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

4 files changed, 155 insertions, 11 deletions

diff --git a/source/blender/editors/space_node/drawnode.c b/source/blender/editors/space_node/drawnode.c
index 0f2b2b435bc..1354c06305c 100644
--- a/source/blender/editors/space_node/drawnode.c
+++ b/source/blender/editors/space_node/drawnode.c
@@ -3751,17 +3751,21 @@ bool node_link_bezier_points(const View2D *v2d,
 #define LINK_WIDTH (2.5f * UI_DPI_FAC)
 #define ARROW_SIZE (7 * UI_DPI_FAC)
 
+/* Reroute arrow shape and mute bar. These are expanded here and shrunk in the glsl code.
+ * See: gpu_shader_2D_nodelink_vert.glsl */
 static float arrow_verts[3][2] = {{-1.0f, 1.0f}, {0.0f, 0.0f}, {-1.0f, -1.0f}};
 static float arrow_expand_axis[3][2] = {{0.7071f, 0.7071f}, {M_SQRT2, 0.0f}, {0.7071f, -0.7071f}};
+static float mute_verts[3][2] = {{0.7071f, 1.0f}, {0.7071f, 0.0f}, {0.7071f, -1.0f}};
+static float mute_expand_axis[3][2] = {{1.0f, 0.0f}, {1.0f, 0.0f}, {1.0f, -0.0f}};
 
 static struct {
   GPUBatch *batch;        /* for batching line together */
   GPUBatch *batch_single; /* for single line */
   GPUVertBuf *inst_vbo;
   uint p0_id, p1_id, p2_id, p3_id;
-  uint colid_id;
+  uint colid_id, muted_id;
   GPUVertBufRaw p0_step, p1_step, p2_step, p3_step;
-  GPUVertBufRaw colid_step;
+  GPUVertBufRaw colid_step, muted_step;
   uint count;
   bool enabled;
 } g_batch_link = {0};
@@ -3774,6 +3778,8 @@ static void nodelink_batch_reset(void)
   GPU_vertbuf_attr_get_raw_data(g_batch_link.inst_vbo, g_batch_link.p3_id, &g_batch_link.p3_step);
   GPU_vertbuf_attr_get_raw_data(
       g_batch_link.inst_vbo, g_batch_link.colid_id, &g_batch_link.colid_step);
+  GPU_vertbuf_attr_get_raw_data(
+      g_batch_link.inst_vbo, g_batch_link.muted_id, &g_batch_link.muted_step);
   g_batch_link.count = 0;
 }
 
@@ -3801,6 +3807,8 @@ static void nodelink_batch_init(void)
   int vcount = LINK_RESOL * 2; /* curve */
   vcount += 2;                 /* restart strip */
   vcount += 3 * 2;             /* arrow */
+  vcount += 2;                 /* restart strip */
+  vcount += 3 * 2;             /* mute */
   vcount *= 2;                 /* shadow */
   vcount += 2;                 /* restart strip */
   GPU_vertbuf_data_alloc(vbo, vcount);
@@ -3844,6 +3852,25 @@ static void nodelink_batch_init(void)
     }
 
