Skip to content
T1KTheOneKit

t1k:unity:rendering:shadow-optimization

FieldValue
Modulerendering
Version3.1.7
Efforthigh
Tools—

Keywords: optimization, rendering, shadows, unity

How to invoke

Section titled “How to invoke”
/t1k:unity:rendering:shadow-optimization

Unity Shadow Optimization Skill

Section titled “Unity Shadow Optimization Skill”

Triggers

Section titled “Triggers”
  • shadow, shadow map, shadow resolution, cascade, soft shadows
  • light probe, light probe group, probe placement
  • baked indirect, mixed lighting, lightmap bake
  • shadow acne, shadow bias, shadow distance
  • ShadowCastingMode, shadow casting

URP Shadow Settings Reference

Section titled “URP Shadow Settings Reference”

Key YAML Fields (UniversalRP.asset)

Section titled “Key YAML Fields (UniversalRP.asset)”
m_MainLightShadowmapResolution: 1024  # 256/512/1024/2048/4096
m_ShadowDistance: 30                    # Max shadow render distance (meters)
m_ShadowCascadeCount: 2                # 1-4 cascades
m_Cascade2Split: 0.3                   # % of distance for near cascade
m_SoftShadowsSupported: 1              # 0=off, 1=on
m_SoftShadowQuality: 2                 # 0=Low, 1=Medium, 2=High
m_ShadowDepthBias: 2                   # Reduce shadow acne (1-3)
m_ShadowNormalBias: 2                  # Reduce shadow acne (1-3)
Section titled “Recommended Settings by Arena Size”
ArenaResolutionDistanceCascadesSplit
Small (20×20)512201—
Medium (40×40)10243020.3
Large (80×80)20485030.1/0.3
Open world4096100+40.067/0.2/0.467

Cascade Strategy

Section titled “Cascade Strategy”
  • 1 cascade: Uniform texel density — ok for small arenas
  • 2 cascades: Near cascade (30% distance) gets 4× texel density — best for fixed-camera arenas
  • 3-4 cascades: Needed for large worlds with close-up + distant shadows

Per-Entity Shadow Control

Section titled “Per-Entity Shadow Control”

ShadowCastingMode Options

Section titled “ShadowCastingMode Options”
renderer.shadowCastingMode = ShadowCastingMode.Off;        // No shadow
renderer.shadowCastingMode = ShadowCastingMode.On;         // Normal shadow
renderer.shadowCastingMode = ShadowCastingMode.TwoSided;   // Both faces cast
renderer.shadowCastingMode = ShadowCastingMode.ShadowsOnly; // Invisible, shadow only

Shadow Policy Table

Section titled “Shadow Policy Table”
Entity TypeShadowReason
Units (characters)ONVisual grounding
Trees/obstaclesONEnvironment grounding
Boundary wallsONArena structure
TerrainReceive onlyGround plane
Arrows/projectilesOFFToo fast, invisible
AOE/VFX (transparent)OFFNo meaningful shadow
ParticlesOFFPerformance waste
UI elementsOFF2D overlay

Light Probes for DOTS

Section titled “Light Probes for DOTS”

Placement Pattern (Grid)

Section titled “Placement Pattern (Grid)”
const float probeSpacing = 2f;      // 2m grid
const float groundOffset = 0.5f;    // Near ground
const float upperHeight = 3f;       // Captures tree canopy shadows


// 2-layer grid: ground + upper
for (z) for (x) {
    positions.Add(new Vector3(px, groundOffset, pz));
    positions.Add(new Vector3(px, upperHeight, pz));
}

Probe Count Estimation

Section titled “Probe Count Estimation”
  • (ArenaWidth/spacing + 1) × (ArenaDepth/spacing + 1) × 2 layers
  • 40×40 arena, 2m spacing → 21×21×2 = 882 probes

DOTS Compatibility

Section titled “DOTS Compatibility”
  • Entities Graphics auto-samples light probes — NO extra components needed
  • Probes must be in main scene (not SubScene)
  • Zero runtime cost — probes are baked SH coefficients

Mixed Lighting (Baked Indirect)

Section titled “Mixed Lighting (Baked Indirect)”

Setup

Section titled “Setup”
  1. Directional Light → lightmapBakeType = LightmapBakeType.Mixed
  2. URP Asset → m_MixedLightingSupported: 1 (default)
  3. Static flags on all arena objects (isStatic = true)
  4. Window → Rendering → Lighting → “Generate Lighting” (manual bake)

How It Works

Section titled “How It Works”
  • Realtime shadows for ALL objects (static + dynamic)
  • Baked indirect bounce for static geometry only
  • Units auto-sample light probes for ambient variation

Gotchas

Section titled “Gotchas”
  1. Shadowmask NOT supported by Entities Graphics — use Baked Indirect only
  2. SubScene = 1 lightmap per SubScene — ok for single SubScene
  3. Auto-generate lighting DISABLED with Entities Graphics installed — must bake manually
  4. GPU Resident Drawer “OnDemand” shadow bug — use “EveryFrame” mode if shadows flicker (note: invisible entities are more likely ChunkWorldRenderBounds NaN corruption — see #9)
  5. Bias too low → shadow acne (striping). Bias too high → peter-panning (shadows detach)
  6. Shadow distance > arena diagonal wastes texels on empty space
  7. Soft shadows add ~0.1ms GPU cost — negligible on modern GPUs
  8. Forward+ has no GBuffer pass — affects impostor baking, not shadows

→ See references/shadow-safety-guide.md for Safe vs Unsafe shadow change table, CRITICAL lighting corruption gotchas, and Rendering Debugger workflow.