Add ProjectileEffect base class and basic functionality

projectiles/double_laser.gd

@@ -0,0 +1,24 @@
+class_name EffectDoubleLaser
+extends ProjectileEffect
+
+var Projectile : PackedScene = preload("res://units/projectile.tscn")
+
+@export var laser_offset = Vector2(0, -50)
+const is_double_laser = true
+
+func check_not_double_laser(effect: PackedScene) -> bool:
+	# TODO:: Filter on type? This implementation is Bad
+	if "is_double_laser" in effect:
+		return not effect.is_double_laser
+
+	# TODO:: Hacky? but const on the node does not work for packed scenes
+	return effect.resource_path != "res://projectiles/double_laser.tscn"
+
+func modify_creation(owner: Node, projectile_effects: Array, transform: Transform2D):
+		var p = Projectile.instantiate()
+		# TODO:: Stacking double-lasers? would mean we only want to filter 1 out of this list.
+		var non_recursive_effects = projectile_effects.filter(check_not_double_laser)
+		var doubled_transform = transform
+		# TODO:: Do we want to offset the laser, or do we want to angle out of the same point of origin?
+		doubled_transform.origin += laser_offset
+		p.spawn(owner, non_recursive_effects, doubled_transform)

projectiles/double_laser.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3 uid="uid://dgp68vbl25onx"]
+
+[ext_resource type="Script" path="res://projectiles/double_laser.gd" id="1_wqupk"]
+
+[node name="DoubleLaser" type="Node"]
+script = ExtResource("1_wqupk")

projectiles/fast_laser.tscn

@@ -0,0 +1,7 @@
+[gd_scene load_steps=2 format=3 uid="uid://dj6jn0ia62yba"]
+
+[ext_resource type="Script" path="res://projectiles/projectile_effect.gd" id="1_jlt11"]
+
+[node name="FastLaser" type="Node"]
+script = ExtResource("1_jlt11")
+speed_modifier = 3

projectiles/huge_laser.gd

@@ -0,0 +1,2 @@
+class_name HugeLaser
+extends ProjectileEffect

projectiles/huge_laser.tscn

@@ -0,0 +1,7 @@
+[gd_scene load_steps=2 format=3 uid="uid://i6l7jkbauvmf"]
+
+[ext_resource type="Script" path="res://projectiles/huge_laser.gd" id="1_ouvu5"]
+
+[node name="HugeLaser" type="Node"]
+script = ExtResource("1_ouvu5")
+scale_modifier = 10

projectiles/projectile_effect.gd

@@ -0,0 +1,71 @@
+class_name ProjectileEffect
+extends Node
+# A ProjectileEffect is a set of post-processors meant to be run on every instance of a Projectile.
+# This by itself does nothing but is meant to be extended by various types of projectile effect.
+# Each effect will compound on the others. Each function will be called by the Projectile scene,
+#    in order of Effect Priority
+# TODO:: Effect Priority as an enum? (to discourage "priority: 9999999")
+
+# Each modifier is a combination of a double value and a modification type.
+# This is to indicate if a modification is additive or multiplicitive.
+# The default for all modifiers is MULTIPLICITIVE : 1, ultimately resulting in no effect.
+# (To subtract and divide, use negative values and decimals < 1)
+enum MODIFICATION_TYPE {
+	ADD,
+	MULTIPLY
+}
+@export var effect_priority = -1
+@export var speed_modifier_type = MODIFICATION_TYPE.MULTIPLY
+@export var speed_modifier = 1
+@export var damage_modifier_type = MODIFICATION_TYPE.MULTIPLY
+@export var damage_modifier = 1
+@export var scale_modifier_type = MODIFICATION_TYPE.MULTIPLY
+@export var scale_modifier = 1
+
+
+# Modify the logic that adds the projectile as a child to the scene.
+# This can be used to change spawn locations, quantities, etc.
+func modify_creation(owner: Node, projectile_effects: Array, transform: Transform2D):
+	pass
+
+func _calculate_vector_modification(
+	base_value: Vector2,
+	modifier_value: int,
+	modifier_type: MODIFICATION_TYPE
+):
+	# TODO:: How does godot mutability work? we do NOT want to modify the original modifier
+	var local_modifier = base_value
+	if modifier_type == MODIFICATION_TYPE.MULTIPLY:
+		local_modifier *= modifier_value
+	elif modifier_type == MODIFICATION_TYPE.ADD:
+		local_modifier += modifier_value
+	return local_modifier
+
+# Modify the physics logic of the projectile. This function will be called
+#    during the _physics_process.
+# Uses exported variables by default, and should only be overridden if you're
+#    doing something really interesting.
+func modify_physics(physics_vector: Vector2) -> Vector2:
+	return _calculate_vector_modification(physics_vector, speed_modifier, speed_modifier_type)
+
+
+# Simple changes to the appearance using built-in features.
+# By default, modifies the scale of the projectile.
+func modify_appearance(scale: Vector2) -> Vector2:
+	return _calculate_vector_modification(owner.scale, scale_modifier, scale_modifier_type)
+
+
+# To change the sprite itself, elements of the animation, or otherwise add effects
+# Hard changes, rather than additions, will be subject to effect_priority.
+func modify_animation():
+	pass
+
+
+# Called when the node enters the scene tree for the first time.
+func _enter_tree():
+	var projectile = get_owner()
+	if projectile:
+		# Projectile scenes are instantiated before being added to the tree
+		# This function will effectively be called twice, but some operations
+		#    require the parent node to be present first.
+		projectile.scale_projectile(modify_appearance(projectile.scale))

