Player: Add optional double jump

If enabled, the player can jump a second time while still in the air from a
previous jump. A crude shower of particles is emitted to indicate ✨ magic ✨.

components/player/player.tscn

@@ -14,6 +14,21 @@ floor_constant_speed = true
 floor_snap_length = 32.0
 script = ExtResource("1_w3ms2")
 
+[node name="DoubleJumpParticles" type="CPUParticles2D" parent="."]
+unique_name_in_owner = true
+emitting = false
+amount = 60
+lifetime = 0.2
+one_shot = true
+explosiveness = 0.54
+randomness = 0.25
+emission_shape = 1
+emission_sphere_radius = 36.72
+particle_flag_align_y = true
+gravity = Vector2(0, 1)
+scale_amount_max = 5.0
+color = Color(1, 1, 0, 1)
+
 [node name="AnimatedSprite2D" type="AnimatedSprite2D" parent="."]
 unique_name_in_owner = true
 position = Vector2(0, -64)

scripts/player.gd

@@ -31,18 +31,25 @@ extends CharacterBody2D
 ## a small positive number to allow the player a little margin for error.
 @export_range(0, 0.5, 1 / 60.0, "suffix:s") var jump_buffer: float = 5.0 / 60.0
 
+## Can your character jump a second time while still in the air?
+@export var double_jump: bool = false
+
 # If positive, the player is either on the ground, or left the ground less than this long ago
 var coyote_timer: float = 0
 
 # If positive, the player pressed jump this long ago
 var jump_buffer_timer: float = 0
 
+# If true, the player is already jumping and can perform a double-jump
+var double_jump_armed: bool = false
+
 # Get the gravity from the project settings to be synced with RigidBody nodes.
 var gravity = ProjectSettings.get_setting("physics/2d/default_gravity")
 var original_position: Vector2
 
 @onready var _sprite: AnimatedSprite2D = %AnimatedSprite2D
 @onready var _initial_sprite_frames: SpriteFrames = %AnimatedSprite2D.sprite_frames
+@onready var _double_jump_particles: CPUParticles2D = %DoubleJumpParticles
 
 
 func _set_sprite_frames(new_sprite_frames):
@@ -87,14 +94,20 @@ func _physics_process(delta):
 	# Handle jump
 	if is_on_floor():
 		coyote_timer = (coyote_time + delta)
+		double_jump_armed = false
 
 	if Input.is_action_just_pressed("ui_accept"):
 		jump_buffer_timer = (jump_buffer + delta)
 
-	if jump_buffer_timer > 0 and coyote_timer > 0:
+	if jump_buffer_timer > 0 and (double_jump_armed or coyote_timer > 0):
 		velocity.y = jump_velocity
 		coyote_timer = 0
 		jump_buffer_timer = 0
+		if double_jump_armed:
+			double_jump_armed = false
+			_double_jump_particles.emitting = true
+		elif double_jump:
+			double_jump_armed = true
 
 	# Reduce velocity if the player lets go of the jump key before the apex.
 	# This allows controlling the height of the jump.