Fix T55956: Transfer Weights: Source Layers can't be set to Active Layer.

Behavior of source/destination options was rather flaky in reversed
mode...

Note that even though this mode is a bit annoying and cumbersome, the
only alternative (defining a specific transfer weight operator) would be
much more verbose, so think that for now we'd rather keep what we have
here.

1 files changed, 23 insertions, 11 deletions

diff --git a/source/blender/editors/object/object_data_transfer.c b/source/blender/editors/object/object_data_transfer.c
index 3e32770c9a8..52b60793585 100644
--- a/source/blender/editors/object/object_data_transfer.c
+++ b/source/blender/editors/object/object_data_transfer.c
@@ -88,19 +88,28 @@ static const EnumPropertyItem DT_layer_items[] = {
 static const EnumPropertyItem *dt_layers_select_src_itemf(
         bContext *C, PointerRNA *ptr, PropertyRNA *UNUSED(prop), bool *r_free)
 {
-	EnumPropertyItem *item = NULL, tmp_item = {0};
-	int totitem = 0;
-	const int data_type = RNA_enum_get(ptr, "data_type");
-
 	if (!C) {  /* needed for docs and i18n tools */
 		return rna_enum_dt_layers_select_src_items;
 	}
 
+	EnumPropertyItem *item = NULL, tmp_item = {0};
+	int totitem = 0;
+	const int data_type = RNA_enum_get(ptr, "data_type");
+
 	Depsgraph *depsgraph = CTX_data_depsgraph(C);
 
-	RNA_enum_items_add_value(&item, &totitem, rna_enum_dt_layers_select_src_items, DT_LAYERS_ACTIVE_SRC);
+	PropertyRNA *prop = RNA_struct_find_property(ptr, "use_reverse_transfer");
+	const bool reverse_transfer = prop != NULL &&  RNA_property_boolean_get(ptr, prop);
+	const int layers_select_dst = reverse_transfer ? RNA_enum_get(ptr, "layers_select_src") :
+	                                                 RNA_enum_get(ptr, "layers_select_dst");
+
+	if (!reverse_transfer || layers_select_dst == DT_LAYERS_ACTIVE_DST || layers_select_dst >= 0) {
+		RNA_enum_items_add_value(&item, &totitem, rna_enum_dt_layers_select_src_items, DT_LAYERS_ACTIVE_SRC);
+	}
 	RNA_enum_items_add_value(&item, &totitem, rna_enum_dt_layers_select_src_items, DT_LAYERS_ALL_SRC);
 
+
+
 	if (data_type == DT_TYPE_MDEFORMVERT) {
 		Object *ob_src = CTX_data_active_object(C);
 
@@ -184,16 +193,19 @@ static const EnumPropertyItem *dt_layers_select_src_itemf(
 static const EnumPropertyItem *dt_layers_select_dst_itemf(
         bContext *C, PointerRNA *ptr, PropertyRNA *UNUSED(prop), bool *r_free)
 {
-	EnumPropertyItem *item = NULL;
-	int totitem = 0;
-
-	const int layers_select_src = RNA_enum_get(ptr, "layers_select_src");
-
 	if (!C) {  /* needed for docs and i18n tools */
 		return rna_enum_dt_layers_select_dst_items;
 	}
 
-	if (layers_select_src == DT_LAYERS_ACTIVE_SRC || layers_select_src >= 0) {
+	EnumPropertyItem *item = NULL;
+	int totitem = 0;
+
+	PropertyRNA *prop = RNA_struct_find_property(ptr, "use_reverse_transfer");
+	const bool reverse_transfer = prop != NULL &&  RNA_property_boolean_get(ptr, prop);
+	const int layers_select_src = reverse_transfer ? RNA_enum_get(ptr, "layers_select_dst") :
+	                                                 RNA_enum_get(ptr, "layers_select_src");
+
+	if (reverse_transfer || layers_select_src == DT_LAYERS_ACTIVE_SRC || layers_select_src >= 0) {
 		RNA_enum_items_add_value(&item, &totitem, rna_enum_dt_layers_select_dst_items, DT_LAYERS_ACTIVE_DST);
 	}
 	RNA_enum_items_add_value(&item, &totitem, rna_enum_dt_layers_select_dst_items, DT_LAYERS_NAME_DST);