Geometry Nodes: Add Attribute Convert node

The Attribute Convert node provides functionality to change attributes
between different domains and data types. Before it was impossible to
write to a UV Map attribute with the attribute math nodes since they
did not output a 2D vector type. This makes it possible to
"convert into" a UV map attribute.

The data type conversion uses the implicit conversions provided by
`\nodes\intern\node_tree_multi_function.cc`.

The `Auto` domain mode chooses the domain based on the following rules:
1. If the result attribute already exists, use that domain.
2. If the result attribute doesn't exist, use the source attribute domain.
3. Otherwise use the default domain (points).

See {T85700}

Differential Revision: https://developer.blender.org/D10624

10 files changed, 225 insertions, 0 deletions

diff --git a/release/scripts/startup/nodeitems_builtins.py b/release/scripts/startup/nodeitems_builtins.py
index f9a789f800b..c6565f1b578 100644
--- a/release/scripts/startup/nodeitems_builtins.py
+++ b/release/scripts/startup/nodeitems_builtins.py
@@ -485,6 +485,7 @@ geometry_node_categories = [
         NodeItem("GeometryNodeAttributeRandomize"),
         NodeItem("GeometryNodeAttributeMath"),
         NodeItem("GeometryNodeAttributeCompare"),
+        NodeItem("GeometryNodeAttributeConvert"),
         NodeItem("GeometryNodeAttributeFill"),
         NodeItem("GeometryNodeAttributeMix"),
         NodeItem("GeometryNodeAttributeProximity"),
diff --git a/source/blender/blenkernel/BKE_attribute.h b/source/blender/blenkernel/BKE_attribute.h
index 574d9904dc4..a98bfd1e3df 100644
--- a/source/blender/blenkernel/BKE_attribute.h
+++ b/source/blender/blenkernel/BKE_attribute.h
@@ -39,6 +39,7 @@ struct ReportList;
 
 /* Attribute.domain */
 typedef enum AttributeDomain {
+  ATTR_DOMAIN_AUTO = -1,   /* Use for nodes to choose automatically based on other data. */
   ATTR_DOMAIN_POINT = 0,   /* Mesh, Hair or PointCloud Point */
   ATTR_DOMAIN_EDGE = 1,    /* Mesh Edge */
   ATTR_DOMAIN_CORNER = 2,  /* Mesh Corner */
diff --git a/source/blender/blenkernel/BKE_node.h b/source/blender/blenkernel/BKE_node.h
index 2c543a0a014..0379dea9e8c 100644
--- a/source/blender/blenkernel/BKE_node.h
+++ b/source/blender/blenkernel/BKE_node.h
@@ -1373,6 +1373,7 @@ int ntreeTexExecTree(struct bNodeTree *ntree,
 #define GEO_NODE_ATTRIBUTE_SEPARATE_XYZ 1028
 #define GEO_NODE_SUBDIVIDE 1029
 #define GEO_NODE_ATTRIBUTE_REMOVE 1030
+#define GEO_NODE_ATTRIBUTE_CONVERT 1031
 
 /** \} */
 
diff --git a/source/blender/blenkernel/intern/node.cc b/source/blender/blenkernel/intern/node.cc
index 528088b2ee7..156f6a0c7ae 100644
--- a/source/blender/blenkernel/intern/node.cc
+++ b/source/blender/blenkernel/intern/node.cc
@@ -4788,6 +4788,7 @@ static void registerGeometryNodes()
   register_node_type_geo_attribute_color_ramp();
   register_node_type_geo_attribute_combine_xyz();
   register_node_type_geo_attribute_compare();
+  register_node_type_geo_attribute_convert();
   register_node_type_geo_attribute_fill();
   register_node_type_geo_attribute_math();
   register_node_type_geo_attribute_mix();
diff --git a/source/blender/makesdna/DNA_node_types.h b/source/blender/makesdna/DNA_node_types.h
index d19d270a7ac..ad1def0f3ec 100644
--- a/source/blender/makesdna/DNA_node_types.h
+++ b/source/blender/makesdna/DNA_node_types.h
@@ -1226,6 +1226,14 @@ typedef struct NodeAttributeSeparateXYZ {
   uint8_t input_type;
 } NodeAttributeSeparateXYZ;
 
