Fix T87356 & T87358: Small multi-input socket issues

T87356 occured because last_node_hovered_while_dragging_a_link was not
set on node_link_init.
The assert in T87358 failed because the sorting operation was called even
if the drag link contained a link to another socket.
A little one frame jump was caused because frame was refreshed after
picking a link and before sorting happened.

Reviewer: Hans Goudey

Differential Revision: https://developer.blender.org/D10940

2 files changed, 13 insertions, 2 deletions

diff --git a/source/blender/editors/space_node/node_intern.h b/source/blender/editors/space_node/node_intern.h
index 6f281ee05cc..c350e50b524 100644
--- a/source/blender/editors/space_node/node_intern.h
+++ b/source/blender/editors/space_node/node_intern.h
@@ -58,9 +58,11 @@ typedef struct bNodeLinkDrag {
   bool from_multi_input_socket;
   int in_out;
 
-  /** Temporarily stores the last picked link from multi input socket operator. */
+  /** Temporarily stores the last picked link from multi-input socket operator. */
   struct bNodeLink *last_picked_multi_input_socket_link;
 
+  /** Temporarily stores the last hovered socket for multi-input socket operator.
+   *  Store it to recalculate sorting after it is no longer hovered. */
   struct bNode *last_node_hovered_while_dragging_a_link;
 } bNodeLinkDrag;
 
diff --git a/source/blender/editors/space_node/node_relationships.c b/source/blender/editors/space_node/node_relationships.c
index 80601747f2e..4fa0c8c3c5a 100644
--- a/source/blender/editors/space_node/node_relationships.c
+++ b/source/blender/editors/space_node/node_relationships.c
@@ -224,6 +224,12 @@ static void pick_link(const bContext *C,
 
   BLI_addtail(&nldrag->links, linkdata);
   nodeRemLink(snode->edittree, link_to_pick);
+
+  BLI_assert(nldrag->last_node_hovered_while_dragging_a_link != NULL);
+
+  sort_multi_input_socket_links(
+      snode, nldrag->last_node_hovered_while_dragging_a_link, NULL,NULL);
+
   /* Send changed event to original link->tonode. */
   if (node) {
     snode_update(snode, node);
@@ -895,7 +901,9 @@ static void node_link_find_socket(bContext *C, wmOperator *op, float cursor[2])
               existing_link_connected_to_fromsock->multi_input_socket_index;
           continue;
         }
-        sort_multi_input_socket_links(snode, tnode, link, cursor);
+        if(link->tosock && link->tosock->flag & SOCK_MULTI_INPUT){
+          sort_multi_input_socket_links(snode, tnode, link, cursor);
+        }
       }
     }
     else {
@@ -1038,6 +1046,7 @@ static bNodeLinkDrag *node_link_init(Main *bmain, SpaceNode *snode, float cursor
   /* or an input? */
   else if (node_find_indicated_socket(snode, &node, &sock, cursor, SOCK_IN)) {
     nldrag = MEM_callocN(sizeof(bNodeLinkDrag), "drag link op customdata");
+    nldrag->last_node_hovered_while_dragging_a_link = node;
 
     const int num_links = nodeCountSocketLinks(snode->edittree, sock);
     if (num_links > 0) {