screen filters system?

assets/screen_filters/lcd.tres

@@ -0,0 +1,11 @@
+[gd_resource type="ShaderMaterial" load_steps=2 format=3 uid="uid://sppw51urwmf3"]
+
+[ext_resource type="Shader" uid="uid://bgy86nka8c76n" path="res://assets/shaders/lcd.gdshader" id="1_y1c64"]
+
+[resource]
+shader = ExtResource("1_y1c64")
+shader_parameter/enabled = true
+shader_parameter/resolution = Vector2(256, 192)
+shader_parameter/curvature = Vector2(1, 1)
+shader_parameter/scanline_opacity = Vector2(0.1, 0.1)
+shader_parameter/brightness = 1.0

assets/shaders/lcd.gdshader

@@ -0,0 +1,43 @@
+shader_type canvas_item;
+
+uniform sampler2D SCREEN_TEXTURE : hint_screen_texture, filter_linear_mipmap;
+
+uniform bool enabled = true;
+uniform vec2 resolution;
+uniform vec2 curvature;
+uniform vec2 scanline_opacity;
+uniform float brightness;
+
+vec2 curve_uv(vec2 uv) {
+    uv = uv * 2.0 - 1.0;
+    vec2 offset = abs(uv.yx) / vec2(curvature.x, curvature.y);
+    uv = uv + uv * offset * offset;
+    uv = uv * 0.5 + 0.5;
+    return uv;
+}
+
+vec3 scanline_intensity(float uv, float res, float opacity) {
+    float intensity = sin((uv * res - 0.25) * PI * 2.0);
+    intensity = ((0.5 * intensity) + 0.5) * 0.9 + 0.1;
+    return vec3(pow(intensity, opacity));
+}
+
+void fragment() {
+	if (enabled) {
+	vec2 curved_uv = SCREEN_UV;
+	vec3 base_color = texture(SCREEN_TEXTURE, curved_uv).rgb;
+	
+	base_color += vec3(1.0/256.0);
+	base_color *= scanline_intensity(curved_uv.x, resolution.x, scanline_opacity.y);
+	base_color *= scanline_intensity(curved_uv.y, resolution.y, scanline_opacity.x);
+	base_color *= vec3(brightness);
+	
+	if (curved_uv.x < 0.0 || curved_uv.y < 0.0 || curved_uv.x > 1.0 || curved_uv.y > 1.0) {
+        COLOR = vec4(0.0, 0.0, 0.0, 0.0);
+    } else {
+        COLOR = vec4(base_color, 1.0);
+    }
+	} else {
+		COLOR = texture(SCREEN_TEXTURE, SCREEN_UV);
+	}
+}

assets/shaders/lcd.gdshader.uid

@@ -0,0 +1 @@
+uid://bgy86nka8c76n

autoloads/display.gd

@@ -18,9 +18,13 @@ enum ScaleMode {
 		if is_node_ready():
 			_update_scale()
 
+## Directory to scan screen filters from.
+@export_dir var filters_dir: String = "res://"
+
 @export_group("Internal References")
 @export var _viewport: SubViewport
 @export var _viewport_container: SubViewportContainer
+@export var _native_filters_layer: CanvasLayer
 
 
 ## The native resolution of the game.
@@ -29,11 +33,37 @@ var size: Vector2i = Vector2i(
 	ProjectSettings.get_setting("display/window/size/viewport_height"),
 )
 
+## Whether each filter is enabled or disabled.
+var filters_enabled: Dictionary[StringName, bool] = {}
+
+
+var _filter_instances: Dictionary[StringName, ColorRect] = {}
+
 
 func _enter_tree() -> void:
 	get_tree().scene_changed.connect(_on_scene_changed)
 	get_tree().root.size_changed.connect(_update_scale)
 	
+	# populate screen filters
+	for file in ResourceLoader.list_directory(filters_dir):
+		var material = load(filters_dir.path_join(file)) as Material
+		if material:
+			var id = StringName(file.get_basename())
+			
+			if _filter_instances.has(id):
+				push_error("Screen filter %s exists in two different resource files. Only one will exist" % id)
+				_filter_instances[id].queue_free()
+				_filter_instances.erase(id)
+			
+			var instance = ColorRect.new()
+			instance.material = material
+			if material.get_meta(&"filter_native_resolution", false):
+				_native_filters_layer.add_child(instance)
+			else:
+				_viewport_container.add_child(instance)
+			_filter_instances[id] = instance
+			filters_enabled[id] = true
+	
 	_update_scale.call_deferred()
 	
 	var current_scene = get_tree().current_scene
@@ -69,3 +99,8 @@ func _update_scale() -> void:
 		ScaleMode.STRETCH:
 			# just use the ratio as-is
 			_viewport_container.scale = size_ratio
+	
+	# update screen filters state
+	for filter in filters_enabled:
+		_filter_instances[filter].visible = filters_enabled[filter]
+		_filter_instances[filter].custom_minimum_size = Vector2(size)

autoloads/display.tscn

@@ -2,11 +2,12 @@
 
 [ext_resource type="Script" uid="uid://kwa8v1dhwlie" path="res://autoloads/display.gd" id="1_1seuv"]
 
-[node name="Display" type="Node" node_paths=PackedStringArray("_viewport", "_viewport_container")]
+[node name="Display" type="Node" node_paths=PackedStringArray("_viewport", "_viewport_container", "_native_filters_layer")]
 script = ExtResource("1_1seuv")
-scale_mode = 1
+filters_dir = "res://assets/screen_filters"
 _viewport = NodePath("SubViewportContainer/SubViewport")
 _viewport_container = NodePath("SubViewportContainer")
+_native_filters_layer = NodePath("SubViewportContainer/SubViewport/NativeResolutionFilters")
 
 [node name="SubViewportContainer" type="SubViewportContainer" parent="."]
 anchors_preset = 8
@@ -26,3 +27,6 @@ pivot_offset = Vector2(128, 96)
 handle_input_locally = false
 size = Vector2i(256, 192)
 render_target_update_mode = 4
+
+[node name="NativeResolutionFilters" type="CanvasLayer" parent="SubViewportContainer/SubViewport"]
+layer = 2147483647

project.godot

@@ -11,6 +11,7 @@ config_version=5
 [application]
 
 config/name="Luna Lunatic"
+run/main_scene="uid://bnjujh22nqr4a"
 config/features=PackedStringArray("4.5", "GL Compatibility")
 config/icon="res://icon.svg"
 
@@ -26,6 +27,7 @@ window/size/viewport_height=192
 [file_customization]
 
 folder_colors={
+"res://assets/": "yellow",
 "res://autoloads/": "orange"
 }