLO_read_data_address(reader, &view_layer->active_lightgroup);
+
   BLI_listbase_clear(&view_layer->drawdata);
   view_layer->object_bases_array = NULL;
   view_layer->object_bases_hash = NULL;
@@ -2471,4 +2506,117 @@ ViewLayer *BKE_view_layer_find_with_aov(struct Scene *scene, struct ViewLayerAOV
   return NULL;
 }
 
+/* -------------------------------------------------------------------- */
+/** \name Light Groups
+ * \{ */
+
+static void viewlayer_lightgroup_make_name_unique(ViewLayer *view_layer,
+                                                  ViewLayerLightgroup *lightgroup)
+{
+  /* Don't allow dots, it's incompatible with OpenEXR convention to store channels
+   * as "layer.pass.channel". */
+  BLI_str_replace_char(lightgroup->name, '.', '_');
+  BLI_uniquename(&view_layer->lightgroups,
+                 lightgroup,
+                 DATA_("Lightgroup"),
+                 '_',
+                 offsetof(ViewLayerLightgroup, name),
+                 sizeof(lightgroup->name));
+}
+
+static void viewlayer_lightgroup_active_set(ViewLayer *view_layer, ViewLayerLightgroup *lightgroup)
+{
+  if (lightgroup != NULL) {
+    BLI_assert(BLI_findindex(&view_layer->lightgroups, lightgroup) != -1);
+    view_layer->active_lightgroup = lightgroup;
+  }
+  else {
+    view_layer->active_lightgroup = NULL;
+  }
+}
+
+struct ViewLayerLightgroup *BKE_view_layer_add_lightgroup(struct ViewLayer *view_layer)
+{
+  ViewLayerLightgroup *lightgroup;
+  lightgroup = MEM_callocN(sizeof(ViewLayerLightgroup), __func__);
+  BLI_strncpy(lightgroup->name, DATA_("Lightgroup"), sizeof(lightgroup->name));
+  BLI_addtail(&view_layer->lightgroups, lightgroup);
+  viewlayer_lightgroup_active_set(view_layer, lightgroup);
+  viewlayer_lightgroup_make_name_unique(view_layer, lightgroup);
+  return lightgroup;
+}
+
+void BKE_view_layer_remove_lightgroup(ViewLayer *view_layer, ViewLayerLightgroup *lightgroup)
+{
+  BLI_assert(BLI_findindex(&view_layer->lightgroups, lightgroup) != -1);
+  BLI_assert(lightgroup != NULL);
+  if (view_layer->active_lightgroup == lightgroup) {
+    if (lightgroup->next) {
+      viewlayer_lightgroup_active_set(view_layer, lightgroup->next);
+    }
+    else {
+      viewlayer_lightgroup_active_set(view_layer, lightgroup->prev);
+    }
+  }
+  BLI_freelinkN(&view_layer->lightgroups, lightgroup);
+}
+
+void BKE_view_layer_set_active_lightgroup(ViewLayer *view_layer, ViewLayerLightgroup *lightgroup)
+{
+  viewlayer_lightgroup_active_set(view_layer, lightgroup);
+}
+
+ViewLayer *BKE_view_layer_find_with_lightgroup(struct Scene *scene,
+                                               struct ViewLayerLightgroup *lightgroup)
+{
+  LISTBASE_FOREACH (ViewLayer *, view_layer, &scene->view_layers) {
+    if (BLI_findindex(&view_layer->lightgroups, lightgroup) != -1) {
+      return view_layer;
+    }
+  }
+  return NULL;
+}
+
+void BKE_view_layer_rename_lightgroup(ViewLayer *view_layer,
+                                      ViewLayerLightgroup *lightgroup,
+                                      const char *name)
+{
+  BLI_strncpy_utf8(lightgroup->name, name, sizeof(lightgroup->name));
+  viewlayer_lightgroup_make_name_unique(view_layer, lightgroup);
+}
+
+void BKE_lightgroup_membership_get(struct LightgroupMembership *lgm, char *name)
+{
+  if (lgm != NULL) {
+    BLI_strncpy(name, lgm->name, sizeof(lgm->name));
+  }
+  else {
+    name[0] = '\0';
+  }
+}
+
+int BKE_lightgroup_membership_length(struct LightgroupMembership *lgm)
+{
+  if (lgm != NULL) {
+    return strlen(lgm->name);
+  }
+  return 0;
+}
+
+void BKE_lightgroup_membership_set(struct LightgroupMembership **lgm, const char *name)
+{
+  if (name[0] != '\0') {
+    if (*lgm == NULL) {
+      *lgm = MEM_callocN(sizeof(LightgroupMembership), __func__);
+    }
+    BLI_strncpy((*lgm)->name, name, sizeof((*lgm)->name));
+  }
+  else {
+    if (*lgm != NULL) {
+      MEM_freeN(*lgm);
+      *lgm = NULL;
+    }
+  }
+}
+
 /** \} */

