Geometry Nodes: Support instances in attribute search

Previously only attributes of "real" geometry were displayed in
attribute search. This commit adds code to look through attributes
on instances and add those to the search drop-down too.

This required implementing the same sort of recursive traversal as
the realize instances code. The situation is a bit different though,
this can return early and doesn't need to keep track of transforms.

I added a limit so that it doesn't look through the attributes of
too many instanced geometry sets. I think this is important, since
this isn't a trivial operation and it could potentially happen for
every node in a large node tree. Currently the limit is set at 8
geometry sets, which I expect will be enough, since the set of
attributes is mostly not very unique anyway.

Fixes T86282

Diffrential Revision: https://developer.blender.org/D10919

1 files changed, 10 insertions, 4 deletions

diff --git a/source/blender/blenkernel/intern/attribute_access.cc b/source/blender/blenkernel/intern/attribute_access.cc
index 52f89ca302b..5bd3b990a63 100644
--- a/source/blender/blenkernel/intern/attribute_access.cc
+++ b/source/blender/blenkernel/intern/attribute_access.cc
@@ -822,12 +822,16 @@ Set<std::string> GeometryComponent::attribute_names() const
   return attributes;
 }
 
-void GeometryComponent::attribute_foreach(const AttributeForeachCallback callback) const
+/**
+ * \return False if the callback explicitly returned false at any point, otherwise true,
+ * meaning the callback made it all the way through.
+ */
+bool GeometryComponent::attribute_foreach(const AttributeForeachCallback callback) const
 {
   using namespace blender::bke;
   const ComponentAttributeProviders *providers = this->get_attribute_providers();
   if (providers == nullptr) {
-    return;
+    return true;
   }
 
   /* Keep track handled attribute names to make sure that we do not return the same name twice. */
@@ -838,7 +842,7 @@ void GeometryComponent::attribute_foreach(const AttributeForeachCallback callbac
     if (provider->exists(*this)) {
       AttributeMetaData meta_data{provider->domain(), provider->data_type()};
       if (!callback(provider->name(), meta_data)) {
-        return;
+        return false;
       }
       handled_attribute_names.add_new(provider->name());
     }
@@ -852,9 +856,11 @@ void GeometryComponent::attribute_foreach(const AttributeForeachCallback callbac
           return true;
         });
     if (!continue_loop) {
-      return;
+      return false;
     }
   }
+
+  return true;
 }
 
 bool GeometryComponent::attribute_exists(const blender::StringRef attribute_name) const