+typedef struct NodeAttributeConvert {
+  /* CustomDataType. */
+  uint8_t data_type;
+  char _pad[1];
+  /* AttributeDomain. */
+  int16_t domain;
+} NodeAttributeConvert;
+
 /* script node mode */
 #define NODE_SCRIPT_INTERNAL 0
 #define NODE_SCRIPT_EXTERNAL 1
diff --git a/source/blender/makesrna/intern/rna_nodetree.c b/source/blender/makesrna/intern/rna_nodetree.c
index dfb882cde33..aed1b82e940 100644
--- a/source/blender/makesrna/intern/rna_nodetree.c
+++ b/source/blender/makesrna/intern/rna_nodetree.c
@@ -1929,6 +1929,23 @@ static void rna_GeometryNodeAttributeRandomize_data_type_update(Main *bmain,
   rna_Node_socket_update(bmain, scene, ptr);
 }
 
+static bool attribute_convert_type_supported(const EnumPropertyItem *item)
+{
+  return ELEM(item->value,
+              CD_PROP_FLOAT,
+              CD_PROP_FLOAT2,
+              CD_PROP_FLOAT3,
+              CD_PROP_COLOR,
+              CD_PROP_BOOL,
+              CD_PROP_INT32);
+}
+static const EnumPropertyItem *rna_GeometryNodeAttributeConvert_type_itemf(
+    bContext *UNUSED(C), PointerRNA *UNUSED(ptr), PropertyRNA *UNUSED(prop), bool *r_free)
+{
+  *r_free = true;
+  return itemf_function_check(rna_enum_attribute_type_items, attribute_convert_type_supported);
+}
+
 static bool attribute_fill_type_supported(const EnumPropertyItem *item)
 {
   return ELEM(
@@ -8647,6 +8664,35 @@ static void def_geo_attribute_fill(StructRNA *srna)
                                   "rna_GeometryNodeAttributeFill_domain_itemf");
 }
 
+static void def_geo_attribute_convert(StructRNA *srna)
+{
+  static const EnumPropertyItem rna_enum_attribute_convert_domain_items[] = {
+      {ATTR_DOMAIN_AUTO, "AUTO", 0, "Auto", ""},
+      {ATTR_DOMAIN_POINT, "POINT", 0, "Point", "Attribute on point"},
+      {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"},
+      {0, NULL, 0, NULL, NULL},
+  };
+
+  PropertyRNA *prop;
+
+  RNA_def_struct_sdna_from(srna, "NodeAttributeConvert", "storage");
+
+  prop = RNA_def_property(srna, "data_type", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_items(prop, rna_enum_attribute_type_items);
+  RNA_def_property_enum_funcs(prop, NULL, NULL, "rna_GeometryNodeAttributeConvert_type_itemf");
+  RNA_def_property_enum_default(prop, CD_PROP_FLOAT);
+  RNA_def_property_ui_text(prop, "Data Type", "The data type to save the result attribute with");
+  RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_GeometryNode_socket_update");
+