source/blender/blenkernel/intern/object.cc

@@ -260,6 +260,10 @@ static void object_copy_data(Main *bmain, ID *id_dst, const ID *id_src, const in
   else {
     ob_dst->preview = nullptr;
   }
+
+  if (ob_src->lightgroup) {
+    ob_dst->lightgroup = (LightgroupMembership *)MEM_dupallocN(ob_src->lightgroup);
+  }
 }
 
 static void object_free_data(ID *id)
@@ -310,6 +314,8 @@ static void object_free_data(ID *id)
   }
 
   BKE_previewimg_free(&ob->preview);
+
+  MEM_SAFE_FREE(ob->lightgroup);
 }
 
 static void library_foreach_modifiersForeachIDLink(void *user_data,
@@ -584,6 +590,10 @@ static void object_blend_write(BlendWriter *writer, ID *id, const void *id_addre
   BLO_write_struct_list(writer, LinkData, &ob->pc_ids);
 
   BKE_previewimg_blend_write(writer, ob->preview);
+
+  if (ob->lightgroup) {
+    BLO_write_struct(writer, LightgroupMembership, ob->lightgroup);
+  }
 }
 
 /* XXX deprecated - old animation system */
@@ -800,6 +810,8 @@ static void object_blend_read_data(BlendDataReader *reader, ID *id)
 
   BLO_read_data_address(reader, &ob->preview);
   BKE_previewimg_blend_read(reader, ob->preview);
+
+  BLO_read_data_address(reader, &ob->lightgroup);
 }
 
 /* XXX deprecated - old animation system */

source/blender/blenkernel/intern/world.c

@@ -59,6 +59,8 @@ static void world_free_data(ID *id)
 
   BKE_icon_id_delete((struct ID *)wrld);
   BKE_previewimg_free(&wrld->preview);
+
+  MEM_SAFE_FREE(wrld->lightgroup);
 }
 
 static void world_init_data(ID *id)
@@ -107,6 +109,10 @@ static void world_copy_data(Main *bmain, ID *id_dst, const ID *id_src, const int
   else {
     wrld_dst->preview = NULL;
   }
+
+  if (wrld_src->lightgroup) {
+    wrld_dst->lightgroup = (LightgroupMembership *)MEM_dupallocN(wrld_src->lightgroup);
+  }
 }
 
 static void world_foreach_id(ID *id, LibraryForeachIDData *data)
@@ -142,6 +148,10 @@ static void world_blend_write(BlendWriter *writer, ID *id, const void *id_addres
   }
 
