Geometry Nodes: Propagate attributes in Instances to Points node

This is part of T92926, and is very similar to 221b7b27fce3, except
slightly similar, because it only transfers from one component, and
it doesn't handle multi-threading at the moment.

1 files changed, 28 insertions, 9 deletions

diff --git a/source/blender/nodes/geometry/nodes/node_geo_instances_to_points.cc b/source/blender/nodes/geometry/nodes/node_geo_instances_to_points.cc
index 30aa745ddff..536facbc2e5 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_instances_to_points.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_instances_to_points.cc
@@ -14,9 +14,11 @@
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */
 
-#include "BKE_pointcloud.h"
 #include "DNA_pointcloud_types.h"
 
+#include "BKE_attribute_math.hh"
+#include "BKE_pointcloud.h"
+
 #include "node_geometry_util.hh"
 
 namespace blender::nodes::node_geo_instances_to_points_cc {
@@ -76,14 +78,31 @@ static void convert_instances_to_points(GeometrySet &geometry_set,
   const VArray<float> &radii = evaluator.get_evaluated<float>(1);
   copy_attribute_to_points(radii, selection, {pointcloud->radius, pointcloud->totpoint});
 
-  if (!instances.instance_ids().is_empty()) {
-    OutputAttribute_Typed<int> id_attribute = points.attribute_try_get_for_output<int>(
-        "id", ATTR_DOMAIN_POINT, CD_PROP_INT32);
-    MutableSpan<int> ids = id_attribute.as_span();
-    for (const int i : selection.index_range()) {
-      ids[i] = instances.instance_ids()[selection[i]];
-    }
-    id_attribute.save();
+  Map<AttributeIDRef, AttributeKind> attributes_to_propagate;
+  geometry_set.gather_attributes_for_propagation({GEO_COMPONENT_TYPE_INSTANCES},
+                                                 GEO_COMPONENT_TYPE_POINT_CLOUD,
+                                                 false,
+                                                 attributes_to_propagate);
+  /* These two attributes are added by the implicit inputs above. */
+  attributes_to_propagate.remove("position");
+  attributes_to_propagate.remove("radius");
+
+  for (const auto &item : attributes_to_propagate.items()) {
+    const AttributeIDRef &attribute_id = item.key;
+    const AttributeKind attribute_kind = item.value;
+
+    const GVArray src = instances.attribute_get_for_read(
+        attribute_id, ATTR_DOMAIN_INSTANCE, attribute_kind.data_type);
+    BLI_assert(src);
+    OutputAttribute dst = points.attribute_try_get_for_output_only(
+        attribute_id, ATTR_DOMAIN_POINT, attribute_kind.data_type);
+    BLI_assert(dst);
+
+    attribute_math::convert_to_static_type(attribute_kind.data_type, [&](auto dummy) {
+      using T = decltype(dummy);
+      copy_attribute_to_points(src.typed<T>(), selection, dst.as_span().typed<T>());
+    });
+    dst.save();
   }
 }