+  prop = RNA_def_property(srna, "domain", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_items(prop, rna_enum_attribute_convert_domain_items);
+  RNA_def_property_enum_default(prop, ATTR_DOMAIN_AUTO);
+  RNA_def_property_ui_text(prop, "Domain", "The geometry domain to save the result attribute in");
+  RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_Node_update");
+}
+
 static void def_geo_attribute_math(StructRNA *srna)
 {
   PropertyRNA *prop;
diff --git a/source/blender/nodes/CMakeLists.txt b/source/blender/nodes/CMakeLists.txt
index 9408e5348dd..bbc14751cdd 100644
--- a/source/blender/nodes/CMakeLists.txt
+++ b/source/blender/nodes/CMakeLists.txt
@@ -146,6 +146,7 @@ set(SRC
   geometry/nodes/node_geo_attribute_color_ramp.cc
   geometry/nodes/node_geo_attribute_combine_xyz.cc
   geometry/nodes/node_geo_attribute_compare.cc
+  geometry/nodes/node_geo_attribute_convert.cc
   geometry/nodes/node_geo_attribute_fill.cc
   geometry/nodes/node_geo_attribute_math.cc
   geometry/nodes/node_geo_attribute_mix.cc
diff --git a/source/blender/nodes/NOD_geometry.h b/source/blender/nodes/NOD_geometry.h
index d7f56464b36..d28dc8209d4 100644
--- a/source/blender/nodes/NOD_geometry.h
+++ b/source/blender/nodes/NOD_geometry.h
@@ -30,6 +30,7 @@ void register_node_type_geo_align_rotation_to_vector(void);
 void register_node_type_geo_attribute_color_ramp(void);
 void register_node_type_geo_attribute_combine_xyz(void);
 void register_node_type_geo_attribute_compare(void);
+void register_node_type_geo_attribute_convert(void);
 void register_node_type_geo_attribute_fill(void);
 void register_node_type_geo_attribute_math(void);
 void register_node_type_geo_attribute_mix(void);
diff --git a/source/blender/nodes/NOD_static_types.h b/source/blender/nodes/NOD_static_types.h
index 6669f47c6aa..493aaa05675 100644
--- a/source/blender/nodes/NOD_static_types.h
+++ b/source/blender/nodes/NOD_static_types.h
@@ -300,6 +300,7 @@ DefNode(GeometryNode, GEO_NODE_ATTRIBUTE_COMBINE_XYZ, def_geo_attribute_combine_
 DefNode(GeometryNode, GEO_NODE_ATTRIBUTE_SEPARATE_XYZ, def_geo_attribute_separate_xyz, "ATTRIBUTE_SEPARATE_XYZ", AttributeSeparateXYZ, "Attribute Separate XYZ", "")
 DefNode(GeometryNode, GEO_NODE_SUBDIVIDE, 0, "SUBDIVIDE", Subdivide, "Subdivide", "")
 DefNode(GeometryNode, GEO_NODE_ATTRIBUTE_REMOVE, 0, "ATTRIBUTE_REMOVE", AttributeRemove, "Attribute Remove", "")
+DefNode(GeometryNode, GEO_NODE_ATTRIBUTE_CONVERT, def_geo_attribute_convert, "ATTRIBUTE_CONVERT", AttributeConvert, "Attribute Convert", "")
 