   BKE_previewimg_blend_write(writer, wrld->preview);
+
+  if (wrld->lightgroup) {
+    BLO_write_struct(writer, LightgroupMembership, wrld->lightgroup);
+  }
 }
 
 static void world_blend_read_data(BlendDataReader *reader, ID *id)
@@ -153,6 +163,8 @@ static void world_blend_read_data(BlendDataReader *reader, ID *id)
   BLO_read_data_address(reader, &wrld->preview);
   BKE_previewimg_blend_read(reader, wrld->preview);
   BLI_listbase_clear(&wrld->gpumaterial);
+
+  BLO_read_data_address(reader, &wrld->lightgroup);
 }
 
 static void world_blend_read_lib(BlendLibReader *reader, ID *id)

source/blender/editors/render/render_intern.hh

@@ -33,6 +33,8 @@ void SCENE_OT_view_layer_add(struct wmOperatorType *ot);
 void SCENE_OT_view_layer_remove(struct wmOperatorType *ot);
 void SCENE_OT_view_layer_add_aov(struct wmOperatorType *ot);
 void SCENE_OT_view_layer_remove_aov(struct wmOperatorType *ot);
+void SCENE_OT_view_layer_add_lightgroup(struct wmOperatorType *ot);
+void SCENE_OT_view_layer_remove_lightgroup(struct wmOperatorType *ot);
 
 void SCENE_OT_light_cache_bake(struct wmOperatorType *ot);
 void SCENE_OT_light_cache_free(struct wmOperatorType *ot);

source/blender/editors/render/render_ops.cc

@@ -39,6 +39,8 @@ void ED_operatortypes_render()
   WM_operatortype_append(SCENE_OT_view_layer_remove);
   WM_operatortype_append(SCENE_OT_view_layer_add_aov);
   WM_operatortype_append(SCENE_OT_view_layer_remove_aov);
+  WM_operatortype_append(SCENE_OT_view_layer_add_lightgroup);
+  WM_operatortype_append(SCENE_OT_view_layer_remove_lightgroup);
 
   WM_operatortype_append(SCENE_OT_render_view_add);
   WM_operatortype_append(SCENE_OT_render_view_remove);

source/blender/editors/render/render_shading.cc

@@ -1114,6 +1114,86 @@ void SCENE_OT_view_layer_remove_aov(wmOperatorType *ot)
 
 /** \} */
 
+/* -------------------------------------------------------------------- */
+/** \name View Layer Add Lightgroup Operator
+ * \{ */
+
+static int view_layer_add_lightgroup_exec(bContext *C, wmOperator *UNUSED(op))
+{
+  Scene *scene = CTX_data_scene(C);
+  ViewLayer *view_layer = CTX_data_view_layer(C);
+
+  BKE_view_layer_add_lightgroup(view_layer);
+
+  if (scene->nodetree) {
+    ntreeCompositUpdateRLayers(scene->nodetree);
+  }
+
+  DEG_id_tag_update(&scene->id, 0);
+  DEG_relations_tag_update(CTX_data_main(C));
+  WM_event_add_notifier(C, NC_SCENE | ND_LAYER, scene);
+
+  return OPERATOR_FINISHED;
+}
+
+void SCENE_OT_view_layer_add_lightgroup(wmOperatorType *ot)
+{
+  /* identifiers */
+  ot->name = "Add Lightgroup";
+  ot->idname = "SCENE_OT_view_layer_add_lightgroup";
+  ot->description = "Add a Light Group";
+
+  /* api callbacks */
+  ot->exec = view_layer_add_lightgroup_exec;
+
+  /* flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_INTERNAL;
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name View Layer Remove Lightgroup Operator
+ * \{ */
+
+static int view_layer_remove_lightgroup_exec(bContext *C, wmOperator *UNUSED(op))
+{
+  Scene *scene = CTX_data_scene(C);
+  ViewLayer *view_layer = CTX_data_view_layer(C);
+
+  if (view_layer->active_lightgroup == nullptr) {
+    return OPERATOR_FINISHED;
+  }
+
+  BKE_view_layer_remove_lightgroup(view_layer, view_layer->active_lightgroup);
+
+  if (scene->nodetree) {
+    ntreeCompositUpdateRLayers(scene->nodetree);
+  }
+
+  DEG_id_tag_update(&scene->id, 0);
+  DEG_relations_tag_update(CTX_data_main(C));
+  WM_event_add_notifier(C, NC_SCENE | ND_LAYER, scene);
+
+  return OPERATOR_FINISHED;
+}
+
+void SCENE_OT_view_layer_remove_lightgroup(wmOperatorType *ot)
+{
+  /* identifiers */
+  ot->name = "Remove Lightgroup";
+  ot->idname = "SCENE_OT_view_layer_remove_lightgroup";
+  ot->description = "Remove Active Lightgroup";
+
+  /* api callbacks */
+  ot->exec = view_layer_remove_lightgroup_exec;
+
+  /* flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_INTERNAL;
+}
+
+/** \} */
+
 /* -------------------------------------------------------------------- */
 /** \name Light Cache Bake Operator
  * \{ */

