niveau/transitions: shader de transition

Entre les niveaux et à la mort il y a maintenant un fondu au noir qui se
met en place pour éviter d'avoir la gerbe sur les mouvements de caméra.
la physique est en pause pendant la transition.

shaders/transition_shader.tscn

@@ -0,0 +1,90 @@
+[gd_scene load_steps=8 format=3 uid="uid://17macg0q4k8l"]
+
+[ext_resource type="Shader" path="res://shaders/transition_shader.gdshader" id="1_kyfmm"]
+[ext_resource type="Texture2D" uid="uid://b5mne7k2hxq4m" path="res://shaders/masks/curtain.png" id="2_pg1r4"]
+
+[sub_resource type="ShaderMaterial" id="ShaderMaterial_g48os"]
+shader = ExtResource("1_kyfmm")
+shader_parameter/cutoff = 0.0
+shader_parameter/smooth_size = 0.1
+shader_parameter/mask = ExtResource("2_pg1r4")
+
+[sub_resource type="GDScript" id="GDScript_rrd13"]
+script/source = "class_name FadeShader extends ColorRect
+
+signal fade_in_done()
+signal fade_out_done()
+
+@onready var player := $\"AnimationPlayer\" as AnimationPlayer
+
+func fade_in():
+    player.play(&\"fade_in\")
+
+func fade_out():
+    player.play(&\"fade_out\")
+
+func _on_animation_player_animation_finished(anim_name: StringName) -> void:
+    if anim_name == \"fade_in\":
+        fade_in_done.emit()
+    elif anim_name == \"fade_out\":
+        fade_out_done.emit()
+"
+
+[sub_resource type="Animation" id="Animation_yg4ht"]
+resource_name = "fade_in"
+length = 0.5
+tracks/0/type = "value"
+tracks/0/imported = false
+tracks/0/enabled = true
+tracks/0/path = NodePath(".:material:shader_parameter/cutoff")
+tracks/0/interp = 1
+tracks/0/loop_wrap = true
+tracks/0/keys = {
+"times": PackedFloat32Array(0.2, 0.4),
+"transitions": PackedFloat32Array(1, 0.450625),
+"update": 0,
+"values": [0.0, 1.0]
+}
+
+[sub_resource type="Animation" id="Animation_mavdc"]
+resource_name = "fade_out"
+length = 0.25
+tracks/0/type = "value"
+tracks/0/imported = false
+tracks/0/enabled = true
+tracks/0/path = NodePath(".:material:shader_parameter/cutoff")
+tracks/0/interp = 1
+tracks/0/loop_wrap = true
+tracks/0/keys = {
+"times": PackedFloat32Array(0, 0.2),
+"transitions": PackedFloat32Array(1, 1),
+"update": 0,
+"values": [1.0, 0.0]
+}
+
+[sub_resource type="AnimationLibrary" id="AnimationLibrary_kedvi"]
+_data = {
+"fade_in": SubResource("Animation_yg4ht"),
+"fade_out": SubResource("Animation_mavdc")
+}
+
+[node name="TransitionShader" type="ColorRect"]
+material = SubResource("ShaderMaterial_g48os")
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+offset_right = -1680.0
+offset_bottom = -945.0
+grow_horizontal = 2
+grow_vertical = 2
+size_flags_horizontal = 3
+size_flags_vertical = 3
+color = Color(0, 0, 0, 1)
+script = SubResource("GDScript_rrd13")
+
+[node name="AnimationPlayer" type="AnimationPlayer" parent="."]
+libraries = {
+"": SubResource("AnimationLibrary_kedvi")
+}
+
+[connection signal="animation_finished" from="AnimationPlayer" to="." method="_on_animation_player_animation_finished"]