From aa83fb0337d279182f1eba223c967276a39e04bf Mon Sep 17 00:00:00 2001
From: Daybreak <daybreak-2@noreply.localhost>
Date: Tue, 29 Aug 2023 15:51:18 +0200
Subject: [PATCH] Geometry Nodes: Support drag & drop for Materials

Allows for materials to be dragged and dropped into the
geometry nodes editor, similar to collections or objects.

Pull Request: https://projects.blender.org/blender/blender/pulls/111368
---
 source/blender/editors/space_node/node_add.cc | 76 +++++++++++++++++++
 .../blender/editors/space_node/node_intern.hh |  1 +
 source/blender/editors/space_node/node_ops.cc |  1 +
 .../blender/editors/space_node/space_node.cc  | 11 +++
 4 files changed, 89 insertions(+)

diff --git a/source/blender/editors/space_node/node_add.cc b/source/blender/editors/space_node/node_add.cc
index 019b7368f5e..5a026d8a237 100644
--- a/source/blender/editors/space_node/node_add.cc
+++ b/source/blender/editors/space_node/node_add.cc
@@ -843,6 +843,82 @@ void NODE_OT_add_mask(wmOperatorType *ot)
 
 /** \} */
 
+/* -------------------------------------------------------------------- */
+/** \name Add Material Operator
+ * \{ */
+
+static int node_add_material_exec(bContext *C, wmOperator *op)
+{
+  Main *bmain = CTX_data_main(C);
+  SpaceNode *snode = CTX_wm_space_node(C);
+  bNodeTree *ntree = snode->edittree;
+
+  Material *material = reinterpret_cast<Material *>(
+      WM_operator_properties_id_lookup_from_name_or_session_uuid(bmain, op->ptr, ID_MA));
+
+  if (!material) {
+    return OPERATOR_CANCELLED;
+  }
+
+  ED_preview_kill_jobs(CTX_wm_manager(C), CTX_data_main(C));
+
+  bNode *material_node = add_static_node(*C, GEO_NODE_INPUT_MATERIAL, snode->runtime->cursor);
+  if (!material_node) {
+    BKE_report(op->reports, RPT_WARNING, "Could not add material");
+    return OPERATOR_CANCELLED;
+  }
+
+  material_node->id = &material->id;
+  id_us_plus(&material->id);
+
+  ED_node_tree_propagate_change(C, bmain, ntree);
+  DEG_relations_tag_update(bmain);
+
+  return OPERATOR_FINISHED;
+}
+
+static int node_add_material_invoke(bContext *C, wmOperator *op, const wmEvent *event)
+{
+  ARegion *region = CTX_wm_region(C);
+  SpaceNode *snode = CTX_wm_space_node(C);
+
+  /* Convert mouse coordinates to v2d space. */
+  UI_view2d_region_to_view(&region->v2d,
+                           event->mval[0],
+                           event->mval[1],
+                           &snode->runtime->cursor[0],
+                           &snode->runtime->cursor[1]);
+
+  snode->runtime->cursor[0] /= UI_SCALE_FAC;
+  snode->runtime->cursor[1] /= UI_SCALE_FAC;
+
+  return node_add_material_exec(C, op);
+}
+
+static bool node_add_material_poll(bContext *C)
+{
+  const SpaceNode *snode = CTX_wm_space_node(C);
+  return ED_operator_node_editable(C) && ELEM(snode->nodetree->type, NTREE_GEOMETRY);
+}
+
+void NODE_OT_add_material(wmOperatorType *ot)
+{
+  /* identifiers */
+  ot->name = "Add Material";
+  ot->description = "Add a material node to the current node editor";
+  ot->idname = "NODE_OT_add_material";
+
+  /* callbacks */
+  ot->exec = node_add_material_exec;
+  ot->invoke = node_add_material_invoke;
+  ot->poll = node_add_material_poll;
+
+  /* flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_INTERNAL;
+
+  WM_operator_properties_id_lookup(ot, true);
+}
+
 /* -------------------------------------------------------------------- */
 /** \name New Node Tree Operator
  * \{ */
diff --git a/source/blender/editors/space_node/node_intern.hh b/source/blender/editors/space_node/node_intern.hh
index cf23d1b6f8e..525ec67f54d 100644
--- a/source/blender/editors/space_node/node_intern.hh
+++ b/source/blender/editors/space_node/node_intern.hh
@@ -290,6 +290,7 @@ void NODE_OT_add_object(wmOperatorType *ot);
 void NODE_OT_add_collection(wmOperatorType *ot);
 void NODE_OT_add_file(wmOperatorType *ot);
 void NODE_OT_add_mask(wmOperatorType *ot);
+void NODE_OT_add_material(wmOperatorType *ot);
 void NODE_OT_new_node_tree(wmOperatorType *ot);
 
 /* `node_group.cc` */
diff --git a/source/blender/editors/space_node/node_ops.cc b/source/blender/editors/space_node/node_ops.cc
index caabbb40d96..d468bd7a4ac 100644
--- a/source/blender/editors/space_node/node_ops.cc
+++ b/source/blender/editors/space_node/node_ops.cc
@@ -84,6 +84,7 @@ void node_operatortypes()
   WM_operatortype_append(NODE_OT_add_collection);
   WM_operatortype_append(NODE_OT_add_file);
   WM_operatortype_append(NODE_OT_add_mask);
+  WM_operatortype_append(NODE_OT_add_material);
 
   WM_operatortype_append(NODE_OT_new_node_tree);
 
diff --git a/source/blender/editors/space_node/space_node.cc b/source/blender/editors/space_node/space_node.cc
index 848b2bbdce9..8ac65616dd6 100644
--- a/source/blender/editors/space_node/space_node.cc
+++ b/source/blender/editors/space_node/space_node.cc
@@ -702,6 +702,11 @@ static bool node_mask_drop_poll(bContext * /*C*/, wmDrag *drag, const wmEvent *
   return WM_drag_is_ID_type(drag, ID_MSK);
 }
 
+static bool node_material_drop_poll(bContext *C, wmDrag *drag, const wmEvent * /*event*/)
+{
+  return WM_drag_is_ID_type(drag, ID_MA) && !UI_but_active_drop_name(C);
+}
+
 static void node_group_drop_copy(bContext *C, wmDrag *drag, wmDropBox *drop)
 {
   ID *id = WM_drag_get_local_ID_or_import_from_asset(C, drag, 0);
@@ -771,6 +776,12 @@ static void node_dropboxes()
                  node_id_drop_copy,
                  WM_drag_free_imported_drag_ID,
                  nullptr);
+  WM_dropbox_add(lb,
+                 "NODE_OT_add_material",
+                 node_material_drop_poll,
+                 node_id_drop_copy,
+                 WM_drag_free_imported_drag_ID,
+                 nullptr);
 }
 
 /* ************* end drop *********** */