Cel Shading

Cel shading converts continuous diffuse lighting into a small number of discrete bands, producing the crisp, ink-and-paint look found in anime, cartoons, and many stylized games. Genesis exposes three modes — Single, Stepped, and Ramp — and is designed to layer with the rim, specular, and outline features for a complete toon stack.

When to use it

Stylized characters that need a clean cartoon read.
Mobile / VR projects that benefit from flat color regions, which compress well and shade cheaply.
Hybrid PBR, where you keep specular and reflections physically based while quantizing only the diffuse term.

Difference from Unlit

Unlit drops scene lighting entirely. Cel shading keeps the light direction and shadows but quantizes their intensity, so you still get shape-defining shadow shapes and react to scene lights.

Modes

Genesis selects the mode with the Cel Mode dropdown (_CelMode):

Single — one hard threshold splits lit and shadow. Strongest comic-book read and the cheapest option.
Stepped — a configurable number of evenly spaced bands. Three is the most common; five to seven gives a softer, painted look.
Ramp — samples a 1D ramp texture by NdotL, handing art full control over colored shadows and warm-to-cool transitions. Author ramps with the Ramp Creator.

Standard Lambert diffuse — soft, continuous falloff.

Three discrete bands with a hard threshold edge.

Lit (PBR)

Cel · Stepped (3)

The same material with the diffuse term quantized into three bands. Drag to compare.

Properties

Inspector label	Shader property	Type	Default	Description
Cel Mode	_CelMode	enum	Single	Single, Stepped, or Ramp band model.
Threshold	_CelThreshold	Float (0–1)	0.5	Position of the shadow edge along NdotL. Single mode only.
Steps	_CelSteps	Int (1–8)	3	Number of light bands. Stepped mode only.
Edge Smoothness	_CelSmoothness	Float (0–1)	0.02	Anti-aliased width of band edges. Lower is sharper.
Ramp Texture	_CelRamp	Texture2D	None	1D ramp sampled by NdotL. Ramp mode only.
Shadow Color	_CelShadowColor	Color	RGB(0.18, 0.20, 0.28)	Tint applied to the shadow band; multiplies albedo.
Shadow Intensity	_CelShadowIntensity	Float (0–1)	1.0	Blend amount between lit albedo and the shadow tint.

Usage

Set the material’s Rendering Mode to Toon (recommended) or keep Lit for hybrid PBR + toon.
Enable Cel Shading in the inspector. Single mode is applied immediately.
Switch Cel Mode to Stepped and adjust Steps until the silhouette reads correctly at gameplay distance — three is a strong starting point.
For the polished look, switch to Ramp and assign a ramp texture authored in the Ramp Creator.
Layer Rim Lighting and Outline for the full toon stack.


// Drive cel shading at runtime via a Genesis material
material.SetFloat("_CelMode", 1);            // 0 = Single, 1 = Stepped, 2 = Ramp
material.SetInt  ("_CelSteps", 4);
material.SetColor("_CelShadowColor", new Color(0.20f, 0.22f, 0.30f));

Tips & gotchas

Use Edge Smoothness (_CelSmoothness) instead of texture filtering to anti-alias band edges — it preserves sharpness up close and softens only the edge.
Receive Shadows must be enabled on the renderer for cast shadows to feed NdotL; otherwise self-shadowing is the only contribution.
The Ramp Creator writes 256×4 ramp textures with linear sampling and no mipmaps. Match those settings if you author ramps externally to avoid banding.
Stepped mode at one step is not equivalent to Single mode — use Single for the lowest cost.

Specular Highlights — stylized highlights that pair with cel.
Rim Lighting — fresnel edge to complete the toon look.
Outline — inverted-hull and screen-space outlines.
Ramp Creator — author and edit ramp textures inside Unity.