 /* undefine macros */
 #undef DefNode
diff --git a/source/blender/nodes/geometry/nodes/node_geo_attribute_convert.cc b/source/blender/nodes/geometry/nodes/node_geo_attribute_convert.cc
new file mode 100644
index 00000000000..11d220dd903
--- /dev/null
+++ b/source/blender/nodes/geometry/nodes/node_geo_attribute_convert.cc
@@ -0,0 +1,164 @@
+/*
+ * 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.
+ */
+
+#include "node_geometry_util.hh"
+
+#include "UI_interface.h"
+#include "UI_resources.h"
+
+static bNodeSocketTemplate geo_node_attribute_convert_in[] = {
+    {SOCK_GEOMETRY, N_("Geometry")},
+    {SOCK_STRING, N_("Attribute")},
+    {SOCK_STRING, N_("Result")},
+    {-1, ""},
+};
+
+static bNodeSocketTemplate geo_node_attribute_convert_out[] = {
+    {SOCK_GEOMETRY, N_("Geometry")},
+    {-1, ""},
+};
+
+static void geo_node_attribute_convert_layout(uiLayout *layout,
+                                              bContext *UNUSED(C),
+                                              PointerRNA *ptr)
+{
+  uiItemR(layout, ptr, "domain", 0, "", ICON_NONE);
+  uiItemR(layout, ptr, "data_type", 0, "", ICON_NONE);
+}
+
+static void geo_node_attribute_convert_init(bNodeTree *UNUSED(tree), bNode *node)
+{
+  NodeAttributeConvert *data = (NodeAttributeConvert *)MEM_callocN(sizeof(NodeAttributeConvert),
+                                                                   __func__);
+
+  data->data_type = CD_PROP_FLOAT;
+  data->domain = ATTR_DOMAIN_AUTO;
+  node->storage = data;
+}
+
+namespace blender::nodes {
+
+static AttributeDomain get_result_domain(const GeometryComponent &component,
+                                         StringRef source_name,
+                                         StringRef result_name)
+{
+  ReadAttributePtr result_attribute = component.attribute_try_get_for_read(result_name);
+  if (result_attribute) {
+    return result_attribute->domain();
+  }
+  ReadAttributePtr source_attribute = component.attribute_try_get_for_read(source_name);
+  if (source_attribute) {
+    return source_attribute->domain();
+  }
+  return ATTR_DOMAIN_POINT;
+}
+
+static void attribute_convert_calc(GeometryComponent &component,
+                                   const GeoNodeExecParams &params,
+                                   const StringRef source_name,
+                                   const StringRef result_name,
+                                   const CustomDataType result_type,
+                                   const AttributeDomain domain)
+{
+  const AttributeDomain result_domain = (domain == ATTR_DOMAIN_AUTO) ?
+                                            get_result_domain(
+                                                component, source_name, result_name) :
+                                            domain;
+
+  ReadAttributePtr source_attribute = component.attribute_try_get_for_read(
+      source_name, result_domain, result_type);
+  if (!source_attribute) {
+    params.error_message_add(NodeWarningType::Error,
+                             TIP_("No attribute with name \"") + source_name + "\"");
+    return;
+  }
+
+  OutputAttributePtr result_attribute = component.attribute_try_get_for_output(
+      result_name, result_domain, result_type);
+  if (!result_attribute) {
+    return;
+  }
+
+  fn::GSpan source_span = source_attribute->get_span();
+  fn::GMutableSpan result_span = result_attribute->get_span_for_write_only();
+  if (source_span.is_empty() || result_span.is_empty()) {
+    return;
+  }
+  BLI_assert(source_span.size() == result_span.size());
+
+  const CPPType *cpp_type = bke::custom_data_type_to_cpp_type(result_type);
+  BLI_assert(cpp_type != nullptr);
+
+  cpp_type->copy_to_initialized_n(source_span.data(), result_span.data(), result_span.size());
+
+  result_attribute.apply_span_and_save();
+}
+
+static void geo_node_attribute_convert_exec(GeoNodeExecParams params)
+{
+  GeometrySet geometry_set = params.extract_input<GeometrySet>("Geometry");
+
+  geometry_set = geometry_set_realize_instances(geometry_set);
+
+  const std::string result_name = params.extract_input<std::string>("Result");
+  const std::string source_name = params.extract_input<std::string>("Attribute");
+  const NodeAttributeConvert &node_storage = *(const NodeAttributeConvert *)params.node().storage;
+  const CustomDataType data_type = static_cast<CustomDataType>(node_storage.data_type);
+  const AttributeDomain domain = static_cast<AttributeDomain>(node_storage.domain);
+
+  if (result_name.empty()) {
+    params.set_output("Geometry", geometry_set);
+    return;
+  }
+
+  if (geometry_set.has<MeshComponent>()) {
+    attribute_convert_calc(geometry_set.get_component_for_write<MeshComponent>(),
+                           params,
+                           source_name,
+                           result_name,
+                           data_type,
+                           domain);
+  }
+  if (geometry_set.has<PointCloudComponent>()) {
+    attribute_convert_calc(geometry_set.get_component_for_write<PointCloudComponent>(),
+                           params,
+                           source_name,
+                           result_name,
+                           data_type,
+                           domain);
+  }
+
+  params.set_output("Geometry", geometry_set);
+}
+
+}  // namespace blender::nodes
+
+void register_node_type_geo_attribute_convert()
+{
+  static bNodeType ntype;
+
+  geo_node_type_base(
+      &ntype, GEO_NODE_ATTRIBUTE_CONVERT, "Attribute Convert", NODE_CLASS_ATTRIBUTE, 0);
+  node_type_socket_templates(
+      &ntype, geo_node_attribute_convert_in, geo_node_attribute_convert_out);
+  ntype.geometry_node_execute = blender::nodes::geo_node_attribute_convert_exec;
+  ntype.draw_buttons = geo_node_attribute_convert_layout;
+  node_type_init(&ntype, geo_node_attribute_convert_init);
+  node_type_storage(
+      &ntype, "NodeAttributeConvert", node_free_standard_storage, node_copy_standard_storage);
+
+  nodeRegisterType(&ntype);
+}