[AnimationNodeBlendTreeEditor] Usability improvements

- Add possibility to exclude multiple (selected) nodes.
- Add context menu (Right click) to add nodes.

(cherry picked from commit ccbf57611b85a5295b37a3fed6b602ef23f96b7a)

editor/plugins/animation_blend_tree_editor_plugin.cpp

@@ -80,6 +80,7 @@ void AnimationNodeBlendTreeEditor::_update_options_menu() {
 	}
 	add_node->get_popup()->add_separator();
 	add_node->get_popup()->add_item(TTR("Load..."), MENU_LOAD_FILE);
+	use_popup_menu_position = false;
 }
 
 Size2 AnimationNodeBlendTreeEditor::get_minimum_size() const {
@@ -317,7 +318,15 @@ void AnimationNodeBlendTreeEditor::_add_node(int p_idx) {
 		EditorNode::get_singleton()->show_warning(TTR("Output node can't be added to the blend tree."));
 		return;
 	}
-	Point2 instance_pos = graph->get_scroll_ofs() + graph->get_size() * 0.5;
+
+	Point2 instance_pos = graph->get_scroll_ofs();
+	if (use_popup_menu_position) {
+		instance_pos += popup_menu_position;
+	} else {
+		instance_pos += graph->get_size() * 0.5;
+	}
+
+	instance_pos /= graph->get_zoom();
 
 	int base = 1;
 	String name = base_name;
@@ -412,6 +421,40 @@ void AnimationNodeBlendTreeEditor::_delete_request(const String &p_which) {
 	undo_redo->commit_action();
 }
 
+void AnimationNodeBlendTreeEditor::_delete_nodes_request() {
+
+	List<StringName> to_erase;
+
+	for (int i = 0; i < graph->get_child_count(); i++) {
+		GraphNode *gn = Object::cast_to<GraphNode>(graph->get_child(i));
+		if (gn) {
+			if (gn->is_selected() && gn->is_close_button_visible()) {
+				to_erase.push_back(gn->get_name());
+			}
+		}
+	}
+
+	if (to_erase.empty())
+		return;
+
+	undo_redo->create_action(TTR("Delete Node(s)"));
+
+	for (List<StringName>::Element *F = to_erase.front(); F; F = F->next()) {
+		_delete_request(F->get());
+	}
+
+	undo_redo->commit_action();
+}
+
+void AnimationNodeBlendTreeEditor::_popup_request(const Vector2 &p_position) {
+
+	_update_options_menu();
+	use_popup_menu_position = true;
+	popup_menu_position = graph->get_local_mouse_position();
+	add_node->get_popup()->set_position(p_position);
+	add_node->get_popup()->popup();
+}
+
 void AnimationNodeBlendTreeEditor::_node_selected(Object *p_node) {
 
 	GraphNode *gn = Object::cast_to<GraphNode>(p_node);
@@ -730,6 +773,8 @@ void AnimationNodeBlendTreeEditor::_bind_methods() {
 	ClassDB::bind_method("_open_in_editor", &AnimationNodeBlendTreeEditor::_open_in_editor);
 	ClassDB::bind_method("_scroll_changed", &AnimationNodeBlendTreeEditor::_scroll_changed);
 	ClassDB::bind_method("_delete_request", &AnimationNodeBlendTreeEditor::_delete_request);
+	ClassDB::bind_method("_delete_nodes_request", &AnimationNodeBlendTreeEditor::_delete_nodes_request);
+	ClassDB::bind_method("_popup_request", &AnimationNodeBlendTreeEditor::_popup_request);
 	ClassDB::bind_method("_edit_filters", &AnimationNodeBlendTreeEditor::_edit_filters);
 	ClassDB::bind_method("_update_filters", &AnimationNodeBlendTreeEditor::_update_filters);
 	ClassDB::bind_method("_filter_edited", &AnimationNodeBlendTreeEditor::_filter_edited);
@@ -850,6 +895,7 @@ AnimationNodeBlendTreeEditor::AnimationNodeBlendTreeEditor() {
 
 	singleton = this;
 	updating = false;
+	use_popup_menu_position = false;
 
 	graph = memnew(GraphEdit);
 	add_child(graph);
@@ -860,6 +906,8 @@ AnimationNodeBlendTreeEditor::AnimationNodeBlendTreeEditor() {
 	graph->connect("disconnection_request", this, "_disconnection_request", varray(), CONNECT_DEFERRED);
 	graph->connect("node_selected", this, "_node_selected");
 	graph->connect("scroll_offset_changed", this, "_scroll_changed");
+	graph->connect("delete_nodes_request", this, "_delete_nodes_request");
+	graph->connect("popup_request", this, "_popup_request");
 
 	VSeparator *vs = memnew(VSeparator);
 	graph->get_zoom_hbox()->add_child(vs);

editor/plugins/animation_blend_tree_editor_plugin.h

@@ -51,6 +51,8 @@ class AnimationNodeBlendTreeEditor : public AnimationTreeNodeEditorPlugin {
 	Ref<AnimationNodeBlendTree> blend_tree;
 	GraphEdit *graph;
 	MenuButton *add_node;
+	Vector2 popup_menu_position;
+	bool use_popup_menu_position;
 
 	PanelContainer *error_panel;
 	Label *error_label;
@@ -97,6 +99,8 @@ class AnimationNodeBlendTreeEditor : public AnimationTreeNodeEditorPlugin {
 	void _open_in_editor(const String &p_which);
 	void _anim_selected(int p_index, Array p_options, const String &p_node);
 	void _delete_request(const String &p_which);
+	void _delete_nodes_request();
+	void _popup_request(const Vector2 &p_position);
 
 	bool _update_filters(const Ref<AnimationNode> &anode);
 	void _edit_filters(const String &p_which);