Geometry: add .attributes in the Python API for Mesh, Hair and Point Cloud

This puts all generic float/int/vector/color/string geometry attributes in a new
.attributes property. For meshes it provides a more general API for existing
attributes, for point clouds attributes will be used as an essential part of
particle nodes.

This patch was implemented by @lichtwerk, with further changes by me. It's
still a work in progress, but posting here to show what is going on and for
early feedback.

Ref T76659

Differential Revision: https://developer.blender.org/D8200

1 files changed, 662 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_attribute.c b/source/blender/makesrna/intern/rna_attribute.c
new file mode 100644
index 00000000000..a0bb5f67a08
--- /dev/null
+++ b/source/blender/makesrna/intern/rna_attribute.c
@@ -0,0 +1,662 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file
+ * \ingroup RNA
+ */
+
+#include <stdlib.h>
+
+#include "RNA_access.h"
+#include "RNA_define.h"
+#include "RNA_enum_types.h"
+
+#include "rna_internal.h"
+
+#include "DNA_customdata_types.h"
+#include "DNA_hair_types.h"
+#include "DNA_mesh_types.h"
+#include "DNA_meshdata_types.h"
+#include "DNA_pointcloud_types.h"
+
+#include "BKE_attribute.h"
+#include "BKE_customdata.h"
+
+#include "WM_types.h"
+
+static const EnumPropertyItem rna_enum_attribute_type_items[] = {
+    {CD_PROP_FLOAT, "FLOAT", 0, "Float", "Floating point value"},
+    {CD_PROP_INT32, "INT", 0, "Integer", "32 bit integer"},
+    {CD_PROP_FLOAT3, "FLOAT_VECTOR", 0, "Vector", "3D vector with floating point values"},
+    {CD_PROP_COLOR, "FLOAT_COLOR", 0, "Float Color", "RGBA color with floating point precisions"},
+    {CD_MLOOPCOL, "BYTE_COLOR", 0, "Byte Color", "RGBA color with 8-bit precision"},
+    {CD_PROP_STRING, "STRING", 0, "String", "Text string"},
+    {0, NULL, 0, NULL, NULL},
+};
+
+static const EnumPropertyItem rna_enum_attribute_domain_items[] = {
+    /* Not implement yet
+    {ATTR_DOMAIN_GEOMETRY, "GEOMETRY", 0, "Geometry", "Attribute on (whole) geometry"}, */
+    {ATTR_DOMAIN_VERTEX, "VERTEX", 0, "Vertex", "Attribute on mesh vertex"},
+    {ATTR_DOMAIN_EDGE, "EDGE", 0, "Edge", "Attribute on mesh edge"},
+    {ATTR_DOMAIN_CORNER, "CORNER", 0, "Corner", "Attribute on mesh polygon corner"},
+    {ATTR_DOMAIN_POLYGON, "POLYGON", 0, "Polygon", "Attribute on mesh polygons"},
+    /* Not implement yet
+    {ATTR_DOMAIN_GRIDS, "GRIDS", 0, "Grids", "Attribute on mesh multires grids"}, */
+    {ATTR_DOMAIN_POINT, "POINT", 0, "Point", "Attribute on point"},
+    {ATTR_DOMAIN_CURVE, "CURVE", 0, "Curve", "Attribute on hair curve"},
+    {0, NULL, 0, NULL, NULL},
+};
+
+#ifdef RNA_RUNTIME
+
+#  include "BLI_math.h"
+
+#  include "DEG_depsgraph.h"
+
+#  include "WM_api.h"
+
+/* Attribute */
+
+static char *rna_Attribute_path(PointerRNA *ptr)
+{
+  CustomDataLayer *layer = ptr->data;
+  return BLI_sprintfN("attributes['%s']", layer->name);
+}
+
+static void rna_Attribute_name_set(PointerRNA *ptr, const char *value)
+{
+  BKE_id_attribute_rename(ptr->owner_id, ptr->data, value, NULL);
+}
+
+static int rna_Attribute_type_get(PointerRNA *ptr)
+{
+  CustomDataLayer *layer = ptr->data;
+  return layer->type;
+}
+
+static const EnumPropertyItem *rna_Attribute_domain_itemf(bContext *UNUSED(C),
+                                                          PointerRNA *ptr,
+                                                          PropertyRNA *UNUSED(prop),
+                                                          bool *r_free)
+{
+  EnumPropertyItem *item = NULL;
