led.js

var ws281x = require('rpi-ws281x');

const config = {
    leds: 144 * 2,
    type: "grb",
    brightness: 255
};

function init(){
    ws281x.configure(config);
}

const pixels = new Uint32Array(config.leds);

let rg = 0;
let gg = 0;
let bg = 0;
let brightnessG = 1;

function setColor(r, g, b, render = true){
    rg = r;
    gg = g;
    bg = b;
    pixels.forEach((p,i) => setColorForPixel(i, r, g, b, false));

    render && ws281x.render(pixels);
}

function setColorForPixel(index, r, g, b, render = true){
    pixels[index] = (r << 16) | (g << 8) | b;
    render && ws281x.render(pixels);
}

const fixed = (inNumber) => Number.parseFloat(inNumber.toFixed(2));
const tween = (sourceVal, targetVal, t) => fixed(((targetVal - sourceVal) * t) + sourceVal);


function tweenToColor(r, g, b){
    const previousR = rg;
    const previousG = gg;
    const previousB = bg;
    
    let i = 0;
    while(i < 1){
        i += .01;
        setColor(tween(previousR, r, i), tween(previousG, g, i), tween(previousB, b, i));
    }
}

function brightness(value){
    const activeLEDs = Math.round(pixels.length / (value * pixels.length));
    const previousR = rg
    const previousG = gg;
    const previousB = bg;
    brightnessG = value;

    for(let i = 0; i < pixels.length; i++){
        if(i % activeLEDs === 0){
            setColorForPixel(i, previousR, previousG, previousB, false);
        } else {
            setColorForPixel(i,0,0,0,false);
        }
    }
    ws281x.render(pixels);
}

function tweenToBrightness(value){
    const previousBrightness = brightnessG;
    let i = 0;
    while(i < 1){
        i += .1;
        brightness(tween(previousBrightness, value, i));
    }
}

function off(){
    setColor(0,0,0);
}

module.exports = {
    setColor,
    brightness,
    tweenToBrightness,
    setColorForPixel,
    tweenToColor,
    tween,
    init,
    off
};