Make Repel action a bit more generic (#2088)

The repel mechanic was initially intended for the ink blobs, then to any
projectile. But we can now consider a repel action that affects more
game elements.

----

### Physics layers: Rename projectile to repellable

Similar to the "hookable" layer. To make the repel mechanic a bit more
generic.

Update the enum and the references in eldrune StoryQuest.

----

### Project: Set default gravity to zero

Otherwise adding a RigidBody2D to the scene, the bodies go down
until they hit a wall.

Setting the default gravity to zero, the object looks like it's on
the ground.

----

### Repel mechanic: Make it work with any Node2D

That has a got_repelled() method.

So far we've been assuming a Projectile node for the on_body_entered
handler of the Repel area.
But the Area2D.body_entered signal is sent with the body: Node2D
parameter (which in reality
can be a PhysicsBody2D or a TileMap).

So use duck typing and also rename the expected method to
"got_repelled". Also, call it
with the direction of the repel. Previously the Player was passed and
the repel direction
was calculated on the called node.

This makes the repel ability more generic.

Also adapt the eldrune_projectile.gd script.

----

### Player repel: Split to its own scene

So the action can be used in other entities of the game, like in NPCs.
Export a player controlled boolean
for that same reason.

Move all animation tracks related to the repel action, except the player
animation, to its own AnimationPlayer.
These two animations (the player moving the button and the repel air
stream growing) should be kept in sync.

----

### Add examples of custom repellable objects

Add a test gym scene with multiple things to repel:

- A box that can be pushed along a grid.
- Bouncy ball.
- A lever that can be swithed in the repelled direction.

----

Resolve #2059

Author: manuq

project.godot

@@ -294,10 +294,14 @@ locale/translations_pot_files=PackedStringArray("res://scenes/menus/title/compon
 2d_physics/layer_6="interactable"
 2d_physics/layer_7="players hitbox"
 2d_physics/layer_8="enemies hitbox"
-2d_physics/layer_9="projectiles"
+2d_physics/layer_9="repellable"
 2d_physics/layer_10="non_walkable_floor"
 2d_physics/layer_13="hookable"
 
+[physics]
+
+2d/default_gravity=0.0
+
 [rendering]
 
 textures/canvas_textures/default_texture_filter=0

scenes/game_elements/characters/player/components/animation_player.gd

@@ -2,8 +2,6 @@
 # SPDX-License-Identifier: MPL-2.0
 extends AnimationPlayer
 
-const REPEL_ANTICIPATION_TIME: float = 0.3
-
 var _is_player_running: bool
 
 @onready var player: Player = owner
@@ -62,7 +60,7 @@ func _on_player_repel_repelling_changed(repelling: bool) -> void:
 	# directly to the action.
 	speed_scale = original_speed_scale
 	play(&"repel")
-	seek(REPEL_ANTICIPATION_TIME, false, false)
+	seek(player_repel.REPEL_ANTICIPATION_TIME, false, false)
 
 
 func _on_player_hook_string_thrown() -> void:

scenes/game_elements/characters/player/components/player_repel.gd

@@ -6,28 +6,62 @@ extends Node2D
 ## Emitted when the repel starts or stops.
 signal repelling_changed(repelling: bool)
 
+const REPEL_ANTICIPATION_TIME: float = 0.3
+
+## If false, [member repelling] should be changed by other means.
+@export var player_controlled: bool = true
+
+## If controlled by the player, which input action triggers the repel.
 @export var input_action: StringName = &"repel"
 
 ## Current state of the repel.
-var repelling: bool = false:
+@export var repelling: bool = false:
 	set = _set_repelling
 
 @onready var air_stream: Area2D = %AirStream
-
-@onready var player: Player = self.owner as Player
+@onready var repel_animation: AnimationPlayer = %RepelAnimation
 
 
 func _set_repelling(new_repelling: bool) -> void:
 	repelling = new_repelling
+	if not is_node_ready():
+		return
 	repelling_changed.emit(repelling)
+	if repelling:
+		_animate()
 
 
 func _unhandled_input(_event: InputEvent) -> void:
+	if not player_controlled:
+		return
 	if Input.is_action_just_pressed(input_action):
 		repelling = true
 	elif Input.is_action_just_released(input_action):
 		repelling = false
 