+  const EnumPropertyItem *domain_item = NULL;
+  ID *id = ptr->owner_id;
+  const ID_Type id_type = GS(id->name);
+  int totitem = 0, a;
+
+  for (a = 0; rna_enum_attribute_domain_items[a].identifier; a++) {
+    domain_item = &rna_enum_attribute_domain_items[a];
+
+    if (id_type == ID_PT && !ELEM(domain_item->value, ATTR_DOMAIN_POINT)) {
+      continue;
+    }
+    if (id_type == ID_HA && !ELEM(domain_item->value, ATTR_DOMAIN_POINT, ATTR_DOMAIN_CURVE)) {
+      continue;
+    }
+    if (id_type == ID_ME && ELEM(domain_item->value, ATTR_DOMAIN_POINT, ATTR_DOMAIN_CURVE)) {
+      continue;
+    }
+
+    RNA_enum_item_add(&item, &totitem, domain_item);
+  }
+  RNA_enum_item_end(&item, &totitem);
+
+  *r_free = true;
+  return item;
+}
+
+static int rna_Attribute_domain_get(PointerRNA *ptr)
+{
+  return BKE_id_attribute_domain(ptr->owner_id, ptr->data);
+}
+
+static void rna_Attribute_data_begin(CollectionPropertyIterator *iter, PointerRNA *ptr)
+{
+  ID *id = ptr->owner_id;
+  CustomDataLayer *layer = (CustomDataLayer *)ptr->data;
+
+  int length = BKE_id_attribute_data_length(id, layer);
+  size_t struct_size;
+
+  switch (layer->type) {
+    case CD_PROP_FLOAT:
+      struct_size = sizeof(MFloatProperty);
+      break;
+    case CD_PROP_INT32:
+      struct_size = sizeof(MIntProperty);
+      break;
+    case CD_PROP_FLOAT3:
+      struct_size = sizeof(float[3]);
+      break;
+    case CD_PROP_COLOR:
+      struct_size = sizeof(MPropCol);
+      break;
+    case CD_MLOOPCOL:
+      struct_size = sizeof(MLoopCol);
+      break;
+    case CD_PROP_STRING:
+      struct_size = sizeof(MStringProperty);
+      break;
+    default:
+      struct_size = 0;
+      length = 0;
+      break;
+  }
+
+  rna_iterator_array_begin(iter, layer->data, struct_size, length, 0, NULL);
+}
+
+static int rna_Attribute_data_length(PointerRNA *ptr)
+{
+  ID *id = ptr->owner_id;
+  CustomDataLayer *layer = (CustomDataLayer *)ptr->data;
+  return BKE_id_attribute_data_length(id, layer);
+}
+
+static void rna_Attribute_update_data(Main *UNUSED(bmain), Scene *UNUSED(scene), PointerRNA *ptr)
+{
+  ID *id = ptr->owner_id;
+
+  /* cheating way for importers to avoid slow updates */
+  if (id->us > 0) {
+    DEG_id_tag_update(id, 0);
+    WM_main_add_notifier(NC_GEOM | ND_DATA, id);
+  }
+}
+
+/* Color Attribute */
+
+static void rna_ByteColorAttributeValue_color_get(PointerRNA *ptr, float *values)
+{
+  MLoopCol *mlcol = (MLoopCol *)ptr->data;
+  srgb_to_linearrgb_uchar4(values, &mlcol->r);
+}
+
+static void rna_ByteColorAttributeValue_color_set(PointerRNA *ptr, const float *values)
+{
+  MLoopCol *mlcol = (MLoopCol *)ptr->data;
+  linearrgb_to_srgb_uchar4(&mlcol->r, values);
+}
+
+/* Attribute Group */
+
+static PointerRNA rna_AttributeGroup_new(
+    ID *id, ReportList *reports, const char *name, const int type, const int domain)
+{
+  CustomDataLayer *layer = BKE_id_attribute_new(id, name, type, domain, reports);
+  DEG_id_tag_update(id, ID_RECALC_GEOMETRY);
+  WM_main_add_notifier(NC_GEOM | ND_DATA, id);
+
+  PointerRNA ptr;
+  RNA_pointer_create(id, &RNA_Attribute, layer, &ptr);
+  return ptr;
+}
+
+static void rna_AttributeGroup_remove(ID *id, ReportList *reports, PointerRNA *attribute_ptr)
+{
+  CustomDataLayer *layer = (CustomDataLayer *)attribute_ptr->data;
+  BKE_id_attribute_remove(id, layer, reports);
+  RNA_POINTER_INVALIDATE(attribute_ptr);
+
+  DEG_id_tag_update(id, ID_RECALC_GEOMETRY);
+  WM_main_add_notifier(NC_GEOM | ND_DATA, id);
+}
+
+static int rna_Attributes_layer_skip(CollectionPropertyIterator *UNUSED(iter), void *data)
