leds/lights.js

import { Module } from 'rpi-ws281x'
import * as fs from 'fs'

const cfg = JSON.parse(fs.readFileSync('./config.json'));

const fade_ticks = cfg.fade_ticks || 10;
var pixels = new Uint32Array(cfg.leds);
var pixel_cache = new Uint32Array(cfg.leds);
var next_pattern = new Uint32Array(cfg.leds);
var pattern = {}

Module.configure({
  leds: cfg.leds || 300,
  brightness: cfg.brightness || 200,
  gpio: cfg.gpio || 18,
  stripType: cfg.type || 'grb'
});

export function set_pattern(pat) {
  pattern = pat
}

function tick_pattern() {
  // do the parsing stuff here
  var r = Math.floor(Math.random() * 100)
  var g = Math.floor(Math.random() * 100);
  var b = Math.floor(Math.random() * 100);

  for (let i = 0; i < cfg.leds; i++) {
    if (i % 3 == 0) {
      next_pattern[i] = r;
      next_pattern[i + 1] = g;
      next_pattern[i + 2] = b;
    }
  }
}

export function tick() {
  var changed = false;
  for (let i = 0; i < cfg.leds; i++) {
    if (next_pattern[i] != pixels[i]) {
      changed = true;
      fade(i);
    }
  }
  if (!changed) {
    tick_pattern();
  }
  Module.render(pixels);
}

function fade(index) {
  var original = pixel_cache[index];
  var final = next_pattern[index];
  var diff = final - original;
  var interval = diff / fade_ticks;

  if (Math.abs(final - pixels[index]) < interval) {
    pixels[index] = final;
    pixel_cache[index] = final;
  }
  else {
    pixels[index] += interval;
  }
}