Geometry Nodes: improve accessing attribute meta data

This allows accessing attribute meta data like domain and data type
without having to create a `ReadAttribute`. I kept the `attribute_names`
method for now to keep the patch more self contained.

Differential Revision: https://developer.blender.org/D10511

1 files changed, 17 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_geometry_set.hh b/source/blender/blenkernel/BKE_geometry_set.hh
index 5b1882d0d4c..ad01814ce82 100644
--- a/source/blender/blenkernel/BKE_geometry_set.hh
+++ b/source/blender/blenkernel/BKE_geometry_set.hh
@@ -25,6 +25,7 @@
 
 #include "BLI_float3.hh"
 #include "BLI_float4x4.hh"
+#include "BLI_function_ref.hh"
 #include "BLI_hash.hh"
 #include "BLI_map.hh"
 #include "BLI_set.hh"
@@ -129,6 +130,20 @@ class OutputAttributePtr {
 };
 
 /**
+ * Contains information about an attribute in a geometry component.
+ * More information can be added in the future. E.g. whether the attribute is builtin and how it is
+ * stored (uv map, vertex group, ...).
+ */
+struct AttributeMetaData {
+  AttributeDomain domain;
+  CustomDataType data_type;
+};
+
+/* Returns false when the iteration should be stopped. */
+using AttributeForeachCallback = blender::FunctionRef<bool(blender::StringRefNull attribute_name,
+                                                           const AttributeMetaData &meta_data)>;
+
+/**
  * This is the base class for specialized geometry component types.
  */
 class GeometryComponent {
@@ -185,6 +200,8 @@ class GeometryComponent {
                             const CustomDataType data_type);
 
   blender::Set<std::string> attribute_names() const;
+  void attribute_foreach(const AttributeForeachCallback callback) const;
+
   virtual bool is_empty() const;
 
   /* Get a read-only attribute for the given domain and data type.