Asif Bacchus c145426d69 proofread

2020-04-10 12:50:16 -06:00

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ab-particles: vanilla javascript particle animation

Very simple, lightweight animated particles display that does not require any external files whatsoever. No libraries, configuration JSON or anything. This is a stripped-down version of the famous 'js-particles' by Vincent Garreau and the code was inspired by an amazing tutorial by Franks Laboratory.

Features

One single file to link, no external libraries or function calls.
- Minified version is only 5KB!
- Vanilla javascript -- no jQuery, node.js or anything else.
You do NOT have to link/learn/write any external configuration files, libraries or functions. Everything you need to know is in this readme.
Colours are all set by CSS variables so theme integration is easy, no custom functions to write or libraries to figure out.
All features are enabled/configured based on parameters passed directly to the javascript function.
Mouse effects (only 2... for now):
- Particle repulsion
- Connection-line highlighting with configurable colour

Usage (simple)

Download the release file.
Edit your HTML to include a canvas with ID 'particles'. You can put the canvas anywhere you'd like, but I'd strongly recommend putting it at the end of the body.
```
...
<canvas id='particles'></canvas>
</body>
```
Every particles implementation I've seen relies on it being full-window. This one is no different, all the calculations are done under that assumption. Therefore, we should remove the canvas from the document flow and make it full width and height. Your CSS should look something like this:
```
#particles {
    position: fixed;
    top: 0;
    left: 0;
    height: 100%;
    width: 100%;
    z-index: -999;
}
```

Link your preferred file to your HTML. I find the best results are combining defer and loading the script at the end of the body. I'm using the minified version here:

<body>
    ...
    <canvas id="particles"></canvas>
    <script
        src="js/ab-particles.min.js"
        crossorigin="anonymous"
        integrity="sha384-eUruDNgO8YkfdY2sU3oCkjzhJbnXXT9kac3I8DwYkh2mjE0jCIKvTgN6yvvo9SqO"
        defer>
    </script>
</head>

Because the script reads CSS variables, we need to wait until CSS is fully parsed. Add an onload event to the body tag of your HTML:
```
<body onload="particles()">
```

CSS customizations (colours)

The default colours are boring! If you want to match the particles to your site's colour scheme, you just have to add some variables to your CSS. It's considered best practice to add variables to the root element, but you can add these variables directly to your canvas if you'd prefer.

These are the 3 variables read by the script and what they do:

variable	purpose	default
--col-particle	Colour of the particle itself (little circle).	black (#000000)
--col-particle-stroke	Colour of the connecting lines.	black (#000000)
--col-particle-stroke-hover	Colour of connecting lines on mouse hover. You do not need to define this at all if you set the hover parameter to false	red (#ff0000)

You can set these variables as follows (I'm setting them on the root element). In this example, I'm setting a few shades of blue:

:root {
  --col-particle: #536878;
  --col-particle-stroke: #035096;
  --col-particle-stroke-hover: #0892d0;
}

Setting feature parameters

Everything that can be customized about the script is done via parameters passed directly to the particles() function. This avoids any need for configuration files and makes it easy to remember how to make changes. If you screw up a parameter's setting, the script will just use it's internal defaults and will display a helpful message on the console which you can view by turning on your 'developer tools'.

All parameters have default settings so none of them are required. Also, since this is javascript, the parameters are cAsE seNsiTiVe. The order does not matter. These are all the available parameters, what they do and their default settings.

parameter	purpose	allowed values	default
opacity	Overall opacity of the canvas element itself including all contents.	0 - 100	100
numParticles	Number of particles displayed in the window. Calculated as a percentage-multiple of the window width. For example, if the window is 500px wide and numParticles=10, 50 particles will be drawn. Do not set this number too high or you can crash the browser!	finite number	10
sizeMultiplier	Random multiplier between 0 and this number that is applied to vary the size of the particles so they aren't all uniform.	finite number	5
width	Stroke width (px) of connector lines.	integer	1
connections	Whether or not to connect the particles to each other when they get close enough.	boolean	true
connectionDensity	How densely particles connect to each other. Careful not to set this number too high or you can crash the browser!	finite number > 1	15
speed	How quickly the particles bounce around the window	1 < integer < 1000	50
hSpeed	How quickly the particles move horizontally. Positive values move to the right, negative to the left. This overrides the value of 'speed'.	-1000 < integer < 1000	1
vSpeed	How quickly the particles move vertically. Positive values move down, negative move up. This overrides the value of 'speed'.	-1000 < integer < 1000	1
avoidMouse	Should particles be repelled away from the mouse?	boolean	true
hover	Should connection lines change colours when the mouse is near them?	boolean	true

