Geometry Nodes: Clarify modifier node group errors

This commit adds modifier error messages to some of the cases
where the node group is configured improperly. It also clears the
geometry set when there is an error with the node group. This is
consistent to what we do in nodes themselves, and feels more
intuitive than passing the input geometry through the node group
silently.

Fixes T87142

1 files changed, 7 insertions, 11 deletions

diff --git a/source/blender/modifiers/intern/MOD_nodes.cc b/source/blender/modifiers/intern/MOD_nodes.cc
index 6ea47881982..7740fe891e3 100644
--- a/source/blender/modifiers/intern/MOD_nodes.cc
+++ b/source/blender/modifiers/intern/MOD_nodes.cc
@@ -1049,17 +1049,6 @@ static void check_property_socket_sync(const Object *ob, ModifierData *md)
       continue;
     }
   }
-
-  bool has_geometry_output = false;
-  LISTBASE_FOREACH (const bNodeSocket *, socket, &nmd->node_group->outputs) {
-    if (socket->type == SOCK_GEOMETRY) {
-      has_geometry_output = true;
-    }
-  }
-
-  if (!has_geometry_output) {
-    BKE_modifier_set_error(ob, md, "Node group must have a geometry output");
-  }
 }
 
 static void modifyGeometry(ModifierData *md,
@@ -1078,6 +1067,7 @@ static void modifyGeometry(ModifierData *md,
 
   if (tree.has_link_cycles()) {
     BKE_modifier_set_error(ctx->object, md, "Node group has cycles");
+    geometry_set.clear();
     return;
   }
 
@@ -1085,17 +1075,23 @@ static void modifyGeometry(ModifierData *md,
   Span<const NodeRef *> input_nodes = root_tree_ref.nodes_by_type("NodeGroupInput");
   Span<const NodeRef *> output_nodes = root_tree_ref.nodes_by_type("NodeGroupOutput");
   if (output_nodes.size() != 1) {
+    BKE_modifier_set_error(ctx->object, md, "Node group must have a single output node");
+    geometry_set.clear();
     return;
   }
 
   const NodeRef &output_node = *output_nodes[0];
   Span<const InputSocketRef *> group_outputs = output_node.inputs().drop_back(1);
   if (group_outputs.is_empty()) {
+    BKE_modifier_set_error(ctx->object, md, "Node group must have an output socket");
+    geometry_set.clear();
     return;
   }
 
   const InputSocketRef *first_output_socket = group_outputs[0];
   if (first_output_socket->idname() != "NodeSocketGeometry") {
+    BKE_modifier_set_error(ctx->object, md, "Node group's first output must be a geometry");
+    geometry_set.clear();
     return;
   }