add shader to show that enemy got hit, also parameterize damage on enemy

entities/enemy.tscn

@@ -1,7 +1,14 @@
-[gd_scene load_steps=4 format=3 uid="uid://32uqp2kt3dy4"]
+[gd_scene load_steps=6 format=3 uid="uid://32uqp2kt3dy4"]
 
 [ext_resource type="Script" path="res://scripts/enemy.gd" id="1_yqwu2"]
 [ext_resource type="Texture2D" uid="uid://bivyscdevv7ye" path="res://art/enemy/enemy-01.png" id="2_jkjfl"]
+[ext_resource type="Shader" path="res://shaders/hitflash.gdshader" id="2_qcvix"]
+
+[sub_resource type="ShaderMaterial" id="ShaderMaterial_85vqh"]
+resource_local_to_scene = true
+shader = ExtResource("2_qcvix")
+shader_parameter/flash_color = Color(1, 1, 1, 1)
+shader_parameter/progress = 0.0
 
 [sub_resource type="RectangleShape2D" id="RectangleShape2D_kt0x3"]
 
@@ -12,6 +19,7 @@ script = ExtResource("1_yqwu2")
 
 [node name="Sprite2D" type="Sprite2D" parent="."]
 texture_filter = 1
+material = SubResource("ShaderMaterial_85vqh")
 scale = Vector2(1.75, 1.75)
 texture = ExtResource("2_jkjfl")
 
@@ -21,4 +29,8 @@ texture = ExtResource("2_jkjfl")
 scale = Vector2(2.9641, 2.94208)
 shape = SubResource("RectangleShape2D_kt0x3")
 
+[node name="HitTimer" type="Timer" parent="."]
+wait_time = 0.2
+one_shot = true
+
 [connection signal="area_entered" from="Area2D" to="." method="_on_area_2d_area_entered"]

scripts/enemy.gd

@@ -1,21 +1,34 @@
 extends PathFollow2D
 
 @export var speed: float # gets set in main.gd, so we dont really need to initialize any value here
+@onready var sprite_reference = get_node("Sprite2D")
+@onready var hit_timer = get_node("HitTimer")
 
 var health = 2
+var damage = 5
 
 func _ready():
 	progress = 0
 
+func _process(delta):
+	sprite_reference.material.set_shader_parameter("progress", get_hit_timer_progress())
+
+func get_hit_timer_progress():
+	return hit_timer.time_left / hit_timer.wait_time
+
 func _physics_process(delta):
 	if progress_ratio < 1.0:
 		progress += speed * delta
 	else:
-		eventmanager.broadcast_player_take_damage(1)
+		eventmanager.broadcast_player_take_damage(get_damage())
 		queue_free()
+
+func get_damage():
+	return damage
 
 func _on_area_2d_area_entered(area):
 	if area.is_in_group("projectile"):
+		hit_timer.start()
 		health -= area.get_damage()
 		area.queue_free() # destroy the projectile
 		if health == 0:

shaders/hitflash.gdshader

@@ -0,0 +1,10 @@
+shader_type canvas_item;
+
+uniform vec4 flash_color : source_color;
+uniform float progress;
+
+void fragment() {
+	vec4 color = texture(TEXTURE, UV);
+	color.rgb = mix(color, flash_color, progress).rgb;
+	COLOR = color;
+}