scripts/startup/bl_ui/space_node.py

@@ -862,6 +862,7 @@ class NODE_PT_overlay(Panel):
 
         col = layout.column()
         col.prop(overlay, "show_wire_color", text="Wire Colors")
+        col.prop(overlay, "show_reroute_auto_labels", text="Reroute Auto Labels")
 
         col.separator()
 

source/blender/blenkernel/BKE_blender_version.h

@@ -29,7 +29,7 @@ extern "C" {
 
 /* Blender file format version. */
 #define BLENDER_FILE_VERSION BLENDER_VERSION
-#define BLENDER_FILE_SUBVERSION 33
+#define BLENDER_FILE_SUBVERSION 34
 
 /* Minimum Blender version that supports reading file written with the current
  * version. Older Blender versions will test this and cancel loading the file, showing a warning to

source/blender/blenkernel/BKE_node.hh

@@ -1679,6 +1679,8 @@ void node_type_size_preset(bNodeType *ntype, eNodeSizePreset size);
 /** \name Node Generic Functions
  * \{ */
 
+void ntree_update_auto_labels(bNodeTree &ntree);
+
 bool node_is_connected_to_output(const bNodeTree *ntree, const bNode *node);
 
 bNodeSocket *node_find_enabled_socket(bNode &node, eNodeSocketInOut in_out, StringRef name);

source/blender/blenloader/intern/versioning_400.cc

@@ -3479,6 +3479,19 @@ void blo_do_versions_400(FileData *fd, Library * /*lib*/, Main *bmain)
     }
   }
 
+  if (!MAIN_VERSION_FILE_ATLEAST(bmain, 402, 34)) {
+    LISTBASE_FOREACH (bScreen *, screen, &bmain->screens) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
+          if (sl->spacetype == SPACE_NODE) {
+            SpaceNode *snode = (SpaceNode *)sl;
+            snode->overlay.flag |= SN_OVERLAY_SHOW_REROUTE_AUTO_LABELS;
+          }
+        }
+      }
+    }
+  }
+
   /**
    * Always bump subversion in BKE_blender_version.h when adding versioning
    * code here, and wrap it inside a MAIN_VERSION_FILE_ATLEAST check.

source/blender/editors/space_node/node_draw.cc

@@ -2046,6 +2046,15 @@ void node_socket_draw(bNodeSocket *sock, const rcti *rect, const float color[4],
   GPU_blend(state);
 }
 
+/* Some elements of the node UI are hidden, when they get too small. */
+#define NODE_TREE_SCALE_SMALL 0.2f
+
+/* The node tree scales both with the view and with the UI. */
+static float node_tree_view_scale(const SpaceNode &snode)
+{
+  return (1.0f / snode.runtime->aspect) * UI_SCALE_FAC;
+}
+
 static void node_draw_preview_background(rctf *rect)
 {
   GPUVertFormat *format = immVertexFormat();
@@ -3568,11 +3577,8 @@ static void node_draw_basis(const bContext &C,
     UI_draw_roundbox_4fv(&rect, false, BASIS_RAD + outline_width, color_outline);
   }
 
-  float scale;
-  UI_view2d_scale_get(&v2d, &scale, nullptr);
-
   /* Skip slow socket drawing if zoom is small. */
-  if (scale > 0.2f) {
+  if (node_tree_view_scale(snode) > NODE_TREE_SCALE_SMALL) {
     node_draw_sockets(v2d, C, ntree, node, block, true, false);
   }
 
@@ -4094,8 +4100,45 @@ static void frame_node_draw(const bContext &C,
   UI_block_draw(&C, &block);
 }
 
