Nodes: Add support to mute node wires

This patch adds the ability to mute individual wires in the node editor.
This is invoked like the cut links operator but with a new shortcut.

Mute = Ctrl + Alt
Cut = Ctrl

Dragging over wires will toggle the mute state for that wire.
The muted wires are drawn in red with a bar across the center.
Red is used in the nodes context to indicate invalid links, muted links and internal links.

When a wire is muted it exposes the original node buttons which are normally hidden when a wire is connected.

Downstream and upstream links connected using reroute nodes are also muted.

Outside scope of patch:
- Add support for pynodes e.g. Animation Nodes
- Requires minor change to check for muted links using the `is_muted` link property or the `is_linked` socket property.

Maniphest Tasks: T52659

Differential Revision: https://developer.blender.org/D2807

1 files changed, 2 insertions, 1 deletions

diff --git a/intern/cycles/blender/blender_shader.cpp b/intern/cycles/blender/blender_shader.cpp
index a1ab5277744..72328333732 100644
--- a/intern/cycles/blender/blender_shader.cpp
+++ b/intern/cycles/blender/blender_shader.cpp
@@ -1234,7 +1234,8 @@ static void add_nodes(Scene *scene,
   for (BL::NodeLink &b_link : b_ntree.links) {
     /* Ignore invalid links to avoid unwanted cycles created in graph.
      * Also ignore links with unavailable sockets. */
-    if (!(b_link.is_valid() && b_link.from_socket().enabled() && b_link.to_socket().enabled())) {
+    if (!(b_link.is_valid() && b_link.from_socket().enabled() && b_link.to_socket().enabled()) ||
+        b_link.is_muted()) {
       continue;
     }
     /* get blender link data */