projectiles/projectile_effect.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3 uid="uid://bwxewmel1e8si"]
+
+[ext_resource type="Script" path="res://projectiles/projectile_effect.gd" id="1_eosdr"]
+
+[node name="ProjectileEffect" type="Node"]
+script = ExtResource("1_eosdr")

units/enemy.gd

@@ -10,3 +10,6 @@ func _physics_process(delta):
 
 func _on_visible_on_screen_notifier_2d_screen_exited():
 	queue_free()
+
+func _on_area_entered(area):
+	queue_free()

units/enemy.tscn

@@ -1,4 +1,4 @@
-[gd_scene load_steps=4 format=3 uid="uid://4fjgeuv7aun7"]
+[gd_scene load_steps=4 format=3 uid="uid://bdsjg08y1h6yh"]
 
 [ext_resource type="Script" path="res://units/enemy.gd" id="1_6h8a0"]
 [ext_resource type="Texture2D" uid="uid://dqkvsqmwue64p" path="res://units/PNG_Parts&Spriter_Animation/Ship1/Ship1.png" id="1_ndkjl"]
@@ -13,11 +13,13 @@ script = ExtResource("1_6h8a0")
 texture = ExtResource("1_ndkjl")
 
 [node name="Area2D" type="Area2D" parent="."]
+collision_mask = 3
 
 [node name="CollisionShape2D" type="CollisionShape2D" parent="Area2D"]
 position = Vector2(0, -0.75)
 shape = SubResource("RectangleShape2D_mvxux")
 
 [node name="VisibleOnScreenNotifier2D" type="VisibleOnScreenNotifier2D" parent="."]
 
+[connection signal="area_entered" from="Area2D" to="." method="_on_area_entered"]
 [connection signal="screen_exited" from="VisibleOnScreenNotifier2D" to="." method="_on_visible_on_screen_notifier_2d_screen_exited"]

units/player.gd

@@ -9,11 +9,22 @@ const HORIZONTAL_BUFFER = 75
 
 @export var Projectile : PackedScene
 @onready var projectile_spawner = $ProjectileSpawner
+var DoubleLaserEffect : PackedScene = preload("res://projectiles/double_laser.tscn")
+var HugeLaserEffect : PackedScene = preload("res://projectiles/huge_laser.tscn")
+var FastLaserEffect : PackedScene = preload("res://projectiles/fast_laser.tscn")
 
 # Called when the node enters the scene tree for the first time.
 func _ready():
 	Projectile = load("res://units/projectile.tscn")
 
+func fire():
+	print('fired!')
+	var p = Projectile.instantiate()
+	# Effects must be instantiated for each projectile.
+	# Finding a way to manage "which effects we need to instantiate" and
+	#    "Which effects are actually on this projectile" is key
+	var effects = [DoubleLaserEffect, HugeLaserEffect, FastLaserEffect]
+	p.spawn(owner, effects, transform)
 
 # Called every frame. 'delta' is the elapsed time since the previous frame.
 func _physics_process(delta):
@@ -30,8 +41,4 @@ func _physics_process(delta):
 		position.x += HORIZONTAL_SPEED * delta
 
 	if Input.is_action_just_pressed("fire"):
-		print('fired!')
-		var p = Projectile.instantiate()
-		owner.add_child(p)
-		p.transform = projectile_spawner.global_transform
-
+		fire()

units/projectile.gd

@@ -1,13 +1,45 @@
 extends Area2D
 
 const SPEED = 750
+var projectile_effects: Array = []
 
 
-func _physics_process(delta):
-	position += transform.x * SPEED * delta
+func spawn(owner: Node, spawn_with_projectile_effects: Array, parent_transform: Transform2D):
+	# Execute any spawn modification effects for the projectile
+	print("spawned!")
+	#projectile_effects = spawn_with_projectile_effects
+	var local_transform = parent_transform
+	for effect in spawn_with_projectile_effects:
+		var instance = effect.instantiate()
+		projectile_effects.append(instance)
+		add_child(instance)
+		instance.set_owner(self)
+		instance.modify_creation(owner, spawn_with_projectile_effects, local_transform)
+	# Spawn the default projectile
+	# TODO:: Projectile spawn modification may want to prevent the default from spawning
+	#    how do?
+	owner.add_child(self)
+	projectile_effects = projectile_effects
+	transform = local_transform
+
+func scale_projectile(new_scale: Vector2):
+	$Sprite2D.scale = new_scale
+	$CollisionShape2D.scale = new_scale
+	scale = new_scale
 
+func _ready():
+	if scale != Vector2.ONE:
+		scale_projectile(scale)
+
+func _physics_process(delta):
+	var position_modifier = transform.x * SPEED * delta
+	for effect in projectile_effects:
+		position_modifier = effect.modify_physics(position_modifier)
+	set_position(position + position_modifier)
 
 func _on_area_entered(area):
 	# TODO: apply effects on enemy hit. For now just despawn.
 	queue_free()
-	area.owner.queue_free()
+
+func _integrate_forces(delta):
+	scale = Vector2(100, 100)

units/projectile.tscn

@@ -8,6 +8,7 @@ radius = 4.0
 
 [node name="Projectile" type="Area2D"]
 position = Vector2(68, 1)
+collision_layer = 2
 script = ExtResource("1_t6pyo")
 
 [node name="Sprite2D" type="Sprite2D" parent="."]