-static void reroute_node_draw(
-    const bContext &C, ARegion &region, bNodeTree &ntree, const bNode &node, uiBlock &block)
+static void reroute_node_draw_label(const SpaceNode &snode, const bNode &node, uiBlock &block)
+{
+  const bool has_label = node.label[0] != '\0';
+  const bool use_auto_label = !has_label && (snode.overlay.flag & SN_OVERLAY_SHOW_OVERLAYS) &&
+                              (snode.overlay.flag & SN_OVERLAY_SHOW_REROUTE_AUTO_LABELS);
+
+  if (!has_label && !use_auto_label) {
+    return;
+  }
+
+  /* Don't show the automatic label, when being zoomed out. */
+  if (!has_label && node_tree_view_scale(snode) < NODE_TREE_SCALE_SMALL) {
+    return;
+  }
+
+  const bNodeSocket *output = static_cast<bNodeSocket *>(node.outputs.first);
+  char showname[128]; /* 128 used below */
+  STRNCPY(showname, use_auto_label ? output->label : node.label);
+
+  const short width = 512;
+  const int x = BLI_rctf_cent_x(&node.runtime->totr) - (width / 2);
+  const int y = node.runtime->totr.ymax;
+
+  uiBut *label_but = uiDefBut(
+      &block, UI_BTYPE_LABEL, 0, showname, x, y, width, short(NODE_DY), nullptr, 0, 0, nullptr);
+
+  UI_but_drawflag_disable(label_but, UI_BUT_TEXT_LEFT);
+
+  if (use_auto_label && !(node.flag & NODE_SELECT)) {
+    UI_but_flag_enable(label_but, UI_BUT_INACTIVE);
+  }
+}
+
+static void reroute_node_draw(const bContext &C,
+                              ARegion &region,
+                              const SpaceNode &snode,
+                              bNodeTree &ntree,
+                              const bNode &node,
+                              uiBlock &block)
 {
   /* Skip if out of view. */
   const rctf &rct = node.runtime->totr;
@@ -4106,19 +4149,7 @@ static void reroute_node_draw(
     return;
   }
 
-  if (node.label[0] != '\0') {
-    /* Draw title (node label). */
-    char showname[128]; /* 128 used below */
-    STRNCPY(showname, node.label);
-    const short width = 512;
-    const int x = BLI_rctf_cent_x(&node.runtime->totr) - (width / 2);
-    const int y = node.runtime->totr.ymax;
-
-    uiBut *label_but = uiDefBut(
-        &block, UI_BTYPE_LABEL, 0, showname, x, y, width, short(NODE_DY), nullptr, 0, 0, nullptr);
-
-    UI_but_drawflag_disable(label_but, UI_BUT_TEXT_LEFT);
-  }
+  reroute_node_draw_label(snode, node, block);
 
   /* Only draw input socket as they all are placed on the same position highlight
    * if node itself is selected, since we don't display the node body separately. */
@@ -4141,7 +4172,7 @@ static void node_draw(const bContext &C,
     frame_node_draw(C, tree_draw_ctx, region, snode, ntree, node, block);
   }
   else if (node.is_reroute()) {
-    reroute_node_draw(C, region, ntree, node, block);
+    reroute_node_draw(C, region, snode, ntree, node, block);
   }
   else {
     const View2D &v2d = region.v2d;

source/blender/makesdna/DNA_space_types.h

@@ -1555,6 +1555,7 @@ typedef enum eSpaceNodeOverlay_Flag {
   SN_OVERLAY_SHOW_PATH = (1 << 4),
   SN_OVERLAY_SHOW_NAMED_ATTRIBUTES = (1 << 5),
   SN_OVERLAY_SHOW_PREVIEWS = (1 << 6),
+  SN_OVERLAY_SHOW_REROUTE_AUTO_LABELS = (1 << 7),
 } eSpaceNodeOverlay_Flag;
 
 typedef enum eSpaceNodeOverlay_preview_shape {

source/blender/makesrna/intern/rna_nodetree.cc

@@ -2221,6 +2221,16 @@ void rna_Node_update_relations(Main *bmain, Scene *scene, PointerRNA *ptr)
   DEG_relations_tag_update(bmain);
 }
 
+static void rna_Node_update_node_labels(Main *bmain, Scene *scene, PointerRNA *ptr)
+{
+  bNodeTree &ntree = *reinterpret_cast<bNodeTree *>(ptr->owner_id);
+  const bNode &node = *static_cast<bNode *>(ptr->data);
+
+  if (node.is_reroute()) {
+    blender::bke::ntree_update_auto_labels(ntree);
+  }
+}
+
 static void rna_Node_socket_value_update(ID *id, bNode * /*node*/, bContext *C)
 {
   BKE_ntree_update_tag_all(reinterpret_cast<bNodeTree *>(id));
@@ -9955,7 +9965,7 @@ static void rna_def_node(BlenderRNA *brna)
   prop = RNA_def_property(srna, "label", PROP_STRING, PROP_NONE);
   RNA_def_property_string_sdna(prop, nullptr, "label");
   RNA_def_property_ui_text(prop, "Label", "Optional custom node label");
-  RNA_def_property_update(prop, NC_NODE | ND_DISPLAY, nullptr);
+  RNA_def_property_update(prop, NC_NODE | ND_DISPLAY, "rna_Node_update_node_labels");
 
