Add an occlusion culling and mesh LOD demo (#801)

3d/occlusion_culling_mesh_lod/README.md

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+# Occlusion Culling and Mesh LOD
+
+This demo showcases the use of occlusion culling and mesh level of detail in a 3D scene.
+
+The demo contains 1,024 identical rooms in a 64×64 grid. The room geometry is
+used as a basis for a baked OccluderInstance3D, which allows each room to be
+culled if it is hidden by another room's walls.
+
+Occlusion culling can provide a performance benefit in draw call-bound
+scenarios. However, since the Forward Plus backend uses a depth prepass, the
+shading cost is already reduced by the depth prepass. As a result, occlusion
+culling will not always result in a tangible performance increase, especially in
+outdoor scenes that have fewer occlusion culling opportunities. Indoor scenes
+with no DirectionalLight3D casting shadows are a best-case scenario for
+occlusion culling.
+
+The blue spheres make use of automatically generated LODs, which reduce the
+number of triangles that need to be rendered each frame by the GPU. This
+provides a significant performance increase in scenes with complex geometry. In
+most scenes, this provides a greater performance benefit compared to occlusion
+culling.
+
+While running the demo, you can toggle the use of mesh LOD and occlusion culling
+to view the performance difference these features make in this project. Results
+will vary depending on your CPU and GPU model.
+
+> **Warning**
+>
+> If you are using a engine build that is not fully optimized, you may notice
+> that enabling occlusion culling decreases performance. This is because
+> occlusion culling is a demanding process on the CPU, which needs all the
+> build-time optimization it can get.
+>
+> Official builds are fully optimized, but self-compiled builds are not fully
+> optimized by default (use the `optimize=speed use_lto=yes` SCons options).
+
+Language: GDScript
+
+Renderer: Forward Plus
+
+## Screenshot
+
+![Screenshot](screenshots/occlusion_culling_mesh_lod.webp)

3d/occlusion_culling_mesh_lod/camera.gd

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+extends Camera3D
+
+const MOUSE_SENSITIVITY = 0.002
+const MOVE_SPEED = 1.5
+
+var rot = Vector3()
+var velocity = Vector3()
+
+
+func _ready():
+	Input.set_mouse_mode(Input.MOUSE_MODE_CAPTURED)
+
+
+func _input(event):
+	# Mouse look (only if the mouse is captured).
+	if event is InputEventMouseMotion and Input.get_mouse_mode() == Input.MOUSE_MODE_CAPTURED:
+		# Horizontal mouse look.
+		rot.y -= event.relative.x * MOUSE_SENSITIVITY
+		# Vertical mouse look.
+		rot.x = clamp(rot.x - event.relative.y * MOUSE_SENSITIVITY, -1.57, 1.57)
+		transform.basis = Basis.from_euler(rot)
+
+	if event.is_action_pressed("toggle_mouse_capture"):
+		if Input.get_mouse_mode() == Input.MOUSE_MODE_CAPTURED:
+			Input.set_mouse_mode(Input.MOUSE_MODE_VISIBLE)
+		else:
+			Input.set_mouse_mode(Input.MOUSE_MODE_CAPTURED)
+
+
+func _process(delta):
+	var motion = Vector3(
+			Input.get_axis(&"move_left", &"move_right"),
+			0,
+			Input.get_axis(&"move_forward", &"move_back")
+	)
+
+	# Normalize motion to prevent diagonal movement from being
+	# `sqrt(2)` times faster than straight movement.
+	motion = motion.normalized()
+
+	velocity += MOVE_SPEED * delta * (transform.basis * motion)
+	velocity *= 0.85
+	position += velocity

3d/occlusion_culling_mesh_lod/icon.png.import

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+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://d1a87sh6t6ncl"
+path="res://.godot/imported/icon.png-487276ed1e3a0c39cad0279d744ee560.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://icon.png"
+dest_files=["res://.godot/imported/icon.png-487276ed1e3a0c39cad0279d744ee560.ctex"]
+
+[params]
+
+compress/mode=0
+compress/lossy_quality=0.7
+compress/hdr_compression=1
+compress/bptc_ldr=0
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1

3d/occlusion_culling_mesh_lod/node_3d.gd

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+extends Node3D
+
+
+func _input(event):
+	if event.is_action_pressed("toggle_occlusion_culling"):
+		get_viewport().use_occlusion_culling = not get_viewport().use_occlusion_culling
+		update_labels()
+	if event.is_action_pressed("toggle_mesh_lod"):
+		get_viewport().mesh_lod_threshold = 1.0 if is_zero_approx(get_viewport().mesh_lod_threshold) else 0.0
+		update_labels()
+	if event.is_action_pressed("cycle_draw_mode"):
+		get_viewport().debug_draw = wrapi(get_viewport().debug_draw + 1, 0, 5)
+		update_labels()
+
+
+func _process(delta):
+	$Performance.text = """%d FPS (%.2f mspf)
+
+Currently rendering:
+%d objects
+%dK primitive indices
+%d draw calls
+""" % [
+	Engine.get_frames_per_second(),
+	1000.0 / Engine.get_frames_per_second(),
+	RenderingServer.get_rendering_info(RenderingServer.RENDERING_INFO_TOTAL_OBJECTS_IN_FRAME),
+	RenderingServer.get_rendering_info(RenderingServer.RENDERING_INFO_TOTAL_PRIMITIVES_IN_FRAME) * 0.001,
+	RenderingServer.get_rendering_info(RenderingServer.RENDERING_INFO_TOTAL_DRAW_CALLS_IN_FRAME),
+]
+
+
+func update_labels():
+	$OcclusionCulling.text = "Occlusion culling: %s" % ("Enabled" if get_viewport().use_occlusion_culling else "Disabled")
+	$MeshLOD.text = "Mesh LOD: %s" % ("Enabled" if not is_zero_approx(get_viewport().mesh_lod_threshold) else "Disabled")
+	$DrawMode.text = "Draw mode: %s" % get_draw_mode_string(get_viewport().debug_draw)
+
+
+func get_draw_mode_string(draw_mode):
+	match draw_mode:
+		0:
+			return "Normal"
+		1:
+			return "Unshaded"
+		2:
+			return "Lighting"
+		3:
+			return "Overdraw"
+		4:
+			return "Wireframe"