source/blender/makesdna/DNA_layer_types.h

@@ -124,6 +124,21 @@ typedef struct ViewLayerAOV {
    * matches `eViewLayerAOVType` */
   int type;
 } ViewLayerAOV;
+
+/* Lightgroup Renderpass definition. */
+typedef struct ViewLayerLightgroup {
+  struct ViewLayerLightgroup *next, *prev;
+
+  /* Name of the Lightgroup */
+  char name[64];
+} ViewLayerLightgroup;
+
+/* Lightgroup membership information. */
+typedef struct LightgroupMembership {
+  /* Name of the Lightgroup */
+  char name[64];
+} LightgroupMembership;
+
 typedef struct ViewLayer {
   struct ViewLayer *next, *prev;
   /** MAX_NAME. */
@@ -164,6 +179,10 @@ typedef struct ViewLayer {
   ListBase aovs;
   ViewLayerAOV *active_aov;
 
+  /* List containing the 'ViewLayerLightgroup`s */
+  ListBase lightgroups;
+  ViewLayerLightgroup *active_lightgroup;
+
   /* Runtime data */
   /** ViewLayerEngineData. */
   ListBase drawdata;

source/blender/makesdna/DNA_object_types.h

@@ -31,6 +31,7 @@ struct Curve;
 struct FluidsimSettings;
 struct GeometrySet;
 struct Ipo;
+struct LightgroupMembership;
 struct Material;
 struct Mesh;
 struct Object;
@@ -434,8 +435,10 @@ typedef struct Object {
 
   ObjectLineArt lineart;
 
+  /** Lightgroup membership information. */
+  struct LightgroupMembership *lightgroup;
+
   /** Runtime evaluation data (keep last). */
-  void *_pad9;
   Object_Runtime runtime;
 } Object;
 

source/blender/makesdna/DNA_world_types.h

@@ -16,6 +16,7 @@ extern "C" {
 
 struct AnimData;
 struct Ipo;
+struct LightgroupMembership;
 struct bNodeTree;
 
 #ifndef MAX_MTEX
@@ -70,6 +71,9 @@ typedef struct World {
   /* nodes */
   struct bNodeTree *nodetree;
 
+  /* Lightgroup membership information. */
+  struct LightgroupMembership *lightgroup;
+
   /** Runtime. */
   ListBase gpumaterial;
 } World;

source/blender/makesrna/intern/rna_internal.h

@@ -355,6 +355,10 @@ void rna_ViewLayer_active_aov_index_range(
     PointerRNA *ptr, int *min, int *max, int *softmin, int *softmax);
 int rna_ViewLayer_active_aov_index_get(PointerRNA *ptr);
 void rna_ViewLayer_active_aov_index_set(PointerRNA *ptr, int value);
+void rna_ViewLayer_active_lightgroup_index_range(
+    PointerRNA *ptr, int *min, int *max, int *softmin, int *softmax);
+int rna_ViewLayer_active_lightgroup_index_get(PointerRNA *ptr);
+void rna_ViewLayer_active_lightgroup_index_set(PointerRNA *ptr, int value);
 /**
  *  Set `r_rna_path` with the base view-layer path.
  *  `rna_path_buffer_size` should be at least `sizeof(ViewLayer.name) * 3`.

