Geometry Nodes: Add a toggle to use attributes as input values

This adds a toggle to node group inputs exposed in the modifier to use
an attribute instead of a single value. When the toggle is pressed, the
button switches to a text button to choose an attribute name. Attribute
search isn't implemented here yet.

One confusing thing is that some values can't be driven by attributes
at all, like the size of a primitive node. In that case, we should have
a node warning, but that will be separate since it's more general.
We can also have an option to turn off this toggle in node group
input settings.

The two new properties for each input are stored with the same name
as the value, but with `"_use_attribute"` and `"_attribute_name"``
suffixes. The properties are not added for socket types that don't
support attribute input, like object sockets.

Differential Revision: https://developer.blender.org/D12504

3 files changed, 53 insertions, 0 deletions

diff --git a/source/blender/editors/object/object_intern.h b/source/blender/editors/object/object_intern.h
index b2d3216b101..50dd9322c5c 100644
--- a/source/blender/editors/object/object_intern.h
+++ b/source/blender/editors/object/object_intern.h
@@ -191,6 +191,7 @@ void OBJECT_OT_skin_radii_equalize(struct wmOperatorType *ot);
 void OBJECT_OT_skin_armature_create(struct wmOperatorType *ot);
 void OBJECT_OT_laplaciandeform_bind(struct wmOperatorType *ot);
 void OBJECT_OT_surfacedeform_bind(struct wmOperatorType *ot);
+void OBJECT_OT_geometry_nodes_input_attribute_toggle(struct wmOperatorType *ot);
 
 /* object_gpencil_modifiers.c */
 void OBJECT_OT_gpencil_modifier_add(struct wmOperatorType *ot);
diff --git a/source/blender/editors/object/object_modifier.c b/source/blender/editors/object/object_modifier.c
index 2a1a6696493..b9942bc563a 100644
--- a/source/blender/editors/object/object_modifier.c
+++ b/source/blender/editors/object/object_modifier.c
@@ -3242,3 +3242,54 @@ void OBJECT_OT_surfacedeform_bind(wmOperatorType *ot)
 }
 
 /** \} */
+
+/* ------------------------------------------------------------------- */
+/** \name Toggle Value or Attribute Operator
+ *
+ * \note This operator basically only exists to provide a better tooltip for the toggle button,
+ * since it is stored as an IDProperty. It also stops the button from being highlighted when
+ * "use_attribute" is on, which isn't expected.
+ * \{ */
+
+static int geometry_nodes_input_attribute_toggle_exec(bContext *C, wmOperator *op)
+{
+  Object *ob = ED_object_active_context(C);
+
+  char modifier_name[MAX_NAME];
+  RNA_string_get(op->ptr, "modifier_name", modifier_name);
+  NodesModifierData *nmd = (NodesModifierData *)BKE_modifiers_findby_name(ob, modifier_name);
+  if (nmd == NULL) {
+    return OPERATOR_CANCELLED;
+  }
+
+  char prop_path[MAX_NAME];
+  RNA_string_get(op->ptr, "prop_path", prop_path);
+
+  PointerRNA mod_ptr;
+  RNA_pointer_create(&ob->id, &RNA_Modifier, nmd, &mod_ptr);
+
+  const int old_value = RNA_int_get(&mod_ptr, prop_path);
+  const int new_value = !old_value;
+  RNA_int_set(&mod_ptr, prop_path, new_value);
+
+  DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
+  WM_event_add_notifier(C, NC_OBJECT | ND_MODIFIER, ob);
+  return OPERATOR_FINISHED;
+}
+
+void OBJECT_OT_geometry_nodes_input_attribute_toggle(wmOperatorType *ot)
+{
+  ot->name = "Input Attribute Toggle";
+  ot->description =
+      "Switch between an attribute and a single value to define the data for every element";
+  ot->idname = "OBJECT_OT_geometry_nodes_input_attribute_toggle";
+
+  ot->exec = geometry_nodes_input_attribute_toggle_exec;
+
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_INTERNAL;
+
+  RNA_def_string(ot->srna, "prop_path", NULL, 0, "Prop Path", "");
+  RNA_def_string(ot->srna, "modifier_name", NULL, MAX_NAME, "Modifier Name", "");
+}
+
+/** \} */
diff --git a/source/blender/editors/object/object_ops.c b/source/blender/editors/object/object_ops.c
index 4b8431be530..aa9ae082317 100644
--- a/source/blender/editors/object/object_ops.c
+++ b/source/blender/editors/object/object_ops.c
@@ -145,6 +145,7 @@ void ED_operatortypes_object(void)
   WM_operatortype_append(OBJECT_OT_skin_loose_mark_clear);
   WM_operatortype_append(OBJECT_OT_skin_radii_equalize);
   WM_operatortype_append(OBJECT_OT_skin_armature_create);
+  WM_operatortype_append(OBJECT_OT_geometry_nodes_input_attribute_toggle);
 
   /* grease pencil modifiers */
   WM_operatortype_append(OBJECT_OT_gpencil_modifier_add);