3d/occlusion_culling_mesh_lod/project.godot

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+; Engine configuration file.
+; It's best edited using the editor UI and not directly,
+; since the parameters that go here are not all obvious.
+;
+; Format:
+;   [section] ; section goes between []
+;   param=value ; assign values to parameters
+
+config_version=5
+
+[application]
+
+config/name="Occlusion Culling and Mesh LOD"
+config/description="This demo showcases the use of occlusion culling and mesh level of detail in a 3D scene."
+run/main_scene="res://node_3d.tscn"
+config/features=PackedStringArray("4.0")
+config/icon="res://icon.png"
+
+[display]
+
+window/vsync/vsync_mode=0
+window/stretch/mode="canvas_items"
+window/stretch/aspect="expand"
+
+[filesystem]
+
+import/blender/enabled=false
+
+[input]
+
+move_forward={
+"deadzone": 0.5,
+"events": [Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":87,"unicode":0,"echo":false,"script":null)
+, Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":4194320,"unicode":0,"echo":false,"script":null)
+]
+}
+move_back={
+"deadzone": 0.5,
+"events": [Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":83,"unicode":0,"echo":false,"script":null)
+, Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":4194322,"unicode":0,"echo":false,"script":null)
+]
+}
+move_right={
+"deadzone": 0.5,
+"events": [Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":68,"unicode":0,"echo":false,"script":null)
+, Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":4194321,"unicode":0,"echo":false,"script":null)
+]
+}
+move_left={
+"deadzone": 0.5,
+"events": [Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":65,"unicode":0,"echo":false,"script":null)
+, Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":4194319,"unicode":0,"echo":false,"script":null)
+]
+}
+toggle_occlusion_culling={
+"deadzone": 0.5,
+"events": [Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":79,"physical_keycode":0,"unicode":0,"echo":false,"script":null)
+]
+}
+toggle_mesh_lod={
+"deadzone": 0.5,
+"events": [Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":76,"physical_keycode":0,"unicode":0,"echo":false,"script":null)
+]
+}
+cycle_draw_mode={
+"deadzone": 0.5,
+"events": [Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":32,"unicode":0,"echo":false,"script":null)
+]
+}
+toggle_mouse_capture={
+"deadzone": 0.5,
+"events": [Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":4194305,"unicode":0,"echo":false,"script":null)
+, Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":4194341,"unicode":0,"echo":false,"script":null)
+]
+}
+
+[rendering]
+
+anti_aliasing/quality/screen_space_aa=1
+anti_aliasing/quality/use_debanding=true
+occlusion_culling/use_occlusion_culling=true

3d/occlusion_culling_mesh_lod/room.blend.import

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+[remap]
+
+importer="scene"
+importer_version=1
+type="PackedScene"
+uid="uid://cynp2w1tdntud"
+path="res://.godot/imported/room.blend-36213b70cb5ffa4e1f840d45a32b9acb.scn"
+
+[deps]
+
+source_file="res://room.blend"
+dest_files=["res://.godot/imported/room.blend-36213b70cb5ffa4e1f840d45a32b9acb.scn"]
+
+[params]
+
+nodes/root_type="Node3D"
+nodes/root_name="Scene Root"
+nodes/apply_root_scale=true
+nodes/root_scale=1.0
+meshes/ensure_tangents=true
+meshes/generate_lods=true
+meshes/create_shadow_meshes=true
+meshes/light_baking=1
+meshes/lightmap_texel_size=0.2
+skins/use_named_skins=true
+animation/import=true
+animation/fps=30
+import_script/path=""
+_subresources={}
+blender/nodes/visible=2
+blender/nodes/punctual_lights=true
+blender/nodes/cameras=true
+blender/nodes/custom_properties=true
+blender/nodes/modifiers=1
+blender/meshes/colors=false
+blender/meshes/uvs=true
+blender/meshes/normals=true
+blender/meshes/tangents=true
+blender/meshes/skins=2
+blender/meshes/export_bones_deforming_mesh_only=false
+blender/materials/unpack_enabled=true
+blender/materials/export_materials=1
+blender/animation/limit_playback=true
+blender/animation/always_sample=true
+blender/animation/group_tracks=true

3d/occlusion_culling_mesh_lod/room.glb.import

@@ -0,0 +1,29 @@
+[remap]
+
+importer="scene"
+importer_version=1
+type="PackedScene"
+uid="uid://ck4wa4vxhhk1v"
+path="res://.godot/imported/room.glb-80432416ed16d717e78c80d413b8774e.scn"
+
+[deps]
+
+source_file="res://room.glb"
+dest_files=["res://.godot/imported/room.glb-80432416ed16d717e78c80d413b8774e.scn"]
+
+[params]
+
+nodes/root_type="Node3D"
+nodes/root_name="Scene Root"
+nodes/apply_root_scale=true
+nodes/root_scale=1.0
+meshes/ensure_tangents=true
+meshes/generate_lods=true
+meshes/create_shadow_meshes=true
+meshes/light_baking=1
+meshes/lightmap_texel_size=0.2
+skins/use_named_skins=true
+animation/import=true
+animation/fps=30
+import_script/path=""
+_subresources={}