constellation-canvas

Draws cute animated canvas constellations.

See it in action here!

Usage (webpack+babel)

Grab the code from here or npm

npm install constellation-canvas --save

#or#

git checkout git@github.com:thenextweb/constellation.git
npm install

Then just import it and feed it some parameters. There's a full list below.

import Constellation from 'constellation-canvas';

const ellation = new Constellation({
    size:[500,800],
    canvas: document.querySelector('canvas'),
    starCount: 30,
    lineCount: 60,
    style: {
        starSize: 4,
        starPadding: 5
        lineSize: 2
    }

});

Usage (browser)

Grab the latest release and drop it in as a script tag. window.constellation will appear

Parameters

All of them are optional but you might want to change some

Name	Type	Description
size	array [x,y]	Pixel size for the canvas
padding	array [x,y]	Space between the canvas edges and the stars, it can be negative to make a full background
canvas	DOM element	The canvas element to draw in. Will be created if it doesn't exist
starCount	number	Total number of stars to draw
lineCount	number	Total number of lines drawn between stars
🏃‍💨
speed	object	Speed options
speed.active	number	Speed when the mouse is moving the stars
speed.passive	number	Speed when the stars are jiggling by themselves
👩‍🎨
style	object	Style options
style.starSize	number	Size of the stars
style.starColor	string	Color of the stars
style.starPadding	number	Space between stars and lines
style.lineColor	string	Color of the lines
style.lineSize	number	Size (line weight) of the lines

Drawing things yourself

For further customization you can also pass an onDraw parameter with a number of callbacks. These will allow you to take over the drawing process of the canvas.

let constellation = Constellation({
    size:[500,800],
    canvas: document.querySelector('canvas'),
    onDraw: {
        afterStar: (ctx,style,star) => {
            ctx.fillStyle = 'rgba(0,0,0,0)';
            ctx.beginPath();
                ctx.arc(
                    node.pos[0], node.pos[1], style.starSize,0, 2 * Math.PI
                );
                ctx.globalCompositeOperation = 'destination-over';
                ctx.shadowColor = '#999';
                ctx.shadowBlur = 20;
                ctx.shadowOffsetX = 0;
                ctx.shadowOffsetY = 15;
                ctx.fill();
            ctx.closePath();
            ctx.fillStyle = style.starColor;
        }
    }
});

You can see how these plug in at src/class/Canvas.js for yourself to better understand what's happening but here's a quick reference.

Callback	Description
star(ctx,style,star)	overrides star drawing. star contains the coordinates for the star to be drawn
afterStar(ctx,style,star)	takes place after the default star drawing. star contains the coordinates for the star that was drawn
line(ctx,style,line)	overrides line drawing. line contains the coordinates for the line to be drawn
afterLine(ctx,style,line)	takes place after the default line drawing. line contains the coordinates for the line that was drawn
afterFrame(ctx,style,objects)	takes place after drawing a full frame. objects contains all coordinates for stars & lines

For afterStar & afterLine you have to reset all fillStyles and whatnot or otherwise they'll carry over into the built-in drawing code. Good news is that for performance reasons you'll probably want to avoid afterStar & afterLine anyway and instead provide a full drawing solution or plug into afterFrame.

Advanced

There are some extra advanced properties too! fuzziness for controlling how reactive to the mouse stars are and scale, for drawing the canvas at a different resolution (it's @2x by default). Check out the code (i mean it's like 5? files total) to see how they work.

ALSO!! should you ever need it, Constellation will return a promise containing $constellation, the canvas DOM object after everything there has been done.

const constellation = Constellation({
    /*blah*/
});

constellation.then(function(data){
    console.log(data.$constellation);
})