Examples

default settings (explicit)

Random balanced horizontal and vertical motion bouncing off the edges of the window. Particles are repelled by the mouse and connections are highlighted on hover. Sample

<body onload='particles(opacity=100, numParticles=10, sizeMultiplier=5, width=1, connections=true, connectionDensity=15, speed=50, avoidMouse=true, hover=true)'>

starry night

Freeze the display, remove connections, disable mouse interaction. Creates a random assortment of particles that will change on each reload. Sample

<body onload='particles(speed=0, connections=false, avoidMouse=false, hover=false)'>

snow

No horizontal movement, connections or mouse interaction. Particles fall straight down. Sample

<body onload='particles(hSpeed=0, vSpeed=100, connections=false, avoidMouse=false, hover=false)'>

bubbles

Opposite of snow, looks a little like bubbles. Sample

<body onload='particles(hSpeed=0, vSpeed=-100, connections=false, avoidMouse=false, hover=false)'>

warp speed to the right

Moving right would make the particles go left, therefore negative movement. We don't want connections or mouse interaction here either. Sample

<body onload='particles(vSpeed=0, hSpeed=-100, connections=false, avoidMouse=false, hover=false)'>

warp speed to the left

Moving left would make the particles go right, therefore positive movement. We don't want connections or mouse interaction here either. Sample

<body onload='particles(vSpeed=0, hSpeed=100, connections=false, avoidMouse=false, hover=false)'>

my usual settings (nice background effect)

I use this for screens where I can't figure out a meaningful background, so why not generate something nice to look at? Sample

<body onload='particles(speed=15, avoidMouse=false)'>

Advanced loading

Sub-resource Integrity (SRI)

I've included the proper checksums to use when loading either version of the script and using Sub-Resource Integrity (i.e. 'integrity' checksums). Lookup the version of the script you're linking and paste the checksum into the integrity attribute of the link tag. I included an example earlier in this document.

Do not simply copy the checksum in this document! Always get the correct checksum from the js/integrity.sha384 file included in this repo!

addEventListener

If you want to load the script using a javascript file instead of an inline onload attribute in your HTML, you can do it like this:

window.addEventListener('load', function(){
    particles(speed=15, avoidMouse=false)
}, false);

Again, I recommend using load instead of something like DOMContentLoaded since this script reads colour variables from CSS.

Notes

I use position: fixed in my CSS but you can just as easily use position: absolute. It makes no difference. The key is setting the canvas object to cover the entire window starting at the top left (0,0) and covering 100% height and width.
The z-index is set to a very low number so that the canvas falls behind everything else. Otherwise, you'll get particles floating over your text and interfering with pointer-events like links!
Certain parameters can overload the browser by drawing too many particles and/or calculating too many connections. Don't pick crazy numbers and you'll be fine.
numParticles is a multiplier. The script takes 1% of the window width and sets that as the number of particles it will generate multiplied by the value of numParticles. It is because this is a multiplier that you need to be careful about setting high values!
I don't really like most of the popular animations such as clicking to add more particles or 'grabbing' particles on hover/click. As such, I have not implemented these animations. Let me know if this is something you want!

Final thoughts

I put this together pretty quickly to generate a less boring background for a login page I was working on. As such, I didn't really add many bells and whistles. I wanted to keep it pretty lean and focussed. Also, this is one of the first javascript projects I've decided to 'release into the wild' for others to use. So, I'd love any feedback, suggestions and improvements you have to offer! I'm a horrid programmer so don't worry, I won't be offended by any criticism and look forward to maybe learning a few things from your suggestions!

Hope you find this useful. Please file issues/suggestions in the issues section.

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