Nodes: Sortable Multi Input Sockets

This Patch removes the auto sorting from Multi-Input Sockets and allows
the links to be sorted by drag and drop instead.
As a minor related change, it fixes the drawing of the mute line to
connect to the first input instead of the socket's center.

1 files changed, 77 insertions, 5 deletions

diff --git a/source/blender/editors/space_node/node_relationships.c b/source/blender/editors/space_node/node_relationships.c
index 35dd865047e..963349f876b 100644
--- a/source/blender/editors/space_node/node_relationships.c
+++ b/source/blender/editors/space_node/node_relationships.c
@@ -434,6 +434,75 @@ static bool snode_autoconnect_input(SpaceNode *snode,
   return true;
 }
 
+typedef struct LinkAndPosition {
+  struct bNodeLink *link;
+  float multi_socket_position[2];
+} LinkAndPosition;
+
+static int compare_link_by_y_position(const void *a, const void *b)
+{
+  const LinkAndPosition *link_and_position_a = *(const LinkAndPosition **)a;
+  const LinkAndPosition *link_and_position_b = *(const LinkAndPosition **)b;
+
+  BLI_assert(link_and_position_a->link->tosock == link_and_position_b->link->tosock);
+  const float link_a_y = link_and_position_a->multi_socket_position[1];
+  const float link_b_y = link_and_position_b->multi_socket_position[1];
+  return link_a_y > link_b_y ? 1 : -1;
+}
+
+void sort_multi_input_socket_links(SpaceNode *snode,
+                                   bNode *node,
+                                   bNodeLink *drag_link,
+                                   float cursor[2])
+{
+  LISTBASE_FOREACH (bNodeSocket *, socket, &node->inputs) {
+    if (!(socket->flag & SOCK_MULTI_INPUT)) {
+      continue;
+    }
+    /* The total is calculated in #node_update_nodetree, which runs before this draw step. */
+    int total_inputs = socket->total_inputs + 1;
+    struct LinkAndPosition **input_links = MEM_malloc_arrayN(
+        total_inputs, sizeof(LinkAndPosition *), __func__);
+
+    int index = 0;
+    LISTBASE_FOREACH (bNodeLink *, link, &snode->edittree->links) {
+      if (link->tosock == socket) {
+        struct LinkAndPosition *link_and_position = MEM_callocN(sizeof(struct LinkAndPosition),
+                                                                __func__);
+        link_and_position->link = link;
+        node_link_calculate_multi_input_position(link->tosock->locx,
+                                                 link->tosock->locy,
+                                                 link->multi_input_socket_index,
+                                                 link->tosock->total_inputs,
+                                                 link_and_position->multi_socket_position);
+        input_links[index] = link_and_position;
+        index++;
+      }
+    }
+
+    if (drag_link) {
+      LinkAndPosition *link_and_position = MEM_callocN(sizeof(LinkAndPosition), __func__);
+      link_and_position->link = drag_link;
+      copy_v2_v2(link_and_position->multi_socket_position, cursor);
+      input_links[index] = link_and_position;
+      index++;
+    }
+
+    qsort(input_links, index, sizeof(bNodeLink *), compare_link_by_y_position);
+
+    for (int i = 0; i < index; i++) {
+      input_links[i]->link->multi_input_socket_index = i;
+    }
+
+    for (int i = 0; i < index; i++) {
+      if (input_links[i]) {
+        MEM_freeN(input_links[i]);
+      }
+    }
+    MEM_freeN(input_links);
+  }
+}
+
 static void snode_autoconnect(Main *bmain,
                               SpaceNode *snode,
                               const bool allow_multiple,
@@ -816,10 +885,6 @@ static void node_link_find_socket(bContext *C, wmOperator *op, float cursor[2])
       LISTBASE_FOREACH (LinkData *, linkdata, &nldrag->links) {
         bNodeLink *link = linkdata->data;
 
-        /* skip if this is already the target socket */
-        if (link->tosock == tsock) {
-          continue;
-        }
         /* skip if socket is on the same node as the fromsock */
         if (tnode && link->fromnode == tnode) {
           continue;
@@ -828,12 +893,17 @@ static void node_link_find_socket(bContext *C, wmOperator *op, float cursor[2])
         /* attach links to the socket */
         link->tonode = tnode;
         link->tosock = tsock;
+        snode->runtime->last_node_hovered_while_dragging_a_link = tnode;
+        sort_multi_input_socket_links(snode, tnode, link, cursor);
       }
     }
     else {
       LISTBASE_FOREACH (LinkData *, linkdata, &nldrag->links) {
         bNodeLink *link = linkdata->data;
-
+        if (snode->runtime->last_node_hovered_while_dragging_a_link) {
+          sort_multi_input_socket_links(
+              snode, snode->runtime->last_node_hovered_while_dragging_a_link, NULL, cursor);
+        }
         link->tonode = NULL;
         link->tosock = NULL;
       }
@@ -2090,6 +2160,8 @@ void ED_node_link_insert(Main *bmain, ScrArea *area)
       snode_update(snode, select);
       ED_node_tag_update_id((ID *)snode->edittree);
       ED_node_tag_update_id(snode->id);
+
+      sort_multi_input_socket_links(snode, node, NULL, NULL);
     }
   }
 }