From 5d75edb3b593a74db02fce59a63b63e99edecdf7 Mon Sep 17 00:00:00 2001
From: Tomasz Chabora <kobewi4e@gmail.com>
Date: Sun, 8 Nov 2020 21:43:56 +0100
Subject: [PATCH] Update PathFollow2D when curve is changed

---
 scene/2d/path_2d.cpp | 25 +++++++++++++++++++++++++
 scene/2d/path_2d.h   |  5 +++++
 2 files changed, 30 insertions(+)

diff --git a/scene/2d/path_2d.cpp b/scene/2d/path_2d.cpp
index 09f4406ffe4..5036dd30b16 100644
--- a/scene/2d/path_2d.cpp
+++ b/scene/2d/path_2d.cpp
@@ -31,6 +31,7 @@
 #include "path_2d.h"
 
 #include "core/math/geometry_2d.h"
+#include "scene/main/timer.h"
 
 #ifdef TOOLS_ENABLED
 #include "editor/editor_scale.h"
@@ -171,6 +172,12 @@ void Path2D::_curve_changed() {
 	}
 
 	queue_redraw();
+	for (int i = 0; i < get_child_count(); i++) {
+		PathFollow2D *follow = Object::cast_to<PathFollow2D>(get_child(i));
+		if (follow) {
+			follow->path_changed();
+		}
+	}
 }
 
 void Path2D::set_curve(const Ref<Curve2D> &p_curve) {
@@ -200,6 +207,14 @@ void Path2D::_bind_methods() {
 
 /////////////////////////////////////////////////////////////////////////////////
 
+void PathFollow2D::path_changed() {
+	if (update_timer && !update_timer->is_stopped()) {
+		update_timer->start();
+	} else {
+		_update_transform();
+	}
+}
+
 void PathFollow2D::_update_transform() {
 	if (!path) {
 		return;
@@ -230,6 +245,16 @@ void PathFollow2D::_update_transform() {
 
 void PathFollow2D::_notification(int p_what) {
 	switch (p_what) {
+		case NOTIFICATION_READY: {
+			if (Engine::get_singleton()->is_editor_hint()) {
+				update_timer = memnew(Timer);
+				update_timer->set_wait_time(0.2);
+				update_timer->set_one_shot(true);
+				update_timer->connect("timeout", callable_mp(this, &PathFollow2D::_update_transform));
+				add_child(update_timer, false, Node::INTERNAL_MODE_BACK);
+			}
+		} break;
+
 		case NOTIFICATION_ENTER_TREE: {
 			path = Object::cast_to<Path2D>(get_parent());
 			if (path) {
diff --git a/scene/2d/path_2d.h b/scene/2d/path_2d.h
index 884743dd2a4..89c77c49ebf 100644
--- a/scene/2d/path_2d.h
+++ b/scene/2d/path_2d.h
@@ -34,6 +34,8 @@
 #include "scene/2d/node_2d.h"
 #include "scene/resources/curve.h"
 
+class Timer;
+
 class Path2D : public Node2D {
 	GDCLASS(Path2D, Node2D);
 
@@ -65,6 +67,7 @@ public:
 private:
 	Path2D *path = nullptr;
 	real_t progress = 0.0;
+	Timer *update_timer = nullptr;
 	real_t h_offset = 0.0;
 	real_t v_offset = 0.0;
 	real_t lookahead = 4.0;
@@ -81,6 +84,8 @@ protected:
 	static void _bind_methods();
 
 public:
+	void path_changed();
+
 	void set_progress(real_t p_progress);
 	real_t get_progress() const;