Add on_pre_pre and on_post_post signals to NativeRopeServer

This allows to hook in before RopeHandles or RopeAnchors execute.
Also updated documentation and the rope_pulling example to make use of
this feature to prevent a 1-frame lag.

Author: mphe

demo/addons/ropesim/RopeAnchor.gd

@@ -3,6 +3,7 @@ extends BaseRopeTool2D
 class_name RopeAnchor
 
 ## Can be used to attach nodes at certain positions on a target rope.
+## Updates during the on_post_update signal of NativeRopeServer.
 
 ## Gets emitted just after applying the position. This happens always during _physics_process().
 signal on_after_update()

demo/addons/ropesim/RopeHandle.gd

@@ -3,6 +3,7 @@ extends BaseRopeTool2D
 class_name RopeHandle
 
 ## Can be used to control, animate or fixate points on a target rope.
+## Updates during the on_pre_update signal of NativeRopeServer.
 
 ## Gets emitted just before applying the position. This happens always during _physics_process().
 signal on_before_update()

demo/addons/ropesim/RopeToolHelper.gd

@@ -5,7 +5,9 @@ class_name RopeToolHelper
 ## It contains boilerplate for registering/unregistering to/from NativeRopeServer when needed.
 
 const UPDATE_HOOK_POST = "on_post_update"
+const UPDATE_HOOK_POST_POST = "on_post_post_update"
 const UPDATE_HOOK_PRE = "on_pre_update"
+const UPDATE_HOOK_PRE_PRE = "on_pre_pre_update"
 
 ## Emitted when the assigned rope has been changed, i.e. to a new rope or null.
 signal on_rope_assigned(old: Rope)

demo/rope_examples/scripts/character_body_2d.gd

@@ -4,7 +4,15 @@ extends CharacterBody2D
 @export var speed: float = 300.0
 
 
-func _physics_process(_delta: float) -> void:
+func _ready() -> void:
+    # To prevent a 1-frame lag, we connect to the pre_pre event, so the movement code always runs
+    # before RopeHandles, RopeAnchors and the rope simulation itself.
+    # It is not necessary to do this instead of just using _physics_process() but it should
+    # demonstrate how to solve the lag.
+    NativeRopeServer.on_pre_pre_update.connect(_update)
+
+
+func _update() -> void:
     var wishdir := Vector2()
 
     if use_arrow_keys:

src/NativeRopeServer.cpp

@@ -46,6 +46,8 @@ void NativeRopeServer::_bind_methods()
     ADD_PROPERTY(PropertyInfo(Variant::BOOL, "update_in_editor"), "set_update_in_editor", "get_update_in_editor");
     ADD_SIGNAL(MethodInfo("on_post_update"));
     ADD_SIGNAL(MethodInfo("on_pre_update"));
+    ADD_SIGNAL(MethodInfo("on_post_post_update"));
+    ADD_SIGNAL(MethodInfo("on_pre_pre_update"));
 }
 
 void NativeRopeServer::register_rope(Node2D* rope)
@@ -119,6 +121,7 @@ void NativeRopeServer::_start_stop_process()
 
 void NativeRopeServer::_on_physics_frame()
 {
+    emit_signal("on_pre_pre_update");
     emit_signal("on_pre_update");
     const double delta = _tree->get_root()->get_physics_process_delta_time();
     NativeRopeContext context;
@@ -140,6 +143,7 @@ void NativeRopeServer::_on_physics_frame()
 
     _last_time = (float)(Time::get_singleton()->get_ticks_usec() - start) / 1000.f;
     emit_signal("on_post_update");
+    emit_signal("on_post_post_update");
 }
 
 float NativeRopeServer::get_computation_time() const