Add example on how to attach a RigidBody to a rope

Also adds a input_node_override property to RopeInteraction to allow
specifying a separate node for position input and position output.
This is needed when dealing with RigidBodys which use a PinJoint as
target node and the RigidBody as input node overide.

Author: mphe

demo/addons/ropesim/RopeInteraction.gd

@@ -4,8 +4,14 @@ class_name RopeInteraction
 
 ## Handles mutual interaction of a target node with a rope.
 ## Useful for rope grabbing or pulling mechanics where an object should be able to affect the rope
-## while also being constrained by it.
-## Uses [RopeHandle] and [RopeAnchor] internally.
+## while also being constrained by it.[br]
+## [br]
+## Internally, a [RopeHandle] and a [RopeAnchor] is used to update the rope and retrieve the new
+## position afterwards.[br]
+## It essentially works by running the following three steps every frame:[br]
+## 1. Set [RopeHandle] position to target node position.[br]
+## 2. Wait for rope simulation to be finished.[br]
+## 3. Set target node position to [RopeAnchor] position.
 
 ## Emitted when the target node should be moved and [member RopeInteraction.position_update_mode] is [enum RopeInteraction.Signal].
 signal on_movement_request(target: Node2D, anchor: RopeAnchor)
@@ -27,14 +33,17 @@ enum PositionUpdateMode {
 ## Enable or disable.
 @export var enable: bool = true : set = set_enable
 
-## Determines how the position of the target node is updated.
+## Determines how the position of the target node should be updated.
 @export var position_update_mode: PositionUpdateMode = PositionUpdateMode.EmitSignal
 
 ## Target node that should be attached to the rope.
 @export var target_node: Node2D
 
+## (Optional) Use the given node instead of the target node to update the rope point's position.
+## If set, the target node will only be snapped to the rope, but it will not affect it.
+@export var input_node_override: Node2D
+
 ## Target rope.
-# @export_node_path("Rope") var rope: NodePath : set = set_rope
 @export var rope: Rope : set = set_rope
 
 ## Position on the rope between 0 and 1.
@@ -61,9 +70,13 @@ func _init() -> void:
 func _enter_tree() -> void:
     set_rope(rope)
 
+    if not target_node:
+        push_warning("RopeInteraction: No target node selected -> Disabling")
+        enable = false
+
 
 func _on_before_update() -> void:
-    _handle.global_position = target_node.global_position
+    _handle.global_position = (input_node_override if input_node_override else target_node).global_position
 
 
 func _on_after_update() -> void:

demo/rope_examples/benchmark.tscn

@@ -10,8 +10,8 @@ offset_left = 449.0
 offset_top = -1.0
 offset_right = 509.0
 offset_bottom = 22.0
-text = "192 Ropes
-2.82 ms"
+text = "384 Ropes
+3.99 ms"
 script = ExtResource("2_ms00a")
 
 [node name="Node2D9" type="Node2D" parent="."]

