Replace old book mesh with LOD system on warcraft scene

assets/props/book/sm_book.tscn

@@ -0,0 +1,119 @@
+[gd_scene load_steps=5 format=2]
+
+[ext_resource path="res://assets/props/book/sm_book_lod0.mesh" type="ArrayMesh" id=1]
+[ext_resource path="res://assets/props/book/sm_book_lod1.mesh" type="ArrayMesh" id=2]
+[ext_resource path="res://assets/props/book/sm_book_lod2.mesh" type="ArrayMesh" id=3]
+
+[sub_resource type="GDScript" id=1]
+script/source = "# Copyright © 2020 Hugo Locurcio and contributors - MIT License
+# See `LICENSE.md` included in the source distribution for details.
+extends Spatial
+class_name LODSpatial, \"res://addons/lod/lod_spatial.svg\"
+
+# If `false`, LOD won't update anymore. This can be used for performance comparison
+# purposes.
+export var enable_lod := true
+
+# The maximum LOD 0 (high quality) distance in units.
+export(float, 0.0, 1000.0, 0.1) var lod_0_max_distance := 10
+
+# The maximum LOD 1 (medium quality) distance in units.
+export(float, 0.0, 1000.0, 0.1) var lod_1_max_distance := 25
+
+# The maximum LOD 2 (low quality) distance in units.
+# Past this distance, all LOD variants are hidden.
+export(float, 0.0, 1000.0, 0.1) var lod_2_max_distance := 100
+
+# The rate at which LODs will be updated (in seconds). Lower values are more reactive
+# but use more CPU, which is especially noticeable with large amounts of LOD-enabled nodes.
+# Set this accordingly depending on your camera movement speed.
+# The default value should suit most projects already.
+# Note: Slow cameras don't need to have LOD-enabled objects update their status often.
+# This can overridden by setting the project setting `lod/refresh_rate`.
+var refresh_rate := 0.25
+
+# The LOD bias in units.
+# Positive values will decrease the detail level and improve performance.
+# Negative values will improve visual appearance at the cost of performance.
+# This can overridden by setting the project setting `lod/bias`.
+var lod_bias := 0.0
+
+# The internal refresh timer.
+var timer := 0.0
+
+
+func _ready() -> void:
+	if ProjectSettings.has_setting(\"lod/spatial_bias\"):
+		lod_bias = ProjectSettings.get_setting(\"lod/spatial_bias\")
+	if ProjectSettings.has_setting(\"lod/refresh_rate\"):
+		refresh_rate = ProjectSettings.get_setting(\"lod/refresh_rate\")
+
+	# Add random jitter to the timer to ensure LODs don't all swap at the same time.
+	randomize()
+	timer += rand_range(0, refresh_rate)
+
+
+# Despite LOD not being related to physics, we chose to run in `_physics_process()`
+# to minimize the amount of method calls per second (and therefore decrease CPU usage).
+func _physics_process(delta: float) -> void:
+	if not enable_lod:
+		return
+
+	# We need a camera to do the rest.
+	var camera := get_viewport().get_camera()
+	if camera == null:
+		return
+
+	if timer <= refresh_rate:
+		timer += delta
+		return
+
+	timer = 0.0
+
+	var distance := camera.global_transform.origin.distance_to(global_transform.origin) + lod_bias
+	# The LOD level to choose (lower is more detailed).
+	var lod: int
+	if distance < lod_0_max_distance:
+		lod = 0
+	elif distance < lod_1_max_distance:
+		lod = 1
+	elif distance < lod_2_max_distance:
+		lod = 2
+	else:
+		# Hide the LOD object entirely.
+		lod = 3
+
+	for node in get_children():
+		# `-lod` also matches `-lod0`, `-lod1`, `-lod2`, …
+		if node.has_method(\"set_visible\"):
+			if \"-lod0\" in node.name:
+				node.visible = lod == 0
+			if \"-lod1\" in node.name:
+				node.visible = lod == 1
+			if \"-lod2\" in node.name:
+				node.visible = lod == 2
+"
+
+[node name="sm_book" type="Spatial"]
+script = SubResource( 1 )
+lod_0_max_distance = 1.0
+lod_1_max_distance = 5.0
+lod_2_max_distance = 10.0
+
+[node name="sm_book-lod0" type="MeshInstance" parent="."]
+use_in_baked_light = true
+mesh = ExtResource( 1 )
+material/0 = null
+
+[node name="sm_book-lod1" type="MeshInstance" parent="."]
+transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0.00205189, 0, -0.0098635 )
+visible = false
+use_in_baked_light = true
+mesh = ExtResource( 2 )
+material/0 = null
+
+[node name="sm_book-lod2" type="MeshInstance" parent="."]
+visible = false
+use_in_baked_light = true
+mesh = ExtResource( 3 )
+material/0 = null