+{
+  CustomDataLayer *layer = (CustomDataLayer *)data;
+  return !(CD_TYPE_AS_MASK(layer->type) & CD_MASK_PROP_ALL);
+}
+
+/* Attributes are spread over multiple domains in separate CustomData, we use repeated
+ * array iterators to loop over all. */
+static void rna_AttributeGroup_next_domain(ID *id,
+                                           CollectionPropertyIterator *iter,
+                                           int(skip)(CollectionPropertyIterator *iter, void *data))
+{
+  do {
+    CustomDataLayer *prev_layers = (CustomDataLayer *)iter->internal.array.endptr -
+                                   iter->internal.array.length;
+    CustomData *customdata = BKE_id_attributes_iterator_next_domain(id, prev_layers);
+    if (customdata == NULL) {
+      return;
+    }
+    rna_iterator_array_begin(
+        iter, customdata->layers, sizeof(CustomDataLayer), customdata->totlayer, false, skip);
+  } while (!iter->valid);
+}
+
+void rna_AttributeGroup_iterator_begin(CollectionPropertyIterator *iter, PointerRNA *ptr)
+{
+  memset(&iter->internal.array, 0, sizeof(iter->internal.array));
+  rna_AttributeGroup_next_domain(ptr->owner_id, iter, rna_Attributes_layer_skip);
+}
+
+void rna_AttributeGroup_iterator_next(CollectionPropertyIterator *iter)
+{
+  rna_iterator_array_next(iter);
+
+  if (!iter->valid) {
+    ID *id = iter->parent.owner_id;
+    rna_AttributeGroup_next_domain(id, iter, rna_Attributes_layer_skip);
+  }
+}
+
+PointerRNA rna_AttributeGroup_iterator_get(CollectionPropertyIterator *iter)
+{
+  /* refine to the proper type */
+  StructRNA *type;
+  CustomDataLayer *layer = rna_iterator_array_get(iter);
+
+  switch (layer->type) {
+    case CD_PROP_FLOAT:
+      type = &RNA_FloatAttribute;
+      break;
+    case CD_PROP_INT32:
+      type = &RNA_IntAttribute;
+      break;
+    case CD_PROP_FLOAT3:
+      type = &RNA_FloatVectorAttribute;
+      break;
+    case CD_PROP_COLOR:
+      type = &RNA_FloatColorAttribute;
+      break;
+    case CD_MLOOPCOL:
+      type = &RNA_ByteColorAttribute;
+      break;
+    case CD_PROP_STRING:
+      type = &RNA_StringAttribute;
+      break;
+    default:
+      return PointerRNA_NULL;
+  }
+
+  return rna_pointer_inherit_refine(&iter->parent, type, layer);
+}
+
+int rna_AttributeGroup_length(PointerRNA *ptr)
+{
+  return BKE_id_attributes_length(ptr->owner_id, CD_MASK_PROP_ALL);
+}
+
+static int rna_AttributeGroup_active_index_get(PointerRNA *ptr)
+{
+  return *BKE_id_attributes_active_index_p(ptr->owner_id);
+}
+
+static PointerRNA rna_AttributeGroup_active_get(PointerRNA *ptr)
+{
+  ID *id = ptr->owner_id;
+  CustomDataLayer *layer = BKE_id_attributes_active_get(id);
+
+  PointerRNA attribute_ptr;
+  RNA_pointer_create(id, &RNA_Attribute, layer, &attribute_ptr);
+  return attribute_ptr;
+}
+
+static void rna_AttributeGroup_active_set(PointerRNA *ptr,
+                                          PointerRNA attribute_ptr,
+                                          ReportList *UNUSED(reports))
+{
+  ID *id = ptr->owner_id;
+  CustomDataLayer *layer = attribute_ptr.data;
+  BKE_id_attributes_active_set(id, layer);
+}
+
+static void rna_AttributeGroup_active_index_set(PointerRNA *ptr, int value)
+{
+  *BKE_id_attributes_active_index_p(ptr->owner_id) = value;
+}
+
+static void rna_AttributeGroup_active_index_range(
+    PointerRNA *ptr, int *min, int *max, int *softmin, int *softmax)
+{
+  *min = 0;
+  *max = BKE_id_attributes_length(ptr->owner_id, CD_MASK_PROP_ALL);
+
+  *softmin = *min;
+  *softmax = *max;
+}
+
