Geometry Nodes: support creating new attributes in modifier

This patch allows passing a field to the modifier as output. In the
modifier, the user can choose an attribute name. The attribute
will be filled with values computed by the field. This only works
for realized mesh/curve/point data. As mentioned in T91376, the
output domain is selected in the node group itself. We might want
to add this functionality to the modifier later as well, but not now.

Differential Revision: https://developer.blender.org/D12644

1 files changed, 4 insertions, 1 deletions

diff --git a/source/blender/makesdna/DNA_node_types.h b/source/blender/makesdna/DNA_node_types.h
index 38f38b4ba1e..34c74e5bd88 100644
--- a/source/blender/makesdna/DNA_node_types.h
+++ b/source/blender/makesdna/DNA_node_types.h
@@ -120,7 +120,10 @@ typedef struct bNodeSocket {
   /* XXX deprecated, kept for forward compatibility */
   short stack_type DNA_DEPRECATED;
   char display_shape;
-  char _pad[1];
+
+  /* #AttributeDomain used when the geometry nodes modifier creates an attribute for a group
+   * output. */
+  char attribute_domain;
   /* Runtime-only cache of the number of input links, for multi-input sockets. */
   short total_inputs;