---
title: "Skymax"
package: "@phaser-ae/skymax"
tier: Pro
version: 3.0.0-4
released: 2026-10-14
updated: 2026-10-19
description: "A physically based atmosphere with volumetric clouds, god rays, cloud shadows, a day clock and weather presets, for 3D skies and 2D backgrounds on WebGPU."
url: https://phaser.io/packs/skymax
site: Phaser - https://phaser.io
---

# Skymax

A sky with weight: a physically based atmosphere, volumetric clouds you can fly through, cloud shadows on the ground,
god rays through the gaps and a moonlit night with real stars. It lights the 3D scene beneath it, and it can also stand
behind a 2D game.

## What it does

Rayleigh and Mie scattering are integrated once into transmittance and multiple-scattering lookup tables, then into a
sky-view table. Every pixel of the dome, every cloud sample and every fogged surface reads from the same tables, so the
colours agree: the blue deepens toward the zenith, the horizon whitens with haze, and a low sun reddens because the
tables say it does.

The clouds are a cumulus shell marched through a noise volume, eroded at the edges and lit with multiple scattering.
Each frame only a fraction of the pixels is marched, and a reprojecting temporal resolve rebuilds the rest at full
detail. Clouds carry their own depth, so geometry in front of them hides them. A top-down cloud shadow map darkens the
ground and blocks the god rays, which `render-3d`'s shadow cascades block too, so a mountain or a mast throws a shaft.
An aerial-perspective pass fades distant surfaces toward the sky behind them.

A day clock places the sun and the moon on the arc for the observer's latitude, spins a star panorama about the pole
and eases the twilight. The sky bakes itself into a mipped environment map for anything reflective and writes
`render-3d`'s lighting record, so shadows, ambient and fog match the hour. In a 2D world, an independent background
camera renders the same atmosphere and clouds before the sprites, with no 3D scene needed.

## Features

- **A physically based atmosphere** — scattering through lookup tables shared by the sky, the clouds and the fog.
- **Volumetric clouds** — a shell you can fly through, rebuilt over a lattice of 4, or 2 for fast cameras.
- **Cloud shadows** — a shadow map over a box round the camera, 4,000 metres half-width by default, published for
  `render-3d` and `watermax`.
- **God rays** — marched through the cloud shadow and the scene's shadow cascades, tuned by the haze and the distance.
- **A day clock** — `time`, `hour`, `daySeconds` and `latitude`, with the moon on its own arc and a turning star
  panorama.
- **Eight presets** — among them `partlyCloudy`, `stunningSunset`, `thunderstorm`, `stormyEvening`, `moonlitNight`,
  `fluffy` and `hazy`.
- **Quality tiers** — `low`, `medium`, `high` and `ultra`, switched live.
- **Drives the lighting** — sun, ambient and fog written into `render-3d`, with auto exposure so a moonlit night is not
  black.
- **An environment map** — baked and mipped for water and reflective materials.
- **2D backgrounds** — a sky-only camera with yaw, pitch, field of view and altitude, behind the sprites.

## Good for

- **Open-world and flight games** — clouds the camera can climb into and through.
- **Sea and sailing games** — with `watermax` reflecting the sky and reading the same sun.
- **Landscapes** — cloud shadows drifting across the ground.
- **Cinematic moments** — sunsets that colour the clouds from below, god rays, a thunderstorm rolling in.
- **2D games with a dramatic sky** — a volumetric cloudscape behind side-on or top-down play.

## Make it yours

Start from a preset and change what you need. `apply` merges a partial set of parameters for the atmosphere, the sun,
the time, the clouds, the weather, the god rays and the night sky, and every field of `params` can be edited in place.
Options set the quality tier, the clock and latitude, which features run (clouds, god rays, cloud shadows, the
environment map and the lighting), the god-ray step count, a cloud wind that outlives every preset, and the moon, star
and cirrus textures.

Two very different uses: an open 3D world at high quality with a two-minute day, cloud shadows on the terrain, god
rays, and the lighting driven by the sky; and a 2D side-scroller with the `fluffy` preset, a still clock, a background
view tilted up 30 degrees, and the environment map, cloud shadows, lighting and god rays switched off because nothing
3D reads them.

## A quick look

A sunset preset with a two-minute day, more cloud and stronger god rays:

```ts
game.skymax.preset('stunningSunset');
game.skymax.daySeconds = 120;
game.skymax.apply({ cloud: { shape: { coverage: 0.6 } }, godRays: { strength: 1 } });
```

## Works with

- `render-webgpu` — the backend it needs; there is no WebGL fallback.
- `render-3d` — its lighting is driven by the sky, and its shadow cascades cast god rays.
- `watermax` — reflects the environment map and reads the same sun.
- `terrain-3d` — its ground takes the cloud shadow.
- `world-side` and `world-topdown` — the 2D worlds it can stand behind.
- `sky-3d` — the light, painted sky on WebGPU and WebGL2; compose one or the other, never both.

## Good to know

- WebGPU only, and far heavier than `sky-3d`; choose `quality: 'low'` for integrated GPUs.
- The clouds resolve over a few frames when the camera moves fast; `lattice: 2` halves the wait at twice the cost.
- Distances are metres and the clouds sit thousands of units up, so scale the world to match or push the far plane
  past them.
- The aerial-perspective fog needs kilometres of scene to show, and a 2D scene has no depth fog, ground shadows or
  geometry god rays.
- The exposure meter reads the sky and the sun, not the frame, so a dark cave under a bright sky is metered for the sky.

---

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