claude-dev-suite Unity 2D Lighting
URP 2D Renderer setup
1. Project Settings > Graphics → URP Pipeline asset assigned.
2. Create Renderer2DData asset → assign to URP asset's Renderer List.
3. Camera component → Render Type = Base; Renderer = the 2D renderer.
Without the 2D Renderer assigned, Light 2D components do nothing.
Light 2D types
| Type | What |
|---|---|
| Global Light | Ambient color + intensity for the entire scene (replaces clear-color lighting) |
| Freeform | Polygon-shaped light (room interior, lava pool) |
| Point | Circular falloff (torch, glow) |
| Sprite | Light shape derived from a sprite (any artist-defined falloff) |
| Parametric | N-sided polygon (legacy; prefer Freeform) |
Common setup: one Global Light per scene (low intensity for darkness) + per-object Lights to highlight key elements.
Blend Styles
Renderer2DData defines up to 4 blend styles. Each has:
| Setting | Effect |
|---|---|
| Blend Mode (Multiply / Additive) | Multiply darkens unlit areas (standard); Additive brightens |
| Render Texture Scale | 0.5 = half-res light buffer (perf win, slight blur) |
| Use Depth/Stencil | Required for Shadow Casters |
| Mask Channel | Maps Sprite Renderer's Mask Interaction to specific channels |
Default blend style 0 ("Default") is enough for most projects. Add more only if you need separate light groups (e.g. "Underwater" with blue cast).
Shadow Casters 2D
On a sprite that should cast shadows:
Add ShadowCaster2D component → Self Shadows = OFF (default), Casts Shadows = ON.
Mesh: Use Renderer Silhouette (auto from sprite) or Custom Shape.
On the Light 2D:
Shadow Intensity > 0 → enables shadows from casters.
Composite Shadow Casters 2D group multiple casters with same parent transform — important for moving multi-part characters.
Sprite Mask
Stencil-like masking — show a sprite only where another sprite is visible.
Sprite Mask GameObject (with SpriteMask component) defines the mask shape.
Sprite Renderer → Mask Interaction =
None (default)
Visible Inside Mask (clipped to mask shape)
Visible Outside Mask (cut hole)
Use cases: 2D fog of war reveal, light cone visibility, transition wipes.
Normal-mapped sprites
For dynamic 2D lighting that respects sprite geometry:
- Author normal map (Sprite Lamp, NormalPainter, or Aseprite normal export).
- Set the secondary texture on the sprite: Sprite Editor → Secondary Textures → name
_NormalMap, drag normal texture. - Material → use the Sprite-Lit-Default shader (URP); plug
_NormalMapif needed. - Light 2D → Use Normal Map = ON.
Sprites pop with bumpy 3D-looking lighting from 2D Lights. Heavy on fillrate — use sparingly.
Anti-patterns
| Anti-pattern | Fix |
|---|---|
| Adding Light 2D without 2D Renderer | Configure Renderer2DData asset on the URP renderer list |
| Many overlapping point lights with Shadow Intensity 1 | Lower res for shadow buffer; combine via blend styles |
| Self Shadows ON by default | OFF unless deliberately needed (causes z-fighting on sprites) |
Sprite Mask without Mask Interaction set on target |
Set Mask Interaction on every sprite that should be clipped |
| Normal maps on every sprite | Only on hero/lit-emphasis sprites — fillrate cost |
Production checklist
- Renderer2DData assigned + camera using 2D renderer
- Global Light per scene set deliberately (not default)
- Shadow Casters 2D placed on geometry that should cast
- Composite Shadow Caster on multi-part characters
- Blend styles configured if multiple light groups
- Sprite Masks tested in build (not just editor)
- Normal mapping budgeted (fillrate measured)