+static void rna_AttributeGroup_update_active(Main *bmain, Scene *scene, PointerRNA *ptr)
+{
+  rna_Attribute_update_data(bmain, scene, ptr);
+}
+
+#else
+
+static void rna_def_attribute_float(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+
+  srna = RNA_def_struct(brna, "FloatAttribute", "Attribute");
+  RNA_def_struct_sdna(srna, "CustomDataLayer");
+  RNA_def_struct_ui_text(srna, "Float Attribute", "Geometry attribute with floating point values");
+
+  prop = RNA_def_property(srna, "data", PROP_COLLECTION, PROP_NONE);
+  RNA_def_property_struct_type(prop, "FloatAttributeValue");
+  RNA_def_property_collection_funcs(prop,
+                                    "rna_Attribute_data_begin",
+                                    "rna_iterator_array_next",
+                                    "rna_iterator_array_end",
+                                    "rna_iterator_array_get",
+                                    "rna_Attribute_data_length",
+                                    NULL,
+                                    NULL,
+                                    NULL);
+
+  srna = RNA_def_struct(brna, "FloatAttributeValue", NULL);
+  RNA_def_struct_sdna(srna, "MFloatProperty");
+  RNA_def_struct_ui_text(
+      srna, "Float Attribute Value", "Floating point value in geometry attribute");
+  prop = RNA_def_property(srna, "value", PROP_FLOAT, PROP_NONE);
+  RNA_def_property_float_sdna(prop, NULL, "f");
+  RNA_def_property_update(prop, 0, "rna_Attribute_update_data");
+}
+
+static void rna_def_attribute_float_vector(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+
+  /* Float Vector Attribute */
+  srna = RNA_def_struct(brna, "FloatVectorAttribute", "Attribute");
+  RNA_def_struct_sdna(srna, "CustomDataLayer");
+  RNA_def_struct_ui_text(
+      srna, "Float Vector Attribute", "Vector geometry attribute, with floating point precision");
+
+  prop = RNA_def_property(srna, "data", PROP_COLLECTION, PROP_NONE);
+  RNA_def_property_struct_type(prop, "FloatVectorAttributeValue");
+  RNA_def_property_collection_funcs(prop,
+                                    "rna_Attribute_data_begin",
+                                    "rna_iterator_array_next",
+                                    "rna_iterator_array_end",
+                                    "rna_iterator_array_get",
+                                    "rna_Attribute_data_length",
+                                    NULL,
+                                    NULL,
+                                    NULL);
+
+  /* Float Vector Attribute Value */
+  srna = RNA_def_struct(brna, "FloatVectorAttributeValue", NULL);
+  RNA_def_struct_sdna(srna, "vec3f");
+  RNA_def_struct_ui_text(
+      srna, "Float Vector Attribute Value", "Vector value in geometry attribute");
+
+  prop = RNA_def_property(srna, "vector", PROP_FLOAT, PROP_DIRECTION);
+  RNA_def_property_ui_text(prop, "Vector", "3D vector");
+  RNA_def_property_float_sdna(prop, NULL, "x");
+  RNA_def_property_array(prop, 3);
+  RNA_def_property_update(prop, 0, "rna_Attribute_update_data");
+}
+
+static void rna_def_attribute_float_color(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+
+  /* Float Color Attribute */
+  srna = RNA_def_struct(brna, "FloatColorAttribute", "Attribute");
+  RNA_def_struct_sdna(srna, "CustomDataLayer");
+  RNA_def_struct_ui_text(
+      srna, "Float Color Attribute", "Color geometry attribute, with floating point precision");
+
+  prop = RNA_def_property(srna, "data", PROP_COLLECTION, PROP_NONE);
+  RNA_def_property_struct_type(prop, "FloatColorAttributeValue");
+  RNA_def_property_collection_funcs(prop,
