Reflection & Refraction

Reflection & Refraction stacks two related effects: a cubemap or reflection-probe lookup, and screen-space refraction via the URP Opaque Texture. Together they cover glass, ice, gemstones, water surfaces, and stylized crystal, with optional blur for frosted finishes and chromatic aberration for prismatic edges.

Video

A glass gemstone rotating in front of a detailed background, the background refracting and warping through it with chromatic aberration on the edges and a cubemap reflection sliding across the surface.

features/reflection-refraction/glass-refraction.mp4

Screen-space refraction and cubemap reflection on a rotating glass gem.

When to use it

Glass, ice, and gemstones — reflection and refraction layered together.
Calm water — reflection only, with a horizon fade.
Holographic UI — high refraction, low reflection, with a chromatic shift.
Stylized crystals — push blur and chromatic aberration for the cartoon-crystal look.

Difference from MatCap

MatCap is view-space and ignores the scene. Reflection & Refraction sample the actual world, responding to lights, probes, and on-screen geometry. Use MatCap for stylized metals and Reflection/Refraction for real glass.

Modes

Reflection — samples either an assigned cubemap or the active URP reflection probe through the standard glossy-environment path. Roughness picks the cubemap mip.
Refraction — distorts the URP Opaque Texture by the view-space normal, scaled by index of refraction.

Glass reads as a flat tinted surface.

The background distorts through the glass with a slight frost.

No refraction

Refraction · IOR 1.5 + blur

Tinted-transparent glass against full refraction with blur. Drag to compare.

Properties

Inspector label	Shader property	Type	Default	Description
Reflection Cubemap	_ReflectionCubemap	Cubemap	None	Optional override; falls back to the active reflection probe.
Reflection Strength	_ReflectionStrength	Float (0–1)	0.5	Mix between reflection and surface color.
Reflection Roughness	_ReflectionRoughness	Float (0–1)	0.2	0 = mirror, 1 = matte. Selects the cubemap mip.
Index of Refraction	_RefractionIOR	Float (1–2.5)	1.45	Glass 1.5, water 1.33, diamond 2.4.
Refraction Strength	_RefractionStrength	Float (0–2)	1.0	Multiplier on the distortion amount.
Refraction Blur	_RefractionBlur	Float (0–6)	0.0	Frosted-glass mip bias.
Chromatic Aberration	_ChromaticAberration	Float (0–0.05)	0.0	Per-channel UV offset on the refraction sample.
Fresnel Power	_FresnelPower	Float (0.1–8)	5.0	Biases reflection toward grazing angles.

Usage

Add a Reflection Probe to the scene if you do not already have one; URP needs it for the environment sample.
Enable the Opaque Texture option on the URP Asset (required for refraction).
Switch the material’s Blend Mode to Transparent and set the queue to 3000 or higher.
Dial IOR until the refraction looks right — 1.5 for glass, 1.33 for water.


material.SetFloat("_RefractionIOR", 1.5f);
material.SetFloat("_RefractionBlur", 2.0f);
material.SetFloat("_ChromaticAberration", 0.003f);

Tips & gotchas

The Opaque Texture is mandatory for refraction. Without it, the refraction term reads black.
Refraction only includes opaque geometry, so two refractive panes in front of each other will not see each other.
Blur cost scales with mip count; keep blur below 3 on mobile.
Refraction is per-eye and handles stereo UVs correctly in URP 12+.

Surface Settings — switch to Transparent for refraction.
Iridescence — view-angle rainbow on top of reflection.
MatCap — cheaper alternative for stylized metals.
Depth Coloring — pair with refraction for stylized water.