     /* restart */
+    set_nodelink_vertex(vbo, uv_id, pos_id, expand_id, v++, uv, pos, exp);
+
+    uv[0] = 127;
+    uv[1] = 0;
+    copy_v2_v2(pos, mute_verts[0]);
+    copy_v2_v2(exp, mute_expand_axis[0]);
+    set_nodelink_vertex(vbo, uv_id, pos_id, expand_id, v++, uv, pos, exp);
+    /* bar */
+    for (int i = 0; i < 3; ++i) {
+      uv[1] = 0;
+      copy_v2_v2(pos, mute_verts[i]);
+      copy_v2_v2(exp, mute_expand_axis[i]);
+      set_nodelink_vertex(vbo, uv_id, pos_id, expand_id, v++, uv, pos, exp);
+
+      uv[1] = 255;
+      set_nodelink_vertex(vbo, uv_id, pos_id, expand_id, v++, uv, pos, exp);
+    }
+
+    /* restart */
     if (k == 0) {
       set_nodelink_vertex(vbo, uv_id, pos_id, expand_id, v++, uv, pos, exp);
     }
@@ -3867,6 +3894,8 @@ static void nodelink_batch_init(void)
       &format_inst, "P3", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
   g_batch_link.colid_id = GPU_vertformat_attr_add(
       &format_inst, "colid_doarrow", GPU_COMP_U8, 4, GPU_FETCH_INT);
+  g_batch_link.muted_id = GPU_vertformat_attr_add(
+      &format_inst, "domuted", GPU_COMP_U8, 2, GPU_FETCH_INT);
   g_batch_link.inst_vbo = GPU_vertbuf_create_with_format_ex(&format_inst, GPU_USAGE_STREAM);
   /* Alloc max count but only draw the range we need. */
   GPU_vertbuf_data_alloc(g_batch_link.inst_vbo, NODELINK_GROUP_SIZE);
@@ -3941,12 +3970,13 @@ static void nodelink_batch_add_link(const SpaceNode *snode,
                                     int th_col1,
                                     int th_col2,
                                     int th_col3,
-                                    bool drawarrow)
+                                    bool drawarrow,
+                                    bool drawmuted)
 {
   /* Only allow these colors. If more is needed, you need to modify the shader accordingly. */
   BLI_assert(ELEM(th_col1, TH_WIRE_INNER, TH_WIRE, TH_ACTIVE, TH_EDGE_SELECT, TH_REDALERT));
   BLI_assert(ELEM(th_col2, TH_WIRE_INNER, TH_WIRE, TH_ACTIVE, TH_EDGE_SELECT, TH_REDALERT));
-  BLI_assert(ELEM(th_col3, TH_WIRE, -1));
+  BLI_assert(ELEM(th_col3, TH_WIRE, TH_REDALERT, -1));
 
   g_batch_link.count++;
   copy_v2_v2(GPU_vertbuf_raw_step(&g_batch_link.p0_step), p0);
@@ -3958,6 +3988,8 @@ static void nodelink_batch_add_link(const SpaceNode *snode,
   colid[1] = nodelink_get_color_id(th_col2);
   colid[2] = nodelink_get_color_id(th_col3);
   colid[3] = drawarrow;
+  char *muted = GPU_vertbuf_raw_step(&g_batch_link.muted_step);
+  muted[0] = drawmuted;
 
   if (g_batch_link.count == NODELINK_GROUP_SIZE) {
     nodelink_batch_draw(snode);
@@ -3977,7 +4009,7 @@ void node_draw_link_bezier(const View2D *v2d,
   if (node_link_bezier_handles(v2d, snode, link, vec)) {
     int drawarrow = ((link->tonode && (link->tonode->type == NODE_REROUTE)) &&
                      (link->fromnode && (link->fromnode->type == NODE_REROUTE)));
-
+    int drawmuted = (link->flag & NODE_LINK_MUTED);
     if (g_batch_link.batch == NULL) {
       nodelink_batch_init();
     }
@@ -3985,7 +4017,7 @@ void node_draw_link_bezier(const View2D *v2d,
     if (g_batch_link.enabled && !highlighted) {
       /* Add link to batch. */
       nodelink_batch_add_link(
-          snode, vec[0], vec[1], vec[2], vec[3], th_col1, th_col2, th_col3, drawarrow);
+          snode, vec[0], vec[1], vec[2], vec[3], th_col1, th_col2, th_col3, drawarrow, drawmuted);
     }
     else {
       /* Draw single link. */
@@ -4009,6 +4041,7 @@ void node_draw_link_bezier(const View2D *v2d,
       GPU_batch_uniform_1f(batch, "expandSize", snode->runtime->aspect * LINK_WIDTH);
       GPU_batch_uniform_1f(batch, "arrowSize", ARROW_SIZE);
       GPU_batch_uniform_1i(batch, "doArrow", drawarrow);
+      GPU_batch_uniform_1i(batch, "doMuted", drawmuted);
       GPU_batch_draw(batch);
     }
   }
@@ -4041,8 +4074,11 @@ void node_draw_link(View2D *v2d, SpaceNode *snode, bNodeLink *link)
       if (link->flag & NODE_LINKFLAG_HILITE) {
         th_col1 = th_col2 = TH_ACTIVE;
       }
+      else if (link->flag & NODE_LINK_MUTED) {
+        th_col1 = th_col2 = TH_REDALERT;
+      }
       else {
-        /* regular link */
+        /* Regular link, highlight if connected to selected node. */
         if (link->fromnode && link->fromnode->flag & SELECT) {
           th_col1 = TH_EDGE_SELECT;
         }
@@ -4052,7 +4088,8 @@ void node_draw_link(View2D *v2d, SpaceNode *snode, bNodeLink *link)
       }
     }
     else {
-      th_col1 = th_col2 = TH_REDALERT;
+      /* Invalid link. */
+      th_col1 = th_col2 = th_col3 = TH_REDALERT;
       // th_col3 = -1; /* no shadow */
     }
   }
diff --git a/source/blender/editors/space_node/node_intern.h b/source/blender/editors/space_node/node_intern.h
index 1840ec93f6f..21a36ff9683 100644
--- a/source/blender/editors/space_node/node_intern.h
+++ b/source/blender/editors/space_node/node_intern.h
@@ -234,6 +234,7 @@ void NODE_OT_link(struct wmOperatorType *ot);
 void NODE_OT_link_make(struct wmOperatorType *ot);
 void NODE_OT_links_cut(struct wmOperatorType *ot);
 void NODE_OT_links_detach(struct wmOperatorType *ot);
+void NODE_OT_links_mute(struct wmOperatorType *ot);
 
