Load a room with expensive stuff in it on game start to precache things

levels/precache_room/precache_room.tscn

@@ -0,0 +1,31 @@
+[gd_scene load_steps=7 format=3 uid="uid://dtuwt3kemds6o"]
+
+[ext_resource type="Material" uid="uid://cqjr3cbxtfg2j" path="res://assets/materials/grunk_overlays/gunk_overlay.material" id="1_wo7bt"]
+[ext_resource type="Material" uid="uid://c1vy4bkwb1g5m" path="res://assets/materials/grunk_overlays/lowrez_overlay.material" id="2_oj27o"]
+[ext_resource type="Material" uid="uid://dutkfm4ek0ysh" path="res://assets/materials/grunk_overlays/bright_overlay.material" id="3_41thd"]
+[ext_resource type="PackedScene" uid="uid://2yqi5u5eo025" path="res://src/world/gunk_node/grunk_nodule.tscn" id="4_3phbs"]
+[ext_resource type="PackedScene" uid="uid://brrd33217oplv" path="res://src/world/grunk_beast/shambler/shambler.tscn" id="5_ynncq"]
+
+[sub_resource type="QuadMesh" id="QuadMesh_3qnro"]
+
+[node name="PrecacheRoom" type="Node3D"]
+
+[node name="MeshInstance3D" type="MeshInstance3D" parent="."]
+material_overlay = ExtResource("1_wo7bt")
+mesh = SubResource("QuadMesh_3qnro")
+
+[node name="MeshInstance3D2" type="MeshInstance3D" parent="."]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, -3)
+material_overlay = ExtResource("2_oj27o")
+mesh = SubResource("QuadMesh_3qnro")
+
+[node name="MeshInstance3D3" type="MeshInstance3D" parent="."]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, -6)
+material_overlay = ExtResource("3_41thd")
+mesh = SubResource("QuadMesh_3qnro")
+
+[node name="GrunkNodule" parent="." instance=ExtResource("4_3phbs")]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 3, 0, 0)
+
+[node name="Shambler" parent="." instance=ExtResource("5_ynncq")]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 3, 0, -3)

src/game/game.tscn

@@ -1,8 +1,9 @@
-[gd_scene load_steps=13 format=3 uid="uid://qpq2cm1hgeha"]
+[gd_scene load_steps=14 format=3 uid="uid://qpq2cm1hgeha"]
 
 [ext_resource type="Script" uid="uid://dxl25lkyped4" path="res://src/game/game.gd" id="1_qnjlk"]
 [ext_resource type="Theme" uid="uid://dj2ij1b2yjicr" path="res://src/ui/menus/title_screen/title_screen.theme" id="2_kgj8g"]
 [ext_resource type="Script" uid="uid://ctf1if4ly6nun" path="res://src/game/loading_screen.gd" id="3_kgj8g"]
+[ext_resource type="Script" uid="uid://byoyeyop7dlra" path="res://src/game/shader_precache.gd" id="31_yi3n0"]
 
 [sub_resource type="Animation" id="Animation_kgj8g"]
 length = 0.001
@@ -156,6 +157,22 @@ transitions = ["Start", "initial_display", SubResource("AnimationNodeStateMachin
 script = ExtResource("1_qnjlk")
 start_scene = "uid://bctwol681jdk0"
 
+[node name="ShaderPrecache" type="SubViewport" parent="."]
+render_target_update_mode = 4
+script = ExtResource("31_yi3n0")
+precache_scene_path = "uid://dtuwt3kemds6o"
+
+[node name="CanvasLayer" type="CanvasLayer" parent="ShaderPrecache"]
+layer = -1
+visible = false
+
+[node name="PrecacheRoot" type="Node3D" parent="ShaderPrecache/CanvasLayer"]
+unique_name_in_owner = true
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, -1000, 0)
+
+[node name="Camera3D" type="Camera3D" parent="ShaderPrecache/CanvasLayer/PrecacheRoot"]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1.65382)
+
 [node name="Content" type="Node" parent="."]
 unique_name_in_owner = true
 

src/game/shader_precache.gd

@@ -0,0 +1,39 @@
+extends SubViewport
+## Render a set of shader materials for one frame to force a cache
+
+@export_file("*.tscn") var precache_scene_path: String
+
+var _precache_started := false
+var _scene_loaded := false
+var _scene_rendered := false
+
+@onready var precache_root: Node3D = %PrecacheRoot
+
+
+# Called every frame. 'delta' is the elapsed time since the previous frame.
+func _process(_delta: float) -> void:
+	if not _precache_started:
+		print_debug("Loading precache scene...")
+		Game.instance.queue_load(precache_scene_path, ResourceLoader.CACHE_MODE_REUSE).finally(
+			_on_precache_scene_loaded
+		)
+		_precache_started = true
+		return
+
+	if not _scene_loaded:
+		return
+
+	if not _scene_rendered:
+		print_debug("Rendering precache scene...")
+		_scene_rendered = true
+		return
+
+	print_debug("Shader precache complete!")
+	queue_free()
+
+
+func _on_precache_scene_loaded(scene: PackedScene) -> void:
+	print_debug("Precache scene loaded. Now instantiating...")
+	var instance: Node3D = scene.instantiate()
+	precache_root.add_child(instance)
+	_scene_loaded = true

src/game/shader_precache.gd.uid

@@ -0,0 +1 @@
+uid://byoyeyop7dlra

src/world/grunk_beast/shambler/shambler.tscn

@@ -331,7 +331,7 @@ primary_limit_angle = 1.5708
 primary_damp_threshold = 0.4
 
 [node name="SleeveL" type="BoneAttachment3D" parent="Armature/Skeleton3D" index="2"]
-transform = Transform3D(0.0438309, 7.45058e-08, -0.999039, -0.998162, -0.0418897, -0.0437925, -0.0418494, 0.999122, -0.0018359, 0.214328, -0.075648, -0.79725)
+transform = Transform3D(0.0438309, 7.45058e-08, -0.999039, 0.999039, 6.10948e-07, 0.0438309, 7.37607e-07, -1, -4.47035e-08, 1.63061, 0.0124229, 0.803842)
 bone_name = "Sleeve.L"
 bone_idx = 27
 
@@ -342,7 +342,7 @@ particle_scene = ExtResource("5_lqi3b")
 metadata/_custom_type_script = "uid://cuqr167olan8n"
 
 [node name="SleeveR" type="BoneAttachment3D" parent="Armature/Skeleton3D" index="3"]
-transform = Transform3D(0.0438309, -7.45058e-08, 0.999039, 0.998162, -0.0418897, -0.0437925, 0.0418494, 0.999122, -0.0018359, -0.214327, -0.0756485, -0.79725)
+transform = Transform3D(0.0438309, -7.45058e-08, 0.999039, -0.999039, 6.10948e-07, 0.0438309, -7.37607e-07, -1, -4.47035e-08, -1.63061, 0.0124234, 0.803842)
 bone_name = "Sleeve.R"
 bone_idx = 31
 
@@ -425,6 +425,7 @@ process_material = SubResource("ParticleProcessMaterial_xyfav")
 draw_pass_1 = SubResource("SphereMesh_o6myl")
 
 [node name="GurglePop" type="GPUParticles3D" parent="SpawnEffects/GurgleEffect" index="0"]
+emitting = false
 amount = 64
 lifetime = 0.2
 preprocess = 1.13