Geometry Nodes: Get and set nodes for ID attribute

These nodes allow accessing and changing the stable/random ID used
for motion blur with instances and stable randomness.

Since rB40c3b8836b7a, the stable ID is a built-in attribute, so to be
consistent and allow changing it in the node tree like other built-in
attributes, it has get and set nodes.

release/scripts/startup/nodeitems_builtins.py

@@ -157,6 +157,34 @@ def mesh_node_items(context):
     yield NodeItemCustom(draw=lambda self, layout, context: layout.separator())
     yield NodeItem("GeometryNodeSetShadeSmooth")
 
+# Custom Menu for Geometry Nodes "Geometry" category
+def geometry_node_items(context):
+    if context is None:
+        return
+    space = context.space_data
+    if not space:
+        return
+    if not space.edit_tree:
+        return
+
+    if geometry_nodes_legacy_poll(context):
+        yield NodeItem("GeometryNodeLegacyDeleteGeometry", poll=geometry_nodes_legacy_poll)
+        yield NodeItem("GeometryNodeLegacyRaycast", poll=geometry_nodes_legacy_poll)
+        yield NodeItemCustom(draw=lambda self, layout, context: layout.separator())
+
+    yield NodeItem("GeometryNodeBoundBox")
+    yield NodeItem("GeometryNodeConvexHull")
+    yield NodeItem("GeometryNodeDeleteGeometry")
+    yield NodeItem("GeometryNodeProximity")
+    yield NodeItem("GeometryNodeJoinGeometry")
+    yield NodeItem("GeometryNodeRaycast")
+    yield NodeItem("GeometryNodeSeparateComponents")
+    yield NodeItem("GeometryNodeSeparateGeometry")
+    yield NodeItem("GeometryNodeTransform")
+    yield NodeItemCustom(draw=lambda self, layout, context: layout.separator())
+    yield NodeItem("GeometryNodeSetID")
+    yield NodeItem("GeometryNodeSetPosition")
+
 # Custom Menu for Geometry Node Input Nodes
 def geometry_input_node_items(context):
     if context is None:
@@ -182,6 +210,7 @@ def geometry_input_node_items(context):
     yield NodeItem("ShaderNodeValue")
     yield NodeItem("FunctionNodeInputVector")
     yield NodeItemCustom(draw=lambda self, layout, context: layout.separator())
+    yield NodeItem("GeometryNodeInputID")
     yield NodeItem("GeometryNodeInputIndex")
     yield NodeItem("GeometryNodeInputNormal")
     yield NodeItem("GeometryNodeInputPosition")
@@ -677,21 +706,7 @@ geometry_node_categories = [
         NodeItem("GeometryNodeCurvePrimitiveQuadrilateral"),
         NodeItem("GeometryNodeCurvePrimitiveBezierSegment"),
     ]),
-    GeometryNodeCategory("GEO_GEOMETRY", "Geometry", items=[
-        NodeItem("GeometryNodeLegacyDeleteGeometry", poll=geometry_nodes_legacy_poll),
-        NodeItem("GeometryNodeLegacyRaycast", poll=geometry_nodes_legacy_poll),
-
-        NodeItem("GeometryNodeRaycast"),
-        NodeItem("GeometryNodeProximity"),
-        NodeItem("GeometryNodeBoundBox"),
-        NodeItem("GeometryNodeConvexHull"),
-        NodeItem("GeometryNodeDeleteGeometry"),
-        NodeItem("GeometryNodeTransform"),
-        NodeItem("GeometryNodeJoinGeometry"),
-        NodeItem("GeometryNodeSeparateComponents"),
-        NodeItem("GeometryNodeSeparateGeometry"),
-        NodeItem("GeometryNodeSetPosition"),
-    ]),
+    GeometryNodeCategory("GEO_GEOMETRY", "Geometry", items=geometry_node_items),
     GeometryNodeCategory("GEO_INPUT", "Input", items=geometry_input_node_items),
     GeometryNodeCategory("GEO_INSTANCE", "Instances", items=[
         NodeItem("GeometryNodeInstanceOnPoints"),

source/blender/blenkernel/BKE_node.h

@@ -1549,6 +1549,8 @@ int ntreeTexExecTree(struct bNodeTree *ntree,
 #define GEO_NODE_INSTANCES_TO_POINTS 1131
 #define GEO_NODE_IMAGE_TEXTURE 1132
 #define GEO_NODE_VOLUME_TO_MESH 1133
+#define GEO_NODE_INPUT_ID 1134
+#define GEO_NODE_SET_ID 1135
 