 
-func _on_air_stream_body_entered(body: Projectile) -> void:
-	body.got_hit(owner)
+func repel_once() -> void:
+	repelling = true
+	repelling = false
+
+
+func _on_air_stream_body_entered(body: Node2D) -> void:
+	if body.has_method("got_repelled"):
+		var direction := global_position.direction_to(body.global_position)
+		body.got_repelled(direction)
+
+
+func _animate() -> void:
+	# The repel animation is already ongoing. Prevent starting it again by smashing the buttons.
+	if repel_animation.current_animation == &"repel":
+		return
+
+	# Repel animation is being played for the first time. So skip the anticipation and go
+	# directly to the action.
+	repel_animation.play(&"repel")
+	repel_animation.seek(REPEL_ANTICIPATION_TIME, false, false)
+
+
+func _on_repel_animation_animation_finished(anim_name: StringName) -> void:
+	if anim_name == &"repel" and repelling:
+		repel_animation.play(&"repel")

scenes/game_elements/characters/player/components/player_repel.tscn

@@ -0,0 +1,188 @@
+[gd_scene format=3 uid="uid://cl06pid826dtg"]
+
+[ext_resource type="Script" uid="uid://kni2yl26matc" path="res://scenes/game_elements/characters/player/components/player_repel.gd" id="1_y1fpu"]
+[ext_resource type="Texture2D" uid="uid://dda0lxfswrncy" path="res://scenes/game_elements/characters/player/components/blow.png" id="2_ochor"]
+[ext_resource type="AudioStream" uid="uid://crfylo055wa8e" path="res://scenes/game_elements/characters/player/components/blow.wav" id="3_bvany"]
+
+[sub_resource type="CircleShape2D" id="CircleShape2D_h17s1"]
+radius = 20.0
+
+[sub_resource type="CanvasItemMaterial" id="CanvasItemMaterial_je7p5"]
+blend_mode = 1
+
+[sub_resource type="Animation" id="Animation_5lbww"]
+resource_name = "RESET"
+tracks/0/type = "value"
+tracks/0/imported = false
+tracks/0/enabled = true
+tracks/0/path = NodePath("AirStream/AirStreamCollision:disabled")
+tracks/0/interp = 1
+tracks/0/loop_wrap = true
+tracks/0/keys = {
+"times": PackedFloat32Array(0),
+"transitions": PackedFloat32Array(1),
+"update": 1,
+"values": [true]
+}
+tracks/1/type = "value"
+tracks/1/imported = false
+tracks/1/enabled = true
+tracks/1/path = NodePath("AirStream/AirStreamCollision:shape:radius")
+tracks/1/interp = 1
+tracks/1/loop_wrap = true
+tracks/1/keys = {
+"times": PackedFloat32Array(0),
+"transitions": PackedFloat32Array(1),
+"update": 0,
+"values": [20.0]
+}
+tracks/2/type = "value"
+tracks/2/imported = false
+tracks/2/enabled = true
+tracks/2/path = NodePath("AirStream/Sprite2D:visible")
+tracks/2/interp = 1
+tracks/2/loop_wrap = true
+tracks/2/keys = {
+"times": PackedFloat32Array(0),
+"transitions": PackedFloat32Array(1),
+"update": 1,
+"values": [false]
+}
+tracks/3/type = "value"
+tracks/3/imported = false
+tracks/3/enabled = true
+tracks/3/path = NodePath("AirStream/Sprite2D:scale")
+tracks/3/interp = 1
+tracks/3/loop_wrap = true
+tracks/3/keys = {
+"times": PackedFloat32Array(0),
+"transitions": PackedFloat32Array(1),
+"update": 0,
+"values": [Vector2(0.12577, 0.12577)]
+}
+tracks/4/type = "value"
+tracks/4/imported = false
+tracks/4/enabled = true
+tracks/4/path = NodePath("AirStream/Sprite2D:modulate")
+tracks/4/interp = 1
+tracks/4/loop_wrap = true
+tracks/4/keys = {
+"times": PackedFloat32Array(0),
+"transitions": PackedFloat32Array(1),
+"update": 0,
+"values": [Color(1, 1, 1, 1)]
+}
+
+[sub_resource type="Animation" id="Animation_cvb4d"]
+resource_name = "repel"
+length = 0.6
