TransitionManager effect

addons/great_games_library/static/ThreadUtility/ThreadUtility.gd

@@ -1,7 +1,7 @@
 class_name ThreadUtility
 extends Node
 
-## Load next scene from path using a thread
+## Load a resource from path using a thread
 static func load_resource(path:String, receive_callback:Callable)->void:
 	# create thread function to load resource and shut down the tread
 	var _tread_load:Callable = func (path:String, callback:Callable, thread:Thread)->PackedScene:

addons/top_down/resources/materials/transition.gdshader

@@ -0,0 +1,26 @@
+shader_type canvas_item;
+// https://godotshaders.com/shader/pixel-melt/
+
+// Animate from 0 to 1
+uniform float progress: hint_range(0.0, 1.0) = 0.0;
+
+// How jagged each band of melting pixels are
+uniform float meltiness: hint_range(0.0, 16.0) = 1.0;
+
+float psuedo_rand(float x) {
+	return mod(x * 2048103.0 + cos(x * 1912.0), 1.0);
+}
+
+void fragment() {
+	vec2 uv = UV;
+
+	// Move pixels near the top faster
+	uv.y -= progress / UV.y;
+
+	// Created jagged edges for each pixel on the x-axis
+	uv.y -= progress * meltiness * psuedo_rand(UV.x - mod(UV.x, TEXTURE_PIXEL_SIZE.x));
+
+	COLOR = texture(TEXTURE, uv);
+
+	COLOR.a = step(0.0, uv.y);
+}

addons/top_down/resources/materials/transition_material.tres

@@ -0,0 +1,8 @@
+[gd_resource type="ShaderMaterial" load_steps=2 format=3 uid="uid://dfinp0iie47mi"]
+
+[ext_resource type="Shader" path="res://addons/top_down/resources/materials/transition.gdshader" id="1_p1h5q"]
+
+[resource]
+shader = ExtResource("1_p1h5q")
+shader_parameter/progress = 0.0
+shader_parameter/meltiness = 1.0

addons/top_down/scenes/autoloads/transition.tscn

@@ -0,0 +1,56 @@
+[gd_scene load_steps=6 format=3 uid="uid://bxj12cduwftxm"]
+
+[ext_resource type="Script" path="res://addons/top_down/scripts/game/TransitionManager.gd" id="1_b8a2a"]
+[ext_resource type="Material" uid="uid://dfinp0iie47mi" path="res://addons/top_down/resources/materials/transition_material.tres" id="2_ha7dd"]
+
+[sub_resource type="Animation" id="Animation_g4wgy"]
+resource_name = "transition"
+length = 0.5
+tracks/0/type = "value"
+tracks/0/imported = false
+tracks/0/enabled = true
+tracks/0/path = NodePath("TextureRect:material:shader_parameter/progress")
+tracks/0/interp = 1
+tracks/0/loop_wrap = true
+tracks/0/keys = {
+"times": PackedFloat32Array(0, 0.5),
+"transitions": PackedFloat32Array(2, 1),
+"update": 0,
+"values": [0.0, 1.0]
+}
+
+[sub_resource type="Animation" id="Animation_y5efb"]
+length = 0.001
+tracks/0/type = "value"
+tracks/0/imported = false
+tracks/0/enabled = true
+tracks/0/path = NodePath("TextureRect:material:shader_parameter/progress")
+tracks/0/interp = 1
+tracks/0/loop_wrap = true
+tracks/0/keys = {
+"times": PackedFloat32Array(0),
+"transitions": PackedFloat32Array(1),
+"update": 0,
+"values": [0.0]
+}
+
+[sub_resource type="AnimationLibrary" id="AnimationLibrary_vk8ru"]
+_data = {
+"RESET": SubResource("Animation_y5efb"),
+"transition": SubResource("Animation_g4wgy")
+}
+
+[node name="Transition" type="CanvasLayer" node_paths=PackedStringArray("texture_rect")]
+layer = 5
+script = ExtResource("1_b8a2a")
+texture_rect = NodePath("TextureRect")
+
+[node name="TextureRect" type="TextureRect" parent="."]
+material = ExtResource("2_ha7dd")
+offset_right = 40.0
+offset_bottom = 40.0
+
+[node name="AnimationPlayer" type="AnimationPlayer" parent="."]
+libraries = {
+"": SubResource("AnimationLibrary_vk8ru")
+}

addons/top_down/scripts/game/PlayerSpawner.gd

@@ -32,5 +32,7 @@ func on_player_scene_entry()->void:
 
 func on_scene_transition()->void:
 	player_instance_resource.parent_reference_resource.node.remove_child(player_reference.node)
+
 	#get_tree().change_scene_to_file(scene_transition_resource.next_scene_path)
-	ThreadUtility.load_resource(scene_transition_resource.next_scene_path, get_tree().change_scene_to_packed)
+	#ThreadUtility.load_resource(scene_transition_resource.next_scene_path, get_tree().change_scene_to_packed)
+	Transition.change_scene(scene_transition_resource.next_scene_path)

addons/top_down/scripts/game/TransitionManager.gd

@@ -0,0 +1,42 @@
+class_name TransitionManager
+extends CanvasLayer
+
+@export var texture_rect:TextureRect
+@export var transition_time:float = 1.0
+
+var game_resolution:Vector2i
+var tween:Tween
+
+func _ready()->void:
+	visible = false
+	game_resolution = get_viewport().content_scale_size
+
+func change_scene(path:String)->void:
+	# wait for rendering everything on a screen
+	await RenderingServer.frame_post_draw
+
+	# get texture from the screen
+	var _image:Image = get_viewport().get_texture().get_image()
+	_image.resize(game_resolution.x, game_resolution.y, Image.INTERPOLATE_NEAREST)
+	var _image_texture:ImageTexture = ImageTexture.create_from_image(_image)
+	texture_rect.texture = _image_texture
+
+	get_tree().current_scene.visible = false
+	visible = true
+	transition_progress(0.0)
+
+	ThreadUtility.load_resource(path, scene_loaded)
+
+## Set transition in motion
+func scene_loaded(scene:PackedScene)->void:
+	assert(scene != null)
+	get_tree().change_scene_to_packed(scene)
+
+	if tween != null:
+		tween.kill()
+	tween = create_tween()
+	tween.tween_method(transition_progress, 0.0, 1.0, transition_time).set_ease(Tween.EASE_IN).set_trans(Tween.TRANS_CUBIC)
+	tween.finished.connect(set_visible.bind(false))
+
+func transition_progress(t:float)->void:
+	(texture_rect.material as ShaderMaterial).set_shader_parameter("progress", t)

addons/top_down/scripts/ui/title_screen/ChangeSceneButton.gd

@@ -11,5 +11,7 @@ func pressed()->void:
 	# Avoid triggering multiple times
 	# Deffered because this function is called by that signal
 	button.pressed.disconnect.call_deferred(pressed)
+
 	#get_tree().change_scene_to_file(scene_path)
-	ThreadUtility.load_resource(scene_path, get_tree().change_scene_to_packed)
+	#ThreadUtility.load_resource(scene_path, get_tree().change_scene_to_packed)
+	Transition.change_scene(scene_path)

project.godot

@@ -20,6 +20,7 @@ config/icon="res://icon.svg"
 SoundManager="*res://addons/top_down/scenes/autoloads/sound_manager.tscn"
 Music="*res://addons/top_down/scenes/autoloads/music.tscn"
 LoadManager="*res://addons/great_games_library/nodes/LoadManager/LoadManager.gd"
+Transition="*res://addons/top_down/scenes/autoloads/transition.tscn"
 
 [display]