 /** \} */
 

source/blender/blenkernel/intern/node.cc

@@ -5804,6 +5804,7 @@ static void registerGeometryNodes()
   register_node_type_geo_image_texture();
   register_node_type_geo_input_curve_handles();
   register_node_type_geo_input_curve_tilt();
+  register_node_type_geo_input_id();
   register_node_type_geo_input_index();
   register_node_type_geo_input_material_index();
   register_node_type_geo_input_material();
@@ -5852,6 +5853,7 @@ static void registerGeometryNodes()
   register_node_type_geo_set_curve_handles();
   register_node_type_geo_set_curve_radius();
   register_node_type_geo_set_curve_tilt();
+  register_node_type_geo_set_id();
   register_node_type_geo_set_material_index();
   register_node_type_geo_set_material();
   register_node_type_geo_set_point_radius();

source/blender/nodes/CMakeLists.txt

@@ -231,6 +231,7 @@ set(SRC
   geometry/nodes/node_geo_image_texture.cc
   geometry/nodes/node_geo_input_curve_handles.cc
   geometry/nodes/node_geo_input_curve_tilt.cc
+  geometry/nodes/node_geo_input_id.cc
   geometry/nodes/node_geo_input_index.cc
   geometry/nodes/node_geo_input_material_index.cc
   geometry/nodes/node_geo_input_material.cc
@@ -272,6 +273,7 @@ set(SRC
   geometry/nodes/node_geo_set_curve_handles.cc
   geometry/nodes/node_geo_set_curve_radius.cc
   geometry/nodes/node_geo_set_curve_tilt.cc
+  geometry/nodes/node_geo_set_id.cc
   geometry/nodes/node_geo_set_material_index.cc
   geometry/nodes/node_geo_set_material.cc
   geometry/nodes/node_geo_set_point_radius.cc

source/blender/nodes/NOD_geometry.h

@@ -98,6 +98,7 @@ void register_node_type_geo_edge_split(void);
 void register_node_type_geo_image_texture(void);
 void register_node_type_geo_input_curve_handles(void);
 void register_node_type_geo_input_curve_tilt(void);
+void register_node_type_geo_input_id(void);
 void register_node_type_geo_input_index(void);
 void register_node_type_geo_input_material_index(void);
 void register_node_type_geo_input_material(void);
@@ -147,6 +148,7 @@ void register_node_type_geo_separate_geometry(void);
 void register_node_type_geo_set_curve_handles(void);
 void register_node_type_geo_set_curve_radius(void);
 void register_node_type_geo_set_curve_tilt(void);
+void register_node_type_geo_set_id(void);
 void register_node_type_geo_set_material_index(void);
 void register_node_type_geo_set_material(void);
 void register_node_type_geo_set_point_radius(void);

source/blender/nodes/NOD_static_types.h

@@ -351,6 +351,7 @@ DefNode(GeometryNode, GEO_NODE_FILLET_CURVE, def_geo_curve_fillet, "FILLET_CURVE
 DefNode(GeometryNode, GEO_NODE_IMAGE_TEXTURE, def_geo_image_texture, "IMAGE_TEXTURE", ImageTexture, "Image Texture", "")
 DefNode(GeometryNode, GEO_NODE_INPUT_CURVE_HANDLES, 0, "INPUT_CURVE_HANDLES", InputCurveHandlePositions, "Curve Handle Positions", "")
 DefNode(GeometryNode, GEO_NODE_INPUT_CURVE_TILT, 0, "INPUT_CURVE_TILT", InputCurveTilt, "Curve Tilt", "")
+DefNode(GeometryNode, GEO_NODE_INPUT_ID, 0, "INPUT_ID", InputID, "ID", "")
 DefNode(GeometryNode, GEO_NODE_INPUT_INDEX, 0, "INDEX", InputIndex, "Index", "")
 DefNode(GeometryNode, GEO_NODE_INPUT_MATERIAL_INDEX, 0, "INPUT_MATERIAL_INDEX", InputMaterialIndex, "Material Index", "")
 DefNode(GeometryNode, GEO_NODE_INPUT_MATERIAL, def_geo_input_material, "INPUT_MATERIAL", InputMaterial, "Material", "")
@@ -395,6 +396,7 @@ DefNode(GeometryNode, GEO_NODE_SEPARATE_GEOMETRY, def_geo_separate_geometry, "SE
 DefNode(GeometryNode, GEO_NODE_SET_CURVE_HANDLES, def_geo_curve_set_handle_positions, "SET_CURVE_HANDLES", SetCurveHandlePositions, "Set Handle Positions", "")
 DefNode(GeometryNode, GEO_NODE_SET_CURVE_RADIUS, 0, "SET_CURVE_RADIUS", SetCurveRadius, "Set Curve Radius", "")
 DefNode(GeometryNode, GEO_NODE_SET_CURVE_TILT, 0, "SET_CURVE_TILT", SetCurveTilt, "Set Curve Tilt", "")
+DefNode(GeometryNode, GEO_NODE_SET_ID, 0, "SET_ID", SetID, "Set ID", "")
 DefNode(GeometryNode, GEO_NODE_SET_MATERIAL_INDEX, 0, "SET_MATERIAL_INDEX", SetMaterialIndex, "Set Material Index", "")
 DefNode(GeometryNode, GEO_NODE_SET_MATERIAL, 0, "SET_MATERIAL", SetMaterial, "Set Material", "")
 DefNode(GeometryNode, GEO_NODE_SET_POINT_RADIUS, 0, "SET_POINT_RADIUS", SetPointRadius, "Set Point Radius", "")

