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3D Lighting
Expert guidance for realistic 3D lighting with shadows and global illumination.
NEVER Do
- NEVER use VoxelGI without setting a proper extents — Unbound VoxelGI tanks performance. Always set
size to tightly fit your scene.
- NEVER enable shadows on every light — Each shadow-casting light is expensive. Use shadows sparingly: 1-2 DirectionalLights, ~3-5 OmniLights max.
- NEVER forget directional_shadow_mode — Default is ORTHOGONAL. For large outdoor scenes, use PARALLEL_4_SPLITS for better shadow quality at distance.
- NEVER use LightmapGI for fully dynamic scenes — Lightmaps are baked. Moving geometry won't receive updated lighting. Use VoxelGI or SDFGI instead.
- NEVER set omni_range too large — Light attenuation is quadratic. A range of 500 affects 785,000 sq units. Keep range as small as visually acceptable.
- NEVER hide a Light node using the Visible property to exclude it from a Lightmap bake — Hiding a light has no effect on the baker. You must change the light's Bake Mode to Disabled.
- NEVER use VoxelGI with paper-thin walls — VoxelGI evaluates lighting using a 3D grid. Thin walls (less than one voxel thick) will cause severe light leaking. Seal your geometry or place hidden thick MeshInstance3D blocks around the exterior.
- NEVER leave shadow bias at default for cascades — Default bias often causes Peter Panning or light leaking at split transitions. Tune bias per-light based on your scene's scale.
- NEVER bake LightmapGI without a Denoiser — Godot's baked lightmaps are noisy by default. Use OIDN or JNLM (in Project Settings) for professional results.
- NEVER use real-time SDFGI on Mobile/Compatibility renderers — It is a Forward+ exclusive feature. Use fake GI bounce lights for lower-end platforms.
- NEVER use 'Update Continuity' in ReflectionProbes for performance — Keep ReflectionProbes on 'Update Once' and trigger manual updates only when necessary.
Available Scripts
MANDATORY : Read the appropriate script before implementing the corresponding pattern.
Dynamic sun position and color based on time-of-day. Handles DirectionalLight3D rotation, color temperature, and intensity curves. Use for outdoor day/night systems.
VoxelGI and SDFGI management for global illumination setup.
Dynamic light pooling and LOD. Manages light culling and shadow toggling based on camera distance. Use for performance optimization with many lights.
Volumetric fog and god ray configuration. Runtime fog density/color adjustments and light shaft setup. Use for atmospheric effects.
Expert logic for adjusting DirectionalLight3D shadow split distances dynamically based on sun angle and camera tilt.
Advanced LightmapGI configuration pattern using Shadowmasking mode for hybrid static/dynamic shadowing.
Dynamic quality scaler for real-time Global Illumination (SDFGI). Adjusts cell size and occlusion for performance/quality trade-offs.
Smoothly transitioning localized fog density for cave entrances or forest clearings using Tweens and Area3D triggers.
Efficient 'Mobile-GI' pattern. Simulates light bouncing off the floor using non-shadowed directional fill lights.
Architectural pattern for transitioning WorldEnvironment parameters (Sky, Ambient, Tonemap) during gameplay.
Optimization script for correcting 'Peter Panning' and 'Shadow Acne' on high-fidelity directional lights.
Distance-based shadow and visibility culling for OmniLight3D nodes in dense environments.
Performance-aware ReflectionProbe handling using manual 'Update Once' triggers for large environmental changes.
High-detail lighting using Projector textures to fake complex shadow patterns (grates, glass ripples).