source/blender/makesrna/intern/rna_object.c

@@ -2292,6 +2292,21 @@ static int rna_Object_mesh_symmetry_yz_editable(PointerRNA *ptr, const char **UN
   return PROP_EDITABLE;
 }
 
+void rna_Object_lightgroup_get(PointerRNA *ptr, char *value)
+{
+  BKE_lightgroup_membership_get(((Object *)ptr->owner_id)->lightgroup, value);
+}
+
+int rna_Object_lightgroup_length(PointerRNA *ptr)
+{
+  return BKE_lightgroup_membership_length(((Object *)ptr->owner_id)->lightgroup);
+}
+
+void rna_Object_lightgroup_set(PointerRNA *ptr, const char *value)
+{
+  BKE_lightgroup_membership_set(&((Object *)ptr->owner_id)->lightgroup, value);
+}
+
 #else
 
 static void rna_def_vertex_group(BlenderRNA *brna)
@@ -3775,6 +3790,15 @@ static void rna_def_object(BlenderRNA *brna)
   RNA_def_property_editable_func(prop, "rna_Object_mesh_symmetry_yz_editable");
   RNA_def_property_ui_text(prop, "Z", "Enable mesh symmetry in the Z axis");
 
+  /* Lightgroup Membership */
+  prop = RNA_def_property(srna, "lightgroup", PROP_STRING, PROP_NONE);
+  RNA_def_property_string_funcs(prop,
+                                "rna_Object_lightgroup_get",
+                                "rna_Object_lightgroup_length",
+                                "rna_Object_lightgroup_set");
+  RNA_def_property_flag(prop, PROP_EDITABLE);
+  RNA_def_property_ui_text(prop, "Lightgroup", "Lightgroup that the object belongs to");
+
   RNA_define_lib_overridable(false);
 
   /* anim */

source/blender/makesrna/intern/rna_scene.c

@@ -1767,6 +1767,10 @@ void rna_ViewLayer_pass_update(Main *bmain, Scene *activescene, PointerRNA *ptr)
     ViewLayerAOV *aov = (ViewLayerAOV *)ptr->data;
     view_layer = BKE_view_layer_find_with_aov(scene, aov);
   }
+  else if (ptr->type == &RNA_Lightgroup) {
+    ViewLayerLightgroup *lightgroup = (ViewLayerLightgroup *)ptr->data;
+    view_layer = BKE_view_layer_find_with_lightgroup(scene, lightgroup);
+  }
 
   if (view_layer) {
     RenderEngineType *engine_type = RE_engines_find(scene->r.engine);
@@ -2447,6 +2451,49 @@ void rna_ViewLayer_active_aov_index_set(PointerRNA *ptr, int value)
   view_layer->active_aov = aov;
 }
 