source/blender/nodes/geometry/nodes/node_geo_input_id.cc

@@ -0,0 +1,42 @@
+/*
+ * 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"
+
+namespace blender::nodes {
+
+static void geo_node_input_id_declare(NodeDeclarationBuilder &b)
+{
+  b.add_output<decl::Int>("ID").field_source();
+}
+
+static void geo_node_input_id_exec(GeoNodeExecParams params)
+{
+  Field<int> position_field{AttributeFieldInput::Create<int>("id")};
+  params.set_output("ID", std::move(position_field));
+}
+
+}  // namespace blender::nodes
+
+void register_node_type_geo_input_id()
+{
+  static bNodeType ntype;
+
+  geo_node_type_base(&ntype, GEO_NODE_INPUT_ID, "ID", NODE_CLASS_INPUT, 0);
+  ntype.geometry_node_execute = blender::nodes::geo_node_input_id_exec;
+  ntype.declare = blender::nodes::geo_node_input_id_declare;
+  nodeRegisterType(&ntype);
+}

source/blender/nodes/geometry/nodes/node_geo_set_id.cc

@@ -0,0 +1,94 @@
+/*
+ * 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"
+
+namespace blender::nodes {
+
+static void geo_node_set_id_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Geometry>("Geometry");
+  b.add_input<decl::Bool>("Selection").default_value(true).hide_value().supports_field();
+  b.add_input<decl::Int>("ID").supports_field();
+  b.add_output<decl::Geometry>("Geometry");
+}
+
+static void set_id_in_component(GeometryComponent &component,
+                                const Field<bool> &selection_field,
+                                const Field<int> &id_field)
+{
+  GeometryComponentFieldContext field_context{component, ATTR_DOMAIN_POINT};
+  const int domain_size = component.attribute_domain_size(ATTR_DOMAIN_POINT);
+  if (domain_size == 0) {
+    return;
+  }
+
+  fn::FieldEvaluator selection_evaluator{field_context, domain_size};
+  selection_evaluator.add(selection_field);
+  selection_evaluator.evaluate();
+  const IndexMask selection = selection_evaluator.get_evaluated_as_mask(0);
+
+  /* Since adding the ID attribute can change the result of the field evaluation (the random value
+   * node uses the index if the ID is unavailable), make sure that it isn't added before evaluating
+   * the field. However, as an optimization, use a faster code path when it already exists. */
+  fn::FieldEvaluator id_evaluator{field_context, &selection};
+  if (component.attribute_exists("id")) {
+    OutputAttribute_Typed<int> id_attribute = component.attribute_try_get_for_output_only<int>(
+        "id", ATTR_DOMAIN_POINT);
+    id_evaluator.add_with_destination(id_field, id_attribute.varray());
+    id_evaluator.evaluate();
+    id_attribute.save();
+  }
+  else {
+    id_evaluator.add(id_field);
+    id_evaluator.evaluate();
+    const VArray<int> &result_ids = id_evaluator.get_evaluated<int>(0);
+    OutputAttribute_Typed<int> id_attribute = component.attribute_try_get_for_output_only<int>(
+        "id", ATTR_DOMAIN_POINT);
+    result_ids.materialize(selection, id_attribute.as_span());
+    id_attribute.save();
+  }
+}
+
+static void geo_node_set_id_exec(GeoNodeExecParams params)
+{
+  GeometrySet geometry_set = params.extract_input<GeometrySet>("Geometry");
+  Field<bool> selection_field = params.extract_input<Field<bool>>("Selection");
+  Field<int> id_field = params.extract_input<Field<int>>("ID");
+
+  for (const GeometryComponentType type : {GEO_COMPONENT_TYPE_INSTANCES,
+                                           GEO_COMPONENT_TYPE_MESH,
+                                           GEO_COMPONENT_TYPE_POINT_CLOUD,
+                                           GEO_COMPONENT_TYPE_CURVE}) {
+    if (geometry_set.has(type)) {
+      set_id_in_component(geometry_set.get_component_for_write(type), selection_field, id_field);
+    }
+  }
+
+  params.set_output("Geometry", std::move(geometry_set));
+}
+
+}  // namespace blender::nodes
+
+void register_node_type_geo_set_id()
+{
+  static bNodeType ntype;
+
+  geo_node_type_base(&ntype, GEO_NODE_SET_ID, "Set ID", NODE_CLASS_GEOMETRY, 0);
+  ntype.geometry_node_execute = blender::nodes::geo_node_set_id_exec;
+  ntype.declare = blender::nodes::geo_node_set_id_declare;
+  nodeRegisterType(&ntype);
+}