Fix T97595: Modifier attribute output broken for vertex groups

`attribute_try_create` didn't understand that the vertex group
attribute already existed because it only looks for names in custom
data layers when the domain matches. Using `attribute_exists`
unfortunately requires another loop through all attribute names,
but that should be optimized separately in the future anyway.

Differential Revision: https://developer.blender.org/D14756

1 files changed, 3 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/attribute_access.cc b/source/blender/blenkernel/intern/attribute_access.cc
index 77c7857a528..98db5013a00 100644
--- a/source/blender/blenkernel/intern/attribute_access.cc
+++ b/source/blender/blenkernel/intern/attribute_access.cc
@@ -939,6 +939,9 @@ bool GeometryComponent::attribute_try_create(const AttributeIDRef &attribute_id,
   if (providers == nullptr) {
     return false;
   }
+  if (this->attribute_exists(attribute_id)) {
+    return false;
+  }
   if (attribute_id.is_named()) {
     const BuiltinAttributeProvider *builtin_provider =
         providers->builtin_attribute_providers().lookup_default_as(attribute_id.name(), nullptr);