   prop = RNA_def_property(srna, "inputs", PROP_COLLECTION, PROP_NONE);
   RNA_def_property_collection_sdna(prop, nullptr, "inputs", nullptr);

source/blender/makesrna/intern/rna_space.cc

@@ -7573,6 +7573,15 @@ static void rna_def_space_node_overlay(BlenderRNA *brna)
       prop, "Show Wire Colors", "Color node links based on their connected sockets");
   RNA_def_property_update(prop, NC_SPACE | ND_SPACE_NODE, nullptr);
 
+  prop = RNA_def_property(srna, "show_reroute_auto_labels", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(
+      prop, nullptr, "overlay.flag", SN_OVERLAY_SHOW_REROUTE_AUTO_LABELS);
+  RNA_def_property_boolean_default(prop, false);
+  RNA_def_property_ui_text(prop,
+                           "Show Reroute Auto Labels",
+                           "Label reroute nodes based on the label of connected reroute nodes");
+  RNA_def_property_update(prop, NC_SPACE | ND_SPACE_NODE, nullptr);
+
   prop = RNA_def_property(srna, "show_timing", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, nullptr, "overlay.flag", SN_OVERLAY_SHOW_TIMINGS);
   RNA_def_property_boolean_default(prop, false);

source/blender/nodes/intern/node_common.cc

@@ -585,6 +585,52 @@ void register_node_type_reroute()
   nodeRegisterType(ntype);
 }
 
+/* NOTE: This uses the label of the reroute node's output socket to
+ * propagate the label from connected reroute nodes. */
+static void update_reroute_node_auto_labels(bNodeTree *ntree)
+{
+  using namespace blender;
+  ntree->ensure_topology_cache();
+
+  /* Clear auto-label. */
+  LISTBASE_FOREACH (bNode *, reroute, &ntree->nodes) {
+    if (!reroute->is_reroute()) {
+      continue;
+    }
+    bNodeSocket *output = reroute->output_sockets().first();
+    node_sock_label_clear(output);
+  }
+
+  for (bNode *reroute : ntree->toposort_left_to_right()) {
+    if (!reroute->is_reroute()) {
+      continue;
+    }
+
+    bNodeSocket *output = reroute->output_sockets().first();
+    const bNodeSocket &input = *reroute->input_sockets().first();
+    const Span<const bNodeSocket *> linked_sockets = input.directly_linked_sockets();
+
+    if (linked_sockets.is_empty()) {
+      continue;
+    }
+
+    const bNodeSocket &from_sock = *linked_sockets.first();
+    const bNode &from_node = from_sock.owner_node();
+
+    if (!from_node.is_reroute()) {
+      continue;
+    }
+
+    if (from_node.label[0] != '\0') {
+      /* Use the connected reroute's label to also label this reroute. */
+      node_sock_label(output, from_node.label);
+      continue;
+    }
+
+    node_sock_label(output, from_sock.label);
+  }
+}
+
 static void propagate_reroute_type_from_start_socket(
     bNodeSocket *start_socket,
     const MultiValueMap<bNodeSocket *, bNodeLink *> &links_map,
@@ -618,7 +664,7 @@ static void propagate_reroute_type_from_start_socket(
   }
 }
 
-void ntree_update_reroute_nodes(bNodeTree *ntree)
+void update_reroute_node_socket_types(bNodeTree *ntree)
 {
   /* Contains nodes that are linked to at least one reroute node. */
   Set<bNode *> nodes_linked_with_reroutes;
@@ -676,6 +722,17 @@ void ntree_update_reroute_nodes(bNodeTree *ntree)
   }
 }
 
+void ntree_update_reroute_nodes(bNodeTree *ntree)
+{
+  update_reroute_node_socket_types(ntree);
+  update_reroute_node_auto_labels(ntree);
+}
+
+void blender::bke::ntree_update_auto_labels(bNodeTree &ntree)
+{
+  update_reroute_node_auto_labels(&ntree);
+}
+
 bool blender::bke::node_is_connected_to_output(const bNodeTree *ntree, const bNode *node)
 {
   ntree->ensure_topology_cache();