Rim Lighting

Rim Lighting traces a Fresnel-style glow around the silhouette of a mesh, separating characters from their backgrounds and adding the classic “key light from behind” feel. Genesis layers rotation, light-direction masking, and an HDR tint on top, so the rim reads as either a soft bloom or a hard cartoon edge.

Video

A character orbited by the camera against a dark background, a cyan HDR rim tracing the silhouette and shifting as the view angle changes, separating the figure from the backdrop.

features/rim-lighting/rim-orbit.mp4

A Fresnel rim separating a character from a dark background as the camera orbits.

When to use it

Characters that need silhouette separation in dark scenes.
Toon stack — pair with Cel Shading and Outline for the canonical anime look.
Sci-fi and hologram surfaces — push an HDR rim into bloom for a glowing edge.
Cinematic shots that want a hand-placed back-light without spawning a real light.

Difference from Outline

Outline is a hard, constant-width ink stroke. Rim is a soft fresnel gradient that fades into the lit surface. Most stylized characters use both — rim for read, outline for ink.

How it works

Genesis evaluates 1 - dot(N, V) (Fresnel), raises it to _RimPower, multiplies by _RimColor * _RimIntensity, then optionally masks the result by saturate(dot(N, L)) when Light Dependent is on. The rotation term rotates the normal in screen space before the Fresnel, which moves the rim around the silhouette.

Lit material with no edge glow.

A cyan fresnel glow, here masked to the side facing the key light.

Off

Rim · cyan, light-dependent

A character with and without rim lighting. Drag to compare.

Properties

Inspector label	Shader property	Type	Default	Description
Rim Color	_RimColor	Color (HDR)	RGB(1,1,1)	Rim tint. Use HDR for bloom-driven edges.
Power	_RimPower	Float (0.1–16)	4.0	Fresnel exponent. Higher gives a thinner rim.
Intensity	_RimIntensity	Float (0–8)	1.0	Overall multiplier.
Rotation	_RimRotation	Float (0–360)	0	Rotates the rim around the view axis, in degrees.
Light Dependent	_RimLightDependent	Toggle	Off	Off = full silhouette, On = masked by NdotL.
Softness	_RimSoftness	Float (0–1)	0.0	Smoothstep width applied before the power curve.
Rim Mask	_RimMask	Texture2D	None	Optional UV mask limiting rim to specific regions.

Usage

Enable Rim Lighting and set a color complementary to your scene’s key light.
Dial Power to 3–6 for a wide, soft rim, or 8–16 for a thin, sharp one.
Turn on Light Dependent so the rim appears only where the main light hits — far more believable for characters.
Use Rotation in cinematics to anchor the rim to a specific direction.


material.SetColor("_RimColor", new Color(0.4f, 0.9f, 1.0f) * 2.0f); // HDR
material.SetFloat("_RimPower", 6f);
material.SetFloat("_RimLightDependent", 1f);

Tips & gotchas

Use HDR colors (intensity above 1.0) only if your camera has a Bloom override; otherwise they clip.
High Power values look noisy on low-poly meshes — raise Softness or smooth the normals.
With Light Dependent and Cel Shading both on, the rim inherits the cel banding edge; this is expected.
Rotation is screen-space, so verify both eyes match in VR captures.

Cel Shading — toon diffuse beneath the rim.
Outline — hard ink stroke that pairs with rim.
Specular Highlights — specular lobe layered on top.
Emission — sustained glow versus the view-dependent rim.