+                                    "rna_Attribute_data_begin",
+                                    "rna_iterator_array_next",
+                                    "rna_iterator_array_end",
+                                    "rna_iterator_array_get",
+                                    "rna_Attribute_data_length",
+                                    NULL,
+                                    NULL,
+                                    NULL);
+
+  /* Float Color Attribute Value */
+  srna = RNA_def_struct(brna, "FloatColorAttributeValue", NULL);
+  RNA_def_struct_sdna(srna, "MPropCol");
+  RNA_def_struct_ui_text(srna, "Float Color Attribute Value", "Color value in geometry attribute");
+
+  prop = RNA_def_property(srna, "color", PROP_FLOAT, PROP_COLOR);
+  RNA_def_property_ui_text(prop, "Color", "RGBA color in scene linear color space");
+  RNA_def_property_float_sdna(prop, NULL, "color");
+  RNA_def_property_array(prop, 4);
+  RNA_def_property_update(prop, 0, "rna_Attribute_update_data");
+}
+
+static void rna_def_attribute_byte_color(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+
+  /* Byte Color Attribute */
+  srna = RNA_def_struct(brna, "ByteColorAttribute", "Attribute");
+  RNA_def_struct_sdna(srna, "CustomDataLayer");
+  RNA_def_struct_ui_text(
+      srna, "Byte Color Attribute", "Color geometry attribute, with 8-bit precision");
+
+  prop = RNA_def_property(srna, "data", PROP_COLLECTION, PROP_NONE);
+  RNA_def_property_struct_type(prop, "ByteColorAttributeValue");
+  RNA_def_property_collection_funcs(prop,
+                                    "rna_Attribute_data_begin",
+                                    "rna_iterator_array_next",
+                                    "rna_iterator_array_end",
+                                    "rna_iterator_array_get",
+                                    "rna_Attribute_data_length",
+                                    NULL,
+                                    NULL,
+                                    NULL);
+
+  /* Byte Color Attribute Value */
+  srna = RNA_def_struct(brna, "ByteColorAttributeValue", NULL);
+  RNA_def_struct_sdna(srna, "MLoopCol");
+  RNA_def_struct_ui_text(srna, "Byte Color Attribute Value", "Color value in geometry attribute");
+
+  prop = RNA_def_property(srna, "color", PROP_FLOAT, PROP_COLOR);
+  RNA_def_property_array(prop, 4);
+  RNA_def_property_range(prop, 0.0f, 1.0f);
+  RNA_def_property_float_funcs(prop,
+                               "rna_ByteColorAttributeValue_color_get",
+                               "rna_ByteColorAttributeValue_color_set",
+                               NULL);
+  RNA_def_property_ui_text(prop, "Color", "RGBA color in scene linear color space");
+  RNA_def_property_update(prop, 0, "rna_Attribute_update_data");
+}
+
+static void rna_def_attribute_int(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+
+  srna = RNA_def_struct(brna, "IntAttribute", "Attribute");
+  RNA_def_struct_sdna(srna, "CustomDataLayer");
+  RNA_def_struct_ui_text(srna, "Int Attribute", "Integer geometry attribute");
+
+  prop = RNA_def_property(srna, "data", PROP_COLLECTION, PROP_NONE);
+  RNA_def_property_struct_type(prop, "IntAttributeValue");
+  RNA_def_property_collection_funcs(prop,
+                                    "rna_Attribute_data_begin",
+                                    "rna_iterator_array_next",
+                                    "rna_iterator_array_end",
+                                    "rna_iterator_array_get",
+                                    "rna_Attribute_data_length",
