Various fixes and improvements

- Fix NaN when two handles are at the some position
- Add option to Ropesim menu to reset the rope
- Add function to RopeHandle to use the nearest rope position to a given
  point
- Fix RopeHandle not updating its target index when the rope segment
  count changes
- Make RopeHandle update its strength continously to prevent two handles
  overwriting each other's strength if they share the same rope
  position.

Author: mphe

demo/addons/ropesim/RopeHandle.gd

@@ -52,6 +52,10 @@ func _on_pre_update() -> void:
     on_before_update.emit()
     var rope: Rope = _helper.target_rope
 
+    # The point weight is set here instead of _update_state() to ensure that handles do not
+    # overwrite each other's strength values if they coincidentally target the same point index.
+    rope.set_point_simulation_weight(_target_idx, 1.0 - strength)
+
     # Only use this method if this is not the last point.
     if precise and _target_idx < rope.get_num_points() - 1:
         # TODO: Consider creating a corresponding function in Rope.gd for universal access, e.g. set_point_interpolated().
@@ -99,7 +103,7 @@ func get_enable() -> bool:
 
 
 func set_strength(value: float) -> void:
-    strength = value
+    strength = clampf(value, 0.0, 1.0)
     _update_state_current_rope()
 
 
@@ -108,9 +112,30 @@ func set_rope_position(value: float) -> void:
     _update_state_current_rope()
 
 
+## Determine the nearest position on the rope and use it as [member RopeHandle.rope_position].
+func use_nearest_position() -> void:
+    use_nearest_position_to_point(global_position)
+
+
+## Determine the nearest position on the rope to the given point and use it as [member RopeHandle.rope_position].
+func use_nearest_position_to_point(point: Vector2) -> void:
+    var rope := _helper.target_rope
+    if rope:
+        # TODO: Determine precise percentage, not just nearest index
+        var idx := rope.get_nearest_point_index(point)
+        var perc := rope.get_point_perc(idx)
+        rope_position = perc
+
+
 func _on_rope_assigned(old: Rope) -> void:
     _update_state(old)
 
+    if old:
+        old.on_point_count_changed.disconnect(_on_point_count_changed)
+
+    if _helper.target_rope:
+        _helper.target_rope.on_point_count_changed.connect(_on_point_count_changed)
+
 
 func _update_state_current_rope() -> void:
     _update_state(_helper.target_rope)
@@ -124,14 +149,14 @@ func _update_state(old_rope: Rope) -> void:
 
     var rope := _helper.target_rope
 
-    # Compute and apply new state
     if rope:
         _target_idx = rope.get_point_index(rope_position)
-        # TODO: Maybe set this value in _on_pre_update() so if it gets overwritten by another
-        # handle, it will be automatically restored when the other handle targets a different position again.
-        rope.set_point_simulation_weight(_target_idx, 1.0 - clampf(strength, 0.0, 1.0))
 
 
 func _restore_state(rope: Rope) -> void:
     if rope:
         rope.set_point_simulation_weight(_target_idx, 1.0)
+
+
+func _on_point_count_changed() -> void:
+    _update_state_current_rope()

demo/addons/ropesim/RopeInteraction.gd

@@ -94,10 +94,8 @@ func _on_after_update() -> void:
 
 ## Determine the nearest position on the rope to the target node and use it as [member RopeInteraction.rope_position].
 func use_nearest_position() -> void:
-    # TODO: Determine precise percentage, not just nearest index
-    var idx := rope.get_nearest_point_index(target_node.global_position)
-    var perc := rope.get_point_perc(idx)
-    rope_position = perc
+    _handle.use_nearest_position_to_point(target_node.global_position)
+    rope_position = _handle.rope_position
 
 
 ## Snaps the target node to the current position on the rope.

demo/addons/ropesim/plugin.gd

@@ -2,9 +2,12 @@
 extends EditorPlugin
 
 const MENU_INDEX_UPDATE_IN_EDITOR = 0
+const MENU_INDEX_RESET_ROPE = 1
 
 var _menu_toolbox: HBoxContainer
 var _menu_popup: PopupMenu
+var _edited_object: Node
+
 
 func _enter_tree() -> void:
     _build_gui()
@@ -28,8 +31,10 @@ func _handles(object: Object) -> bool:
     )
 
 
-func _edit(_object: Object) -> void:
+func _edit(object: Object) -> void:
+    _edited_object = object
     _menu_toolbox.show()
+    _menu_popup.set_item_disabled(MENU_INDEX_RESET_ROPE, not object is Rope)
 
 
 func _build_gui() -> void:
@@ -43,6 +48,8 @@ func _build_gui() -> void:
     _menu_popup = menu_button.get_popup()
     _menu_popup.add_check_item("Preview in Editor")
     _menu_popup.set_item_checked(MENU_INDEX_UPDATE_IN_EDITOR, NativeRopeServer.update_in_editor)
+    _menu_popup.add_item("Reset Rope")
+    _menu_popup.set_item_tooltip(MENU_INDEX_RESET_ROPE, "Reset the selected rope into its base position.")
     _menu_popup.connect("id_pressed", self._menu_item_clicked)
 
 
@@ -52,6 +59,10 @@ func _menu_item_clicked(idx: int) -> void:
             var value := not _menu_popup.is_item_checked(idx)
             _menu_popup.set_item_checked(MENU_INDEX_UPDATE_IN_EDITOR, value)
             NativeRopeServer.update_in_editor = value
+        MENU_INDEX_RESET_ROPE:
+            var rope := _edited_object as Rope
+            if rope:
+                rope.reset()
 
 
 func _free_gui() -> void:

src/NativeRopeContext.cpp

@@ -157,7 +157,7 @@ static void constraint_segment(Vector2* point_a, Vector2* point_b, float weight_
     const Vector2 diff = *point_b - *point_a;
     const float distance = diff.length();
     const float error = (seg_length - distance) * 0.5f;
-    const Vector2 dir = error * (diff / distance);
+    const Vector2 dir = error * (diff / Math::max(distance, 0.001f));
 
     // If one point has a weight < 1.0, the other point must compensate the difference in
     // relation to its own weight.