+void rna_ViewLayer_active_lightgroup_index_range(
+    PointerRNA *ptr, int *min, int *max, int *UNUSED(softmin), int *UNUSED(softmax))
+{
+  ViewLayer *view_layer = (ViewLayer *)ptr->data;
+
+  *min = 0;
+  *max = max_ii(0, BLI_listbase_count(&view_layer->lightgroups) - 1);
+}
+
+int rna_ViewLayer_active_lightgroup_index_get(PointerRNA *ptr)
+{
+  ViewLayer *view_layer = (ViewLayer *)ptr->data;
+  return BLI_findindex(&view_layer->lightgroups, view_layer->active_lightgroup);
+}
+
+void rna_ViewLayer_active_lightgroup_index_set(PointerRNA *ptr, int value)
+{
+  ViewLayer *view_layer = (ViewLayer *)ptr->data;
+  ViewLayerLightgroup *lightgroup = BLI_findlink(&view_layer->lightgroups, value);
+  view_layer->active_lightgroup = lightgroup;
+}
+
+static void rna_ViewLayerLightgroup_name_get(PointerRNA *ptr, char *value)
+{
+  ViewLayerLightgroup *lightgroup = (ViewLayerLightgroup *)ptr->data;
+  BLI_strncpy(value, lightgroup->name, sizeof(lightgroup->name));
+}
+
+static int rna_ViewLayerLightgroup_name_length(PointerRNA *ptr)
+{
+  ViewLayerLightgroup *lightgroup = (ViewLayerLightgroup *)ptr->data;
+  return strlen(lightgroup->name);
+}
+
+static void rna_ViewLayerLightgroup_name_set(PointerRNA *ptr, const char *value)
+{
+  ViewLayerLightgroup *lightgroup = (ViewLayerLightgroup *)ptr->data;
+  Scene *scene = (Scene *)ptr->owner_id;
+  ViewLayer *view_layer = BKE_view_layer_find_with_lightgroup(scene, lightgroup);
+
+  BKE_view_layer_rename_lightgroup(view_layer, lightgroup, value);
+}
+
 /* Fake value, used internally (not saved to DNA). */
 #  define V3D_ORIENT_DEFAULT -1
 
@@ -4156,6 +4203,43 @@ static void rna_def_view_layer_aov(BlenderRNA *brna)
   RNA_def_property_update(prop, NC_SCENE | ND_RENDER_OPTIONS, "rna_ViewLayer_pass_update");
 }
 
+static void rna_def_view_layer_lightgroups(BlenderRNA *brna, PropertyRNA *cprop)
+{
+  StructRNA *srna;
+  /*  PropertyRNA *prop; */
+
+  FunctionRNA *func;
+  PropertyRNA *parm;
+
+  RNA_def_property_srna(cprop, "Lightgroups");
+  srna = RNA_def_struct(brna, "Lightgroups", NULL);
+  RNA_def_struct_sdna(srna, "ViewLayer");
+  RNA_def_struct_ui_text(srna, "List of Lightgroups", "Collection of Lightgroups");
+
+  func = RNA_def_function(srna, "add", "BKE_view_layer_add_lightgroup");
+  parm = RNA_def_pointer(func, "lightgroup", "Lightgroup", "", "Newly created Lightgroup");
+  RNA_def_function_return(func, parm);
+}
+
+static void rna_def_view_layer_lightgroup(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+  srna = RNA_def_struct(brna, "Lightgroup", NULL);
+  RNA_def_struct_sdna(srna, "ViewLayerLightgroup");
+  RNA_def_struct_ui_text(srna, "Light Group", "");
+
+  prop = RNA_def_property(srna, "name", PROP_STRING, PROP_NONE);
+  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+  RNA_def_property_string_funcs(prop,
+                                "rna_ViewLayerLightgroup_name_get",
+                                "rna_ViewLayerLightgroup_name_length",
+                                "rna_ViewLayerLightgroup_name_set");
+  RNA_def_property_ui_text(prop, "Name", "Name of the Lightgroup");
+  RNA_def_property_update(prop, NC_SCENE | ND_RENDER_OPTIONS, "rna_ViewLayer_pass_update");
+  RNA_def_struct_name_property(srna, prop);
+}
+
 void rna_def_view_layer_common(BlenderRNA *brna, StructRNA *srna, const bool scene)
 {
   PropertyRNA *prop;
@@ -4226,6 +4310,25 @@ void rna_def_view_layer_common(BlenderRNA *brna, StructRNA *srna, const bool sce
     RNA_def_property_ui_text(prop, "Active AOV Index", "Index of active aov");
     RNA_def_property_update(prop, NC_SCENE | ND_RENDER_OPTIONS, NULL);
 