 void NODE_OT_parent_set(struct wmOperatorType *ot);
 void NODE_OT_join(struct wmOperatorType *ot);
diff --git a/source/blender/editors/space_node/node_ops.c b/source/blender/editors/space_node/node_ops.c
index ef28cfe8a8b..e35b444aa11 100644
--- a/source/blender/editors/space_node/node_ops.c
+++ b/source/blender/editors/space_node/node_ops.c
@@ -68,6 +68,7 @@ void node_operatortypes(void)
   WM_operatortype_append(NODE_OT_link_make);
   WM_operatortype_append(NODE_OT_links_cut);
   WM_operatortype_append(NODE_OT_links_detach);
+  WM_operatortype_append(NODE_OT_links_mute);
   WM_operatortype_append(NODE_OT_add_reroute);
 
   WM_operatortype_append(NODE_OT_group_make);
diff --git a/source/blender/editors/space_node/node_relationships.c b/source/blender/editors/space_node/node_relationships.c
index ee07ec7a55c..2cc44d72c72 100644
--- a/source/blender/editors/space_node/node_relationships.c
+++ b/source/blender/editors/space_node/node_relationships.c
@@ -1227,8 +1227,8 @@ void NODE_OT_link_make(wmOperatorType *ot)
       ot->srna, "replace", 0, "Replace", "Replace socket connections with the new links");
 }
 
-/* ********************** Cut Link operator ***************** */
-static bool cut_links_intersect(bNodeLink *link, const float mcoords[][2], int tot)
+/* ********************** Node Link Intersect ***************** */
+static bool node_links_intersect(bNodeLink *link, const float mcoords[][2], int tot)
 {
   float coord_array[NODE_LINK_RESOL + 1][2];
 
@@ -1244,6 +1244,7 @@ static bool cut_links_intersect(bNodeLink *link, const float mcoords[][2], int t
   return 0;
 }
 
+/* ********************** Cut Link operator ***************** */
 static int cut_links_exec(bContext *C, wmOperator *op)
 {
   Main *bmain = CTX_data_main(C);
@@ -1276,7 +1277,7 @@ static int cut_links_exec(bContext *C, wmOperator *op)
         continue;
       }
 
-      if (cut_links_intersect(link, mcoords, i)) {
+      if (node_links_intersect(link, mcoords, i)) {
 
         if (found == false) {
           /* TODO(sergey): Why did we kill jobs twice? */
@@ -1335,6 +1336,110 @@ void NODE_OT_links_cut(wmOperatorType *ot)
   RNA_def_int(ot->srna, "cursor", WM_CURSOR_KNIFE, 0, INT_MAX, "Cursor", "", 0, INT_MAX);
 }
 