+                                    NULL,
+                                    NULL,
+                                    NULL);
+
+  srna = RNA_def_struct(brna, "IntAttributeValue", NULL);
+  RNA_def_struct_sdna(srna, "MIntProperty");
+  RNA_def_struct_ui_text(srna, "Integer Attribute Value", "Integer value in geometry attribute");
+  prop = RNA_def_property(srna, "value", PROP_INT, PROP_NONE);
+  RNA_def_property_int_sdna(prop, NULL, "i");
+  RNA_def_property_update(prop, 0, "rna_Attribute_update_data");
+}
+
+static void rna_def_attribute_string(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+
+  srna = RNA_def_struct(brna, "StringAttribute", "Attribute");
+  RNA_def_struct_sdna(srna, "CustomDataLayer");
+  RNA_def_struct_ui_text(srna, "String Attribute", "String geometry attribute");
+
+  prop = RNA_def_property(srna, "data", PROP_COLLECTION, PROP_NONE);
+  RNA_def_property_struct_type(prop, "StringAttributeValue");
+  RNA_def_property_collection_funcs(prop,
+                                    "rna_Attribute_data_begin",
+                                    "rna_iterator_array_next",
+                                    "rna_iterator_array_end",
+                                    "rna_iterator_array_get",
+                                    "rna_Attribute_data_length",
+                                    NULL,
+                                    NULL,
+                                    NULL);
+
+  srna = RNA_def_struct(brna, "StringAttributeValue", NULL);
+  RNA_def_struct_sdna(srna, "MStringProperty");
+  RNA_def_struct_ui_text(srna, "String Attribute Value", "String value in geometry attribute");
+  prop = RNA_def_property(srna, "value", PROP_STRING, PROP_NONE);
+  RNA_def_property_string_sdna(prop, NULL, "s");
+  RNA_def_property_update(prop, 0, "rna_Attribute_update_data");
+}
+
+static void rna_def_attribute(BlenderRNA *brna)
+{
+  PropertyRNA *prop;
+  StructRNA *srna;
+
+  srna = RNA_def_struct(brna, "Attribute", NULL);
+  RNA_def_struct_sdna(srna, "CustomDataLayer");
+  RNA_def_struct_ui_text(srna, "Attribute", "Geometry attribute");
+  RNA_def_struct_path_func(srna, "rna_Attribute_path");
+
+  prop = RNA_def_property(srna, "name", PROP_STRING, PROP_NONE);
+  RNA_def_struct_name_property(srna, prop);
+  RNA_def_property_string_funcs(prop, NULL, NULL, "rna_Attribute_name_set");
+  RNA_def_property_ui_text(prop, "Name", "Name of the Attribute");
+  RNA_def_struct_name_property(srna, prop);
+
+  prop = RNA_def_property(srna, "data_type", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_sdna(prop, NULL, "type");
+  RNA_def_property_enum_items(prop, rna_enum_attribute_type_items);
+  RNA_def_property_enum_funcs(prop, "rna_Attribute_type_get", NULL, NULL);
+  RNA_def_property_ui_text(prop, "Data Type", "Type of data stored in attribute");
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+
+  prop = RNA_def_property(srna, "domain", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_items(prop, rna_enum_attribute_domain_items);
+  RNA_def_property_enum_funcs(
+      prop, "rna_Attribute_domain_get", NULL, "rna_Attribute_domain_itemf");
+  RNA_def_property_ui_text(prop, "Domain", "Domain of the Attribute");
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+
+  /* types */
+  rna_def_attribute_float(brna);
+  rna_def_attribute_float_vector(brna);
+  rna_def_attribute_float_color(brna);
+  rna_def_attribute_byte_color(brna);
+  rna_def_attribute_int(brna);
+  rna_def_attribute_string(brna);
+}
+
+/* Mesh/PointCloud/Hair.attributes */