+    prop = RNA_def_property(srna, "lightgroups", PROP_COLLECTION, PROP_NONE);
+    RNA_def_property_collection_sdna(prop, NULL, "lightgroups", NULL);
+    RNA_def_property_struct_type(prop, "Lightgroup");
+    RNA_def_property_ui_text(prop, "Light Groups", "");
+    rna_def_view_layer_lightgroups(brna, prop);
+
+    prop = RNA_def_property(srna, "active_lightgroup", PROP_POINTER, PROP_NONE);
+    RNA_def_property_struct_type(prop, "Lightgroup");
+    RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+    RNA_def_property_ui_text(prop, "Light Groups", "Active Lightgroup");
+
+    prop = RNA_def_property(srna, "active_lightgroup_index", PROP_INT, PROP_UNSIGNED);
+    RNA_def_property_int_funcs(prop,
+                               "rna_ViewLayer_active_lightgroup_index_get",
+                               "rna_ViewLayer_active_lightgroup_index_set",
+                               "rna_ViewLayer_active_lightgroup_index_range");
+    RNA_def_property_ui_text(prop, "Active Lightgroup Index", "Index of active lightgroup");
+    RNA_def_property_update(prop, NC_SCENE | ND_RENDER_OPTIONS, NULL);
+
     prop = RNA_def_property(srna, "use_pass_cryptomatte_object", PROP_BOOLEAN, PROP_NONE);
     RNA_def_property_boolean_sdna(prop, NULL, "cryptomatte_flag", VIEW_LAYER_CRYPTOMATTE_OBJECT);
     RNA_def_property_ui_text(
@@ -8088,6 +8191,7 @@ void RNA_def_scene(BlenderRNA *brna)
   rna_def_scene_display(brna);
   rna_def_scene_eevee(brna);
   rna_def_view_layer_aov(brna);
+  rna_def_view_layer_lightgroup(brna);
   rna_def_view_layer_eevee(brna);
   rna_def_scene_gpencil(brna);
   RNA_define_animate_sdna(true);

source/blender/makesrna/intern/rna_world.c

@@ -22,6 +22,7 @@
 #  include "MEM_guardedalloc.h"
 
 #  include "BKE_context.h"
+#  include "BKE_layer.h"
 #  include "BKE_main.h"
 #  include "BKE_texture.h"
 
@@ -84,6 +85,21 @@ static void rna_World_use_nodes_update(bContext *C, PointerRNA *ptr)
   rna_World_draw_update(bmain, scene, ptr);
 }
 
+void rna_World_lightgroup_get(PointerRNA *ptr, char *value)
+{
+  BKE_lightgroup_membership_get(((World *)ptr->owner_id)->lightgroup, value);
+}
+
+int rna_World_lightgroup_length(PointerRNA *ptr)
+{
+  return BKE_lightgroup_membership_length(((World *)ptr->owner_id)->lightgroup);
+}
+
+void rna_World_lightgroup_set(PointerRNA *ptr, const char *value)
+{
+  BKE_lightgroup_membership_set(&((World *)ptr->owner_id)->lightgroup, value);
+}
+
 #else
 
 static void rna_def_lighting(BlenderRNA *brna)
@@ -234,6 +250,13 @@ void RNA_def_world(BlenderRNA *brna)
   RNA_def_property_ui_text(prop, "Use Nodes", "Use shader nodes to render the world");
   RNA_def_property_update(prop, 0, "rna_World_use_nodes_update");
 
+  /* Lightgroup Membership */
+  prop = RNA_def_property(srna, "lightgroup", PROP_STRING, PROP_NONE);
+  RNA_def_property_string_funcs(
+      prop, "rna_World_lightgroup_get", "rna_World_lightgroup_length", "rna_World_lightgroup_set");
+  RNA_def_property_flag(prop, PROP_EDITABLE);
+  RNA_def_property_ui_text(prop, "Lightgroup", "Lightgroup that the world belongs to");
+
   rna_def_lighting(brna);
   rna_def_world_mist(brna);
 }