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, 1 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_node_types.h b/source/blender/makesdna/DNA_node_types.h
index 06ee22b1452..acbe9da45fd 100644
--- a/source/blender/makesdna/DNA_node_types.h
+++ b/source/blender/makesdna/DNA_node_types.h
@@ -402,6 +402,7 @@ typedef struct bNodeLink {
 #define NODE_LINK_VALID (1 << 1)
 #define NODE_LINK_TEST (1 << 2)           /* free test flag, undefined */
 #define NODE_LINK_TEMP_HIGHLIGHT (1 << 3) /* Link is highlighted for picking. */
+#define NODE_LINK_MUTED (1 << 4)           /* Link is muted. */
 
 /* tree->edit_quality/tree->render_quality */
 #define NTREE_QUALITY_HIGH 0