DirectionalLight3D (Sun/Moon)
Shadow Cascades
# For outdoor scenes with camera moving from near to far
extends DirectionalLight3D
func _ready() -> void:
shadow_enabled = true
directional_shadow_mode = SHADOW_PARALLEL_4_SPLITS
# Split distances (in meters from camera)
directional_shadow_split_1 = 10.0 # First cascade: 0-10m
directional_shadow_split_2 = 50.0 # Second: 10-50m
directional_shadow_split_3 = 200.0 # Third: 50-200m
# Fourth cascade: 200m - max shadow distance
directional_shadow_max_distance = 500.0
# Quality vs performance
directional_shadow_blend_splits = true # Smooth transitions
Day/Night Cycle
# sun_controller.gd
extends DirectionalLight3D
@export var time_of_day := 12.0 # 0-24 hours
@export var rotation_speed := 0.1 # Hours per second
func _process(delta: float) -> void:
time_of_day += rotation_speed * delta
if time_of_day >= 24.0:
time_of_day -= 24.0
# Rotate sun (0° = noon, 180° = midnight)
var angle := (time_of_day - 12.0) * 15.0 # 15° per hour
rotation_degrees.x = -angle
# Adjust intensity
if time_of_day < 6.0 or time_of_day > 18.0:
light_energy = 0.0 # Night
elif time_of_day < 7.0:
light_energy = remap(time_of_day, 6.0, 7.0, 0.0, 1.0) # Sunrise
elif time_of_day > 17.0:
light_energy = remap(time_of_day, 17.0, 18.0, 1.0, 0.0) # Sunset
else:
light_energy = 1.0 # Day
# Color shift
if time_of_day < 8.0 or time_of_day > 16.0:
light_color = Color(1.0, 0.7, 0.4) # Orange (dawn/dusk)
else:
light_color = Color(1.0, 1.0, 0.9) # Neutral white
OmniLight3D (Point Light)
Attenuation Tuning
# torch.gd
extends OmniLight3D
func _ready() -> void:
omni_range = 10.0 # Maximum reach
omni_attenuation = 2.0 # Falloff curve (1.0 = linear, 2.0 = quadratic/realistic)
# For "magical" lights, reduce attenuation
omni_attenuation = 0.5 # Flatter falloff, reaches farther
Flickering Effect
# campfire.gd
extends OmniLight3D
@export var base_energy := 1.0
@export var flicker_strength := 0.3
@export var flicker_speed := 5.0
func _process(delta: float) -> void:
var flicker := sin(Time.get_ticks_msec() * 0.001 * flicker_speed) * flicker_strength
light_energy = base_energy + flicker
SpotLight3D (Flashlight/Headlights)
Setup
# flashlight.gd
extends SpotLight3D
func _ready() -> void:
spot_range = 20.0
spot_angle = 45.0 # Cone angle (degrees)
spot_angle_attenuation = 2.0 # Edge softness
shadow_enabled = true
# Projector texture (optional - cookie/gobo)
light_projector = load("res://textures/flashlight_mask.png")
Follow Camera
# player_flashlight.gd
extends SpotLight3D
@onready var camera: Camera3D = get_viewport().get_camera_3d()
func _process(delta: float) -> void:
if camera:
global_transform = camera.global_transform
Global Illumination: VoxelGI vs SDFGI
Decision Matrix
| Feature | VoxelGI | SDFGI |
|---|
| Setup | Manual bounds per room | Automatic, scene-wide |
| Dynamic objects | Fully supported | Partially supported |
| Performance | Moderate | Higher cost |
| Use case | Indoor, small-medium scenes | Large outdoor scenes |
| Godot version | 4.0+ | 4.0+ |
VoxelGI Setup
# room_gi.gd - Place one VoxelGI per room/area
extends VoxelGI
func _ready() -> void:
# Tightly fit the room
size = Vector3(20, 10, 20)
# Quality settings
subdiv = VoxelGI.SUBDIV_128 # Higher = better quality, slower
# Bake GI data
bake()
SDFGI Setup
# world_environment.gd
extends WorldEnvironment
func _ready() -> void:
var env := environment
# Enable SDFGI
env.sdfgi_enabled = true
env.sdfgi_use_occlusion = true
env.sdfgi_read_sky_light = true
# Cascades (auto-scale based on camera)
env.sdfgi_min_cell_size = 0.2 # Detail level
env.sdfgi_max_distance = 200.0
LightmapGI (Baked Static Lighting)
When to Use
- Static architecture (buildings, dungeons)
- Mobile/low-end targets
- No dynamic geometry
Setup
# Scene structure:
# - LightmapGI node
# - StaticBody3D meshes with GeometryInstance3D.gi_mode = STATIC
# lightmap_baker.gd
extends LightmapGI
func _ready() -> void:
# Quality settings
quality = LightmapGI.BAKE_QUALITY_HIGH
bounces = 3 # Indirect light bounces
# Bake (editor only, not runtime)
# Click "Bake Lightmaps" button in editor
Environment & Sky
HDR Skybox
# world_env.gd
extends WorldEnvironment
func _ready() -> void:
var env := environment
env.background_mode = Environment.BG_SKY
var sky := Sky.new()
var sky_material := PanoramaSkyMaterial.new()
sky_material.panorama = load("res://hdri/sky.hdr")
sky.sky_material = sky_material
env.sky = sky
# Sky contribution to GI
env.ambient_light_source = Environment.AMBIENT_SOURCE_SKY
env.ambient_light_sky_contribution = 1.0
Volumetric Fog
extends WorldEnvironment
func _ready() -> void:
var env := environment
env.volumetric_fog_enabled = true
env.volumetric_fog_density = 0.01
env.volumetric_fog_albedo = Color(0.9, 0.9, 1.0) # Blueish
env.volumetric_fog_emission = Color.BLACK
ReflectionProbe
For localized reflections (mirrors, shiny floors):
# reflection_probe.gd
extends ReflectionProbe
func _ready() -> void:
# Capture area
size = Vector3(10, 5, 10)
# Quality
resolution = ReflectionProbe.RESOLUTION_512
# Update mode
update_mode = ReflectionProbe.UPDATE_ONCE # Bake once
# or UPDATE_ALWAYS for dynamic reflections (expensive)
Performance Optimization
Light Budgets
# Recommended limits:
# - DirectionalLight3D with shadows: 1-2
# - OmniLight3D with shadows: 3-5
# - SpotLight3D with shadows: 2-4
# - OmniLight3D without shadows: 20-30
# - SpotLight3D without shadows: 15-20
# Disable shadows on minor lights
@onready var candle_lights: Array = [$Candle1, $Candle2, $Candle3]
func _ready() -> void:
for light in candle_lights:
light.shadow_enabled = false # Save performance
Per-Light Shadow Distance
# Disable shadows for distant lights
extends OmniLight3D
@export var shadow_max_distance := 50.0
func _process(delta: float) -> void:
var camera := get_viewport().get_camera_3d()
if camera:
var dist := global_position.distance_to(camera.global_position)
shadow_enabled = (dist < shadow_max_distance)
Edge Cases
Shadows Through Floors
# Problem: Thin floors let shadows through
# Solution: Increase shadow bias
extends DirectionalLight3D
func _ready() -> void:
shadow_enabled = true
shadow_bias = 0.1 # Increase if shadows bleed through
shadow_normal_bias = 2.0
Light Leaking in Indoor Scenes
# Problem: VoxelGI light bleeds through walls
# Solution: Place VoxelGI nodes per-room, don't overlap
# Also: Ensure walls have proper thickness (not paper-thin)
Expert Techniques & Optimizations
1. Shadowmasking for Large Outdoor Scenes
Rendering real-time shadows for distant objects is too expensive. Use Shadowmasking by setting a DirectionalLight3D to the Dynamic bake mode while baking a LightmapGI. This bakes distant shadows into a texture while allowing dynamic objects to cast real-time shadows up close, preventing "double shadowing" artifacts.
2. Fake Global Illumination
If you cannot afford GI at all (e.g., strict mobile constraints), fake it! Duplicate your main DirectionalLight3D, rotate it 180 degrees (pointing up from the ground), turn Shadows OFF, set Specular to 0.0, and reduce Energy to 10-40%. This cheaply simulates bounced floor lighting.
3. Simulating PCSS (Contact-Hardening Shadows)
Godot's OmniLight3D scaling can simulate Percentage-Closer Soft Shadows (blurrier shadows further from the caster).
extends OmniLight3D
func _ready() -> void:
# Simulates area lights and Percentage-Closer Soft Shadows (PCSS).
# Note: High performance cost. Keep the number of lights with light_size > 0.0 low.
light_size = 0.5
shadow_enabled = true
# Distance fade culls the light and shadow completely when out of range,
# preventing the clustered renderer from choking on too many overlapping PCSS lights.
distance_fade_enabled = true
distance_fade_begin = 20.0
distance_fade_length = 5.0
Reference
- Master Skill: godot-master
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