+/* ********************** Mute links operator ***************** */
+
+static int mute_links_exec(bContext *C, wmOperator *op)
+{
+  Main *bmain = CTX_data_main(C);
+  SpaceNode *snode = CTX_wm_space_node(C);
+  ARegion *region = CTX_wm_region(C);
+  bool do_tag_update = false;
+
+  int i = 0;
+  float mcoords[256][2];
+  RNA_BEGIN (op->ptr, itemptr, "path") {
+    float loc[2];
+
+    RNA_float_get_array(&itemptr, "loc", loc);
+    UI_view2d_region_to_view(
+        &region->v2d, (int)loc[0], (int)loc[1], &mcoords[i][0], &mcoords[i][1]);
+    i++;
+    if (i >= 256) {
+      break;
+    }
+  }
+  RNA_END;
+
+  if (i > 1) {
+    ED_preview_kill_jobs(CTX_wm_manager(C), bmain);
+
+    /* Count intersected links and clear test flag. */
+    int tot = 0;
+    LISTBASE_FOREACH (bNodeLink *, link, &snode->edittree->links) {
+      if (nodeLinkIsHidden(link)) {
+        continue;
+      }
+      link->flag &= ~NODE_LINK_TEST;
+      if (node_links_intersect(link, mcoords, i)) {
+        tot++;
+      }
+    }
+    if (tot == 0) {
+      return OPERATOR_CANCELLED;
+    }
+
+    /* Mute links. */
+    LISTBASE_FOREACH (bNodeLink *, link, &snode->edittree->links) {
+      if (nodeLinkIsHidden(link) || (link->flag & NODE_LINK_TEST)) {
+        continue;
+      }
+
+      if (node_links_intersect(link, mcoords, i)) {
+        do_tag_update |= (do_tag_update ||
+                          node_connected_to_output(bmain, snode->edittree, link->tonode));
+
+        snode_update(snode, link->tonode);
+        nodeMuteLinkToggle(snode->edittree, link);
+      }
+    }
+
+    /* Clear remaining test flags. */
+    LISTBASE_FOREACH (bNodeLink *, link, &snode->edittree->links) {
+      if (nodeLinkIsHidden(link)) {
+        continue;
+      }
+      link->flag &= ~NODE_LINK_TEST;
+    }
+
+    do_tag_update |= ED_node_is_geometry(snode);
+
+    ntreeUpdateTree(CTX_data_main(C), snode->edittree);
+    snode_notify(C, snode);
+    if (do_tag_update) {
+      snode_dag_update(C, snode);
+    }
+
+    return OPERATOR_FINISHED;
+  }
+
+  return OPERATOR_CANCELLED | OPERATOR_PASS_THROUGH;
+}
+
+void NODE_OT_links_mute(wmOperatorType *ot)
+{
+  ot->name = "Mute Links";
+  ot->idname = "NODE_OT_links_mute";
+  ot->description = "Use the mouse to mute links";
+
+  ot->invoke = WM_gesture_lines_invoke;
+  ot->modal = WM_gesture_lines_modal;
+  ot->exec = mute_links_exec;
+  ot->cancel = WM_gesture_lines_cancel;
+
+  ot->poll = ED_operator_node_editable;
+
+  /* flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+
+  /* properties */
+  PropertyRNA *prop;
+  prop = RNA_def_collection_runtime(ot->srna, "path", &RNA_OperatorMousePath, "Path", "");
+  RNA_def_property_flag(prop, PROP_HIDDEN | PROP_SKIP_SAVE);
+
+  /* internal */
+  RNA_def_int(ot->srna, "cursor", WM_CURSOR_MUTE, 0, INT_MAX, "Cursor", "", 0, INT_MAX);
+}
+
 /* ********************** Detach links operator ***************** */
 
 static int detach_links_exec(bContext *C, wmOperator *UNUSED(op))