sprinkler

sprinkler.js

With Sprinkler you can create an image rain on canvas. Give it a canvas element and a list of image URLs and call start() to make it animate dropping particles e.g. bananas or frogs or anything you can imagine. There are lots of parameters to tweak particle movement and transparency. Have fun!

Compatible with all the browsers that support canvas.

Examples

• Snowfall
• Money
• Fire
• Bananas
• Love
• Rainy Night, suitable for projection mapping.

Usage

The following will make the canvas rain anvils which accelerate at equal speed.

var c = document.getElementById('canvas')
var s = sprinkler.create(c)

var images = [
  'img/rusty-anvil.png',
  'img/steel-anvil.png'
]
var stop = s.start(images, {
  ddyMin: 400,
  ddyMax: 400
})

Installation

Browsers

<script src="https://unpkg.com/sprinkler@1.0.0/dist/sprinkler.min.js"></script>
<script>
  var c = document.getElementById('canvas')
  var s = sprinkler.create(c)

CommonJS & Node.js

Install via npm:

$ npm install sprinkler
---
var sprinkler = require('sprinkler')

AMD & Require.js

define(['scripts/sprinkler'], function (sprinkler) { ... });

API

sprinkler.create(canvasElement)

Create a sprinkler animation on the given canvas.

start(imageUrls, options)

Start the animation. Animation downloads the images in a lazy manner: instead of downloading all the images as soon as possible, it downloads an image when the image is dropped to the canvas as an particle. This feature allows you to specify even a large number of different images. Our current record is 3300.

Returns a stop function that stops the particle generation. Sprinkler allows you to run multiple start calls, also called waves, concurrently without stopping any.

Optional options object can take following properties:

• imagesInSecond, an average number of dropped images in a second per 1000 pixels of width. Bound to the width to keep the density the same regardless the canvas width.
• burnInSeconds, number of seconds to prerun the wave. This allows there to be visible particles already at the beginning. To get an instant feeling of a consistent flow, set higher than what it would take for a particle to fall through the canvas.
• zMin and zMax, range for initial scale. Between [0, Inf]
• rMin and rMax, range for initial rotation. Between [0, 2*Math.PI]
• aMin and aMax, range for initial transparency (alpha). Between [0, 1]
• dxMin and dxMax, range for horizontal velocity. Between [-Inf, Inf]
• dyMin and dyMax, range for vertical velocity. Between [0, Inf]
• dzMin and dzMax, range for scale velocity. Between [-Inf, Inf]
• drMin and drMax, range for rotation velocity. Between [-Inf, Inf]
• daMin and daMax, range for transparency velocity. Between [-Inf, Inf]
• ddxMin and ddxMax, range for horizontal acceleration. Between [-Inf, Inf]
• ddyMin and ddyMax, range for vertical acceleration. Between [0, Inf]
• ddzMin and ddzMax, range for scale acceleration. Between [-Inf, Inf]
• ddrMin and ddrMax, range for rotation acceleration. Between [-Inf, Inf]
• ddaMin and ddaMax, range for transparency acceleration. Between [-Inf, Inf]

Values are picked randomly but uniformly from the given ranges.

Default values are:

{
  imagesInSecond: 7,
  burnInSeconds: 0,
  zMin: 0.38, zMax: 1,
  rMin: 0, rMax: 2 * Math.PI,
  aMin: 1, aMax: 1,
  dxMin: -1, dxMax: 1,
  dyMin: 100, dyMax: 100,
  dzMin: 0, dzMax: 0,
  drMin: -1, drMax: 1,
  daMin: 0, daMax: 0,
  ddxMin: 0, ddxMax: 0,
  ddyMin: 0, ddyMax: 0,
  ddzMin: 0, ddzMax: 0,
  ddrMin: 0, ddrMax: 0,
  ddaMin: 0, ddaMax: 0,
}

stop()

Stops the animation. It is returned by start(...).

Notes for developers

Run tests with $ npm test.

Build with $ npm run build.

Serve with $ npm start.

Versioning

Semantic Versioning 2.0.0

License

MIT License