screen-shake v0.0.5

screen-shake

Screen shake for JavaScript / TypeScript games

Based on this GDC talk by Squirrel Eiserloh

:sparkles: Features

• :+1: Works with any JS/TS rendering library or game engine
• :yum: Uses Perlin noise and exponential trauma for a more satisfying shake
• :zap: Around 700b and 0 dependencies
• :safety_vest: Fully typed

API

You first need to create an instance by using the default export

import createScreenShake from 'screen-shake'

const screenShake = createScreenShake()

Configuration options

createScreenShake({
  // The maximum amount of angle movement.
  maxAngle = 10,
  // The maximum amount of x offset movement.
  maxOffsetX = 30,
  // The maximum amount of y offset movement.
  maxOffsetY = 30,
  // How much trauma is reduced per update. Tweak this if you want to change the duration of the screen shake. A higher value means a shorter duration.
  traumaReductionPerUpdate = 0.02,
})

The screen shake instance has two methods:

add

(trauma: number) => void

How much trauma to add between 0 and 1 (equal to 100% trauma).

update

(time: number) => ({ angle: number, offsetX: number, offsetY: number })

Call this on every update of your game loop.

Has one argument, the time since update was first called. (This is used to smoothly interpolate the noise)

Returns an object with the values to add to your camera:

• angle - Add it to the cameras angle
• offsetX - Add it to the cameras x position
• offsetY - Add it to the cameras y position

Example

import createScreenShake from 'screen-shake'

// Create the instance. Configuration is optional.
const screenShake = createScreenShake()

if (projectileHit) {
  // Add 10% trauma when hit
  screenShake.add(0.1)
}

let time = 1

// Save a copy of the camera at the original position
const baseCamera = {
  angle: camera.angle,
  x: camera.x
  y: camera.y
}

gameLoop(() => {
  const { angle, offsetX, offsetY } = screenShake.update(time)

  camera.angle = baseCamera.angle + angle
  camera.position.x = baseCamera.x + offsetX
  camera.position.y = baseCamera.y + offsetY

  time++
})

:package: Install

npm install screen-shake

:book: Recipes

Export instance from file

Initialize the screen shake instance in a file and export the instance.

screenShake.ts

import createScreenShake from 'screen-shake'

export default createScreenShake()

Change screen shake speed

Modify time before passing it to update

Example with 50% speed:

screenShake.update(time * 0.5)