leds/lights.js

import ws281x from 'rpi-ws281x'
import * as fs from 'fs'

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

const fade_ticks = cfg.fade_ticks || 20;
var pixels = new Uint32Array(cfg.leds);
var pixel_cache = new Uint32Array(cfg.leds);
var next_pattern = new Uint32Array(cfg.leds);
var pattern = {}

function rgb_to_int(r, g, b) {
  return ((r << 8) + g) << 8 + b;
}
function int_to_rgb(int) {
  var r = int >> 16 & 0xFF;
  var g = int >> 8 & 0xFF;
  var b = int & 0xFF;
  return { r: r, g: g, b: b };
}

ws281x.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
  console.log("TICKING PATTERN")

  for (let i = 0; i < cfg.leds; i++) {
    var r = Math.floor(Math.random() * 100)
    var g = Math.floor(Math.random() * 100);
    var b = Math.floor(Math.random() * 100);
    next_pattern[i] = ((r << 8) + g) << 8 + b;
  }
}

export function tick() {
  var changed = false;
  for (let i = 0; i < cfg.leds; i++) {
    if (next_pattern[i] != pixels[i]) {
      if (next_pattern[i] == pixel_cache[i]) {
        console.log("INCONGRUENCE WITH " + i);
        pixels[i] = next_pattern[i]
      }
      else {
        changed = true;
        fade(i);
      }
    }
  }
  if (!changed) {
    tick_pattern();
  }
  ws281x.render(pixels);
  ws281x.sleep(cfg.sleep_time || 500);
}

function fade(index) {
  var original = int_to_rgb(pixel_cache[index]);
  var current = int_to_rgb(pixels[index]);
  var final = int_to_rgb(next_pattern[index]);
  var diff_r = final.r - original.r;
  var diff_cr = current.r - original.r;
  var diff_g = final.g - original.g;
  var diff_b = final.b - original.b;
  var interval_r = diff_r / fade_ticks;
  var interval_g = diff_g / fade_ticks;
  var interval_b = diff_b / fade_ticks;

  var current_tick = Math.floor((diff_cr / diff_r) * fade_ticks);

  if (diff_r == 0) {
    current_tick = fade_ticks;
  }
  // console.log(`original: ${original.r} ${original.g} ${original.b}\n` +
  //   `current:  ${current.r} ${current.g} ${current.b}\n` +
  //   `final:  ${final.r} ${final.g} ${final.b}\n` +
  //   `interval:  ${interval_r} ${interval_g} ${interval_b}\n`)

  if (current_tick + 1 >= fade_ticks) {
    pixels[index] = next_pattern[index];
    pixel_cache[index] = next_pattern[index];
  }
  else {
    pixels[index] = rgb_to_int(current.r + interval_r,
      current.g + interval_g,
      current.b + interval_b);
  }
}