VFXBeginner

Light Flicker

A torch that trembles like a real flame — smooth noise on a light's intensity turns static lighting into weather.

vfxlightingambiencefire

Examples

Captured from this page's own interactive demo below.

Overview

A perfectly steady light source reads as electric; a trembling one reads as alive. Light flicker drives a lamp's intensity (and ideally its radius and warmth) with smooth noise, and suddenly the torch is burning instead of just being on. It's the cheapest ambience effect that exists — one noise lookup per frame — and it animates every surface the light touches for free.

The critical word is SMOOTH: sample Perlin-style noise and the flame wanders organically; sample raw random every frame and you get a broken fluorescent tube — which is its own effect, but a horror-genre one. Layer two noise frequencies (a slow breathing drift plus small fast trembling) and vary the position slightly along with intensity, because real flames move as well as dim.

Flicker is also a storytelling channel: calm hearth in the safe room, nervous guttering when the wind picks up, a hard dropout right before the scare. Give the noise amplitude and speed to the designers as knobs, and make sure the flicker never crosses the readability floor — a light the player navigates by can breathe, but it must not black out gameplay information at random.

Interactive Demo

smooth noise, two octaves — Gust guts the flame for a beat

Flicker Depth25%

Flicker Speed1.5×

Use Cases

Torches, candles and campfiresFaulty electric lights in horrorLightning and storm ambienceSci-fi consoles and unstable machinery

Best Practices

Do

✓Drive intensity with SMOOTH noise (Perlin), never per-frame random — flames wander, they don't strobe.
✓Layer a slow drift with a small fast tremble, and move the light's position a little along with it.
✓Expose amplitude and speed as design knobs — the same script is a hearth at 10% and a dying torch at 50%.

Don't

✕Don't let a navigation-critical light flicker below the readability floor at random.
✕Don't flicker every light in the scene from the same clock — offset each source's noise or they pulse in unison.
✕Don't run flicker on dozens of expensive shadow-casting lights; fake the distant ones with emissive materials.

Common Mistakes

⚠Raw Random.value flicker shipped as a torch and reading as a broken office tube.
⚠All the torches in the dungeon flickering in perfect sync because they share Time.time with no per-light seed.
⚠Flicker applied to intensity only, while radius and color stay frozen — the light trembles but the flame doesn't.

Implementation

Paste this into your AI assistant (Cursor, Copilot, Claude) to add the effect to your project.

Prompt

Add the "Light Flicker" game-feel effect to my project: A torch that trembles like a real flame — smooth noise on a light's intensity turns static lighting into weather.

How it works: A perfectly steady light source reads as electric; a trembling one reads as alive. Light flicker drives a lamp's intensity (and ideally its radius and warmth) with smooth noise, and suddenly the torch is burning instead of just being on. It's the cheapest ambience effect that exists — one noise lookup per frame — and it animates every surface the light touches for free.

Guidelines:
- Drive intensity with SMOOTH noise (Perlin), never per-frame random — flames wander, they don't strobe.
- Layer a slow drift with a small fast tremble, and move the light's position a little along with it.
- Expose amplitude and speed as design knobs — the same script is a hearth at 10% and a dying torch at 50%.

Avoid:
- Don't let a navigation-critical light flicker below the readability floor at random.
- Don't flicker every light in the scene from the same clock — offset each source's noise or they pulse in unison.
- Don't run flicker on dozens of expensive shadow-casting lights; fake the distant ones with emissive materials.

Implement the effect in whatever engine/stack the project already uses and follow its existing code style. Wire it up where it makes sense.