---
title: "Reactive psychedelic backgrounds"
package: "@phaser-ae/backdrop-trippatron"
tier: Pro
version: 3.0.0-3
released: 2026-10-14
updated: 2026-10-19
description: "Twenty full-screen neon backgrounds for psychedelic arcade arenas that bulge with explosions, pulse to the music and ripple behind a dragged finger."
url: https://phaser.io/packs/backdrop-trippatron
site: Phaser - https://phaser.io
---

# Reactive psychedelic backgrounds

A neon background that reacts to the game: the grid bulges where an explosion lands, the colours pulse with the music,
and a dragged finger leaves a wake like water. There are twenty styles, one call shows one, and every setting is live.

## What it does

You show a background with a style and its settings, and it fills the screen behind the sprites. The patterns are
worked out per pixel: where the pixel sits on a lattice, a ring, a spiral or a noise field. So there are no textures to
load, and the cost is one full-screen pass whatever the pattern. The colour is always a rainbow over the surface, set by
a base hue, a hue cycle per second and a brightness.

What makes it more than wallpaper is that it shares state with the `trippatron` pack. Every burst and every
`trip.impact` call pushes the surface outward from where it happened, with up to eight shared impulses in flight at
once. With audio composed and `trip.listen()` called, the level of the mix drives the wobble, brightness and hue, and
the waveform can be drawn as an oscilloscope trace. `handle.wake` sends a wave packet along a segment of the world, so
sampling a drag every tenth of a second leaves a trail of ripples; up to 24 wake segments are held at once.

It runs its own pass rather than joining the backdrop stack, because one surface needs far more data (the settings,
the impulses, a 32-sample waveform and the wake segments) than a stacked backdrop's sixteen params. Settings are
checked before anything changes, so a bad value throws and the old background stays.

## Features

- **Twenty styles** — `grid`, `rings`, `plasma`, `tunnel`, `raster`, `hex`, `triangles`, `diamonds`, `dots`,
  `checker`, `circuit`, `contours`, `interference`, `starfield`, `aurora`, `nebula`, `scanlines`, `waves`, `spiral`
  and `kaleidoscope`; `tripBackdropStyles` lists them for a picker.
- **Impact ripples** — explosions and impacts from `trippatron` displace the surface; `reaction` scales them or turns
  them off.
- **Audio response** — `audioGain` sets how much the mix moves the wobble, brightness and hue.
- **A live waveform** — `waveform: true` draws the signal as a trace across the middle.
- **Drag wakes** — `handle.wake` spreads a water-like wave along a drag or from a point, with its own strength, width,
  speed and duration.
- **Live settings** — spacing, line width, warp, rounding, speed (backwards too), hue, cycle and brightness, changed
  with `set`.
- **Checked input** — out-of-range numbers are clamped, and non-finite ones throw before anything is replaced.
- **WebGPU and WebGL2** — one full-screen pass on either.

## Good for

- **Twin-stick arena shooters** — a neon grid that warps with every explosion, in the style of Geometry Wars.
- **Light shows and psychedelic shooters** — hue cycling and kaleidoscopes in the style of Llamatron and Trip-a-Tron.
- **Music visualisers and rhythm games** — a surface that pulses to the mix and traces its waveform.
- **Touch toys and menus** — a background that ripples behind the player's finger.
- **Tunnel and tube shooters** — the `tunnel` and `spiral` styles for a sense of depth.

## Make it yours

Every setting is live. A calm menu is `starfield` or `aurora` with a slow `cycle`, low `brightness` and `reaction` at 0,
so bursts played over the menu do not shake it. A frantic arena is `grid` with fine `spacing`, some `rounding` so the
cells bulge, `warp` raised and `reaction` at 2, with `audioGain` and `waveform` on for the music. Changing style
mid-game is one `set`, as a level changes or a boss enters.

## A quick look

A grid that bulges at an impact, then turns into a kaleidoscope that pulses to the music:

```ts
const bg = game.tripBackdrop.show({ style: 'grid', spacing: 36, rounding: 0.6, warp: 15, brightness: 0.5 });
game.trip.impact({ x: 200, y: 180, strength: 40 });     // the grid bulges out from here
bg.set({ style: 'kaleidoscope', cycle: 0.2 });          // live
game.trip.listen();                                      // with audio composed: pulse to the mix
bg.set({ waveform: true, audioGain: 2 });
```

## Works with

- `trippatron` — required: its bursts and impacts move the surface, and it holds the shared audio state.
- `post-trippatron` — distorts the sprites with the arena; lower the reaction on one of the two so an impact does not
  double up.
- `audio` — real music for the surface to react to.
- `backdrops` — calm skies and stacked, fading parallax layers instead.

## Good to know

- One opaque background at a time: it hides any backdrop beneath it, and showing a new one replaces the old.
- The ripples are a formula over time, not a fluid simulation: eight shared impulses and 24 wakes at most, the oldest
  recycled.
- It does not distort sprites; that is `post-trippatron`.
- There are no colour params: the colour is always a rainbow set by hue, cycle and brightness.
- Changing scene removes it, so show it again in the next scene; before audio unlocks, the audio analysis is silence.

---

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