+tracks/0/type = "value"
+tracks/0/imported = false
+tracks/0/enabled = true
+tracks/0/path = NodePath("AirStream/AirStreamCollision:disabled")
+tracks/0/interp = 1
+tracks/0/loop_wrap = true
+tracks/0/keys = {
+"times": PackedFloat32Array(0, 0.3, 0.6),
+"transitions": PackedFloat32Array(1, 1, 1),
+"update": 1,
+"values": [true, false, true]
+}
+tracks/1/type = "value"
+tracks/1/imported = false
+tracks/1/enabled = true
+tracks/1/path = NodePath("AirStream/AirStreamCollision:shape:radius")
+tracks/1/interp = 1
+tracks/1/loop_wrap = true
+tracks/1/keys = {
+"times": PackedFloat32Array(0.3, 0.6),
+"transitions": PackedFloat32Array(1, 1),
+"update": 0,
+"values": [20.0, 150.0]
+}
+tracks/2/type = "value"
+tracks/2/imported = false
+tracks/2/enabled = true
+tracks/2/path = NodePath("AirStream/Sprite2D:visible")
+tracks/2/interp = 1
+tracks/2/loop_wrap = true
+tracks/2/keys = {
+"times": PackedFloat32Array(0, 0.3, 0.6),
+"transitions": PackedFloat32Array(1, 1, 1),
+"update": 1,
+"values": [false, true, false]
+}
+tracks/3/type = "value"
+tracks/3/imported = false
+tracks/3/enabled = true
+tracks/3/path = NodePath("AirStream/Sprite2D:scale")
+tracks/3/interp = 1
+tracks/3/loop_wrap = true
+tracks/3/keys = {
+"times": PackedFloat32Array(0.3, 0.6),
+"transitions": PackedFloat32Array(1, 1),
+"update": 0,
+"values": [Vector2(0.12577, 0.12577), Vector2(1, 1)]
+}
+tracks/4/type = "value"
+tracks/4/imported = false
+tracks/4/enabled = true
+tracks/4/path = NodePath("AirStream/Sprite2D:modulate")
+tracks/4/interp = 1
+tracks/4/loop_wrap = true
+tracks/4/keys = {
+"times": PackedFloat32Array(0.3, 0.5, 0.6),
+"transitions": PackedFloat32Array(2, 0.5, 0.5),
+"update": 0,
+"values": [Color(1, 1, 1, 0), Color(1, 1, 1, 0.456), Color(1, 1, 1, 0)]
+}
+tracks/5/type = "audio"
+tracks/5/imported = false
+tracks/5/enabled = true
+tracks/5/path = NodePath("AirStream/AudioStreamPlayer2D")
+tracks/5/interp = 1
+tracks/5/loop_wrap = true
+tracks/5/keys = {
+"clips": [{
+"end_offset": 0.0,
+"start_offset": 0.0,
+"stream": ExtResource("3_bvany")
+}],
+"times": PackedFloat32Array(0.3)
+}
+tracks/5/use_blend = true
+
+[sub_resource type="AnimationLibrary" id="AnimationLibrary_ubfef"]
+_data = {
+&"RESET": SubResource("Animation_5lbww"),
+&"repel": SubResource("Animation_cvb4d")
+}
+
+[node name="PlayerRepel" type="Node2D" unique_id=1324972992]
+script = ExtResource("1_y1fpu")
+
+[node name="AirStream" type="Area2D" parent="." unique_id=1185536811]
+unique_name_in_owner = true
+collision_layer = 0
+collision_mask = 256
+
+[node name="AirStreamCollision" type="CollisionShape2D" parent="AirStream" unique_id=482921981]
+unique_name_in_owner = true
+shape = SubResource("CircleShape2D_h17s1")
+disabled = true
+
+[node name="Sprite2D" type="Sprite2D" parent="AirStream" unique_id=1723853226]
+visible = false
+material = SubResource("CanvasItemMaterial_je7p5")
+scale = Vector2(0.12577, 0.12577)
+texture = ExtResource("2_ochor")
+
+[node name="AudioStreamPlayer2D" type="AudioStreamPlayer2D" parent="AirStream" unique_id=1428086503]
+bus = &"SFX"
+
+[node name="RepelAnimation" type="AnimationPlayer" parent="." unique_id=2103763625]
+unique_name_in_owner = true
+libraries/ = SubResource("AnimationLibrary_ubfef")
+
+[connection signal="body_entered" from="AirStream" to="." method="_on_air_stream_body_entered"]
+[connection signal="animation_finished" from="RepelAnimation" to="." method="_on_repel_animation_animation_finished"]