+static void rna_def_attribute_group(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+  FunctionRNA *func;
+  PropertyRNA *parm;
+
+  srna = RNA_def_struct(brna, "AttributeGroup", NULL);
+  RNA_def_struct_ui_text(srna, "Attribute Group", "Group of geometry attributes");
+  RNA_def_struct_sdna(srna, "ID");
+
+  /* API */
+  func = RNA_def_function(srna, "new", "rna_AttributeGroup_new");
+  RNA_def_function_ui_description(func, "Add an attribute");
+  RNA_def_function_flag(func, FUNC_USE_REPORTS);
+  parm = RNA_def_string(func, "name", "Attribute", 0, "", "Attribute name");
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+  parm = RNA_def_enum(
+      func, "type", rna_enum_attribute_type_items, CD_PROP_FLOAT, "Type", "Attribute type");
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+  parm = RNA_def_enum(func,
+                      "domain",
+                      rna_enum_attribute_domain_items,
+                      ATTR_DOMAIN_VERTEX,
+                      "Domain",
+                      "Attribute domain");
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+  parm = RNA_def_pointer(func, "attribute", "Attribute", "", "New geometry attribute");
+  RNA_def_parameter_flags(parm, 0, PARM_RNAPTR);
+  RNA_def_function_return(func, parm);
+
+  func = RNA_def_function(srna, "remove", "rna_AttributeGroup_remove");
+  RNA_def_function_ui_description(func, "Remove an attribute");
+  RNA_def_function_flag(func, FUNC_USE_REPORTS);
+  parm = RNA_def_pointer(func, "attribute", "Attribute", "", "Geometry Attribute");
+  RNA_def_parameter_flags(parm, PROP_NEVER_NULL, PARM_REQUIRED | PARM_RNAPTR);
+  RNA_def_parameter_clear_flags(parm, PROP_THICK_WRAP, 0);
+
+  /* Active */
+  prop = RNA_def_property(srna, "active", PROP_POINTER, PROP_NONE);
+  RNA_def_property_struct_type(prop, "Attribute");
+  RNA_def_property_pointer_funcs(
+      prop, "rna_AttributeGroup_active_get", "rna_AttributeGroup_active_set", NULL, NULL);
+  RNA_def_property_flag(prop, PROP_EDITABLE | PROP_NEVER_UNLINK);
+  RNA_def_property_ui_text(prop, "Active Attribute", "Active attribute");
+  RNA_def_property_update(prop, 0, "rna_AttributeGroup_update_active");
+
+  prop = RNA_def_property(srna, "active_index", PROP_INT, PROP_NONE);
+  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+  RNA_def_property_int_funcs(prop,
+                             "rna_AttributeGroup_active_index_get",
+                             "rna_AttributeGroup_active_index_set",
+                             "rna_AttributeGroup_active_index_range");
+  RNA_def_property_update(prop, 0, "rna_AttributeGroup_update_active");
+}
+
+void rna_def_attributes_common(StructRNA *srna)
+{
+  PropertyRNA *prop;
+
+  /* Attributes */
+  prop = RNA_def_property(srna, "attributes", PROP_COLLECTION, PROP_NONE);
+  RNA_def_property_collection_funcs(prop,
+                                    "rna_AttributeGroup_iterator_begin",
+                                    "rna_AttributeGroup_iterator_next",
+                                    "rna_iterator_array_end",
+                                    "rna_AttributeGroup_iterator_get",
+                                    "rna_AttributeGroup_length",
+                                    NULL,
+                                    NULL,
+                                    NULL);
+  RNA_def_property_struct_type(prop, "Attribute");
+  RNA_def_property_ui_text(prop, "Attributes", "Geometry attributes");
+  RNA_def_property_srna(prop, "AttributeGroup");
+}
+
+void RNA_def_attribute(BlenderRNA *brna)
+{
+  rna_def_attribute(brna);
+  rna_def_attribute_group(brna);
+}
+#endif