demo/rope_examples/rigidbody_rope_attachment.tscn

@@ -0,0 +1,51 @@
+[gd_scene load_steps=5 format=3 uid="uid://gex7loccj42u"]
+
+[ext_resource type="PackedScene" uid="uid://beuu34gtk2nhm" path="res://rope_examples/scripts/rope_with_rigidbody.tscn" id="1_aij5x"]
+[ext_resource type="Texture2D" uid="uid://criwv6nuivcxy" path="res://rope_examples/icon.svg" id="3_xivx8"]
+[ext_resource type="Script" path="res://rope_examples/scripts/character_body_2d.gd" id="5_du4tb"]
+
+[sub_resource type="RectangleShape2D" id="RectangleShape2D_6gqpg"]
+size = Vector2(64, 64)
+
+[node name="Node2D" type="Node2D"]
+
+[node name="rope_with_body" parent="." instance=ExtResource("1_aij5x")]
+
+[node name="rope_with_body2" parent="." instance=ExtResource("1_aij5x")]
+position = Vector2(498, 0)
+
+[node name="rope_with_body3" parent="." instance=ExtResource("1_aij5x")]
+position = Vector2(589, 0)
+
+[node name="Player" type="CharacterBody2D" parent="."]
+process_physics_priority = -100
+position = Vector2(227, 253)
+collision_mask = 0
+motion_mode = 1
+script = ExtResource("5_du4tb")
+metadata/_edit_group_ = true
+
+[node name="CollisionShape2D" type="CollisionShape2D" parent="Player"]
+shape = SubResource("RectangleShape2D_6gqpg")
+
+[node name="Icon" type="Sprite2D" parent="Player"]
+scale = Vector2(0.5, 0.5)
+texture = ExtResource("3_xivx8")
+
+[node name="Label2" type="Label" parent="Player"]
+offset_left = -46.0
+offset_top = 36.0
+offset_right = 42.0
+offset_bottom = 59.0
+text = "WSAD"
+horizontal_alignment = 1
+
+[node name="Label" type="Label" parent="."]
+offset_left = 10.0
+offset_top = 481.0
+offset_right = 852.0
+offset_bottom = 504.0
+text = "Basic example on how to attach a RigidBody to a rope and enabling corresponding physics reactions.
+
+A PinJoint2D fixates the RigidBody to the rope.
+A RopeInteraction uses the RigidBody to control the rope and updates the PinJoint2D respectively."

demo/rope_examples/scripts/rope_with_rigidbody.tscn

@@ -0,0 +1,50 @@
+[gd_scene load_steps=6 format=3 uid="uid://beuu34gtk2nhm"]
+
+[ext_resource type="Script" path="res://addons/ropesim/Rope.gd" id="1_4r73y"]
+[ext_resource type="Script" path="res://addons/ropesim/RopeInteraction.gd" id="2_1yts0"]
+[ext_resource type="Texture2D" uid="uid://criwv6nuivcxy" path="res://rope_examples/icon.svg" id="3_uwcl5"]
+
+[sub_resource type="PhysicsMaterial" id="PhysicsMaterial_nwm6u"]
+
+[sub_resource type="RectangleShape2D" id="RectangleShape2D_3g7xa"]
+size = Vector2(64, 64)
+
+[node name="rope_with_body" type="Node2D"]
+position = Vector2(408, 0)
+
+[node name="Rope" type="Node2D" parent="."]
+script = ExtResource("1_4r73y")
+num_segments = 15
+rope_length = 250.0
+gravity = 75.0
+num_constraint_iterations = 20
+
+[node name="RopeInteraction" type="Node" parent="." node_paths=PackedStringArray("target_node", "input_node_override", "rope")]
+script = ExtResource("2_1yts0")
+position_update_mode = 0
+target_node = NodePath("../pin_point")
+input_node_override = NodePath("../hanging_rigidbody")
+rope = NodePath("../Rope")
+
+[node name="pin_point" type="CharacterBody2D" parent="."]
+position = Vector2(0, 250)
+collision_layer = 0
+collision_mask = 0
+motion_mode = 1
+
+[node name="PinJoint2D" type="PinJoint2D" parent="pin_point"]
+node_a = NodePath("../../hanging_rigidbody")
+node_b = NodePath("..")
+
+[node name="hanging_rigidbody" type="RigidBody2D" parent="."]
+position = Vector2(0, 250)
+mass = 5.0
+physics_material_override = SubResource("PhysicsMaterial_nwm6u")
+metadata/_edit_group_ = true
+
+[node name="CollisionShape2D" type="CollisionShape2D" parent="hanging_rigidbody"]
+shape = SubResource("RectangleShape2D_3g7xa")
+
+[node name="Icon" type="Sprite2D" parent="hanging_rigidbody"]
+scale = Vector2(0.5, 0.5)
+texture = ExtResource("3_uwcl5")