fire.js

/**
 * fire.js
 *
 * Fire by Mark Kriegsman, originally for the FastLED library
 *
 * see: https://github.com/FastLED/FastLED/blob/master/examples/Fire2012/Fire2012.ino
 *
 * LEDstrip plugin
 *
 * Copyright (c) 2013 Dougal Campbell
 *
 * Distributed under the MIT License
 */

function Fire (ledstrip, opts) {
	opts = opts || {};
	this.ledstrip = ledstrip;
	this.ledstrip.clear();

	this.NUM_LEDS = this.ledstrip.size();

	this.FRAMES_PER_SECOND = 60;

	this.COOLING = 55;
	this.SPARKING = 120;

	this.heat = new Array(this.NUM_LEDS);

	this.t = 0;										// tick counter

	return this;
}

Fire.prototype.init = function() {
	for (var i = 0, l = this.heat.length; i < l; i++) {
		this.heat[i] = 0;
	}

	return this;
}

// Get a timestamp for ms milliseconds from now
Fire.prototype.addTime = function (ms) {
	return (new Date()).valueOf() + ms;
}

// Replicate random8() function
Fire.prototype.random8 = function(min, max) {
	if (min === undefined) {
		min = 0;
		max = 255;
	}
	if (max === undefined) {
		max = min;
		min = 0;
	}
	return (Math.round(Math.random() * (max - min)) + min) & 255;
}

// Replicate random16() function
Fire.prototype.random16 = function(min, max) {
	if (min === undefined) {
		min = 0;
		max = 65535;
	}
	if (max === undefined) {
		max = min;
		min = 0;
	}
	return (Math.round(Math.random() * (max - min)) + min) & 65535;
}

Fire.prototype.qadd8 = function(a, b) {
	var tmp = Math.round(a + b);
	if (tmp > 255) tmp = 255;

	return tmp;
}

Fire.prototype.qsub8 = function(a, b) {
	var tmp = Math.round(a - b);
	if (tmp < 0) tmp = 0;

	return tmp;
}

Fire.prototype.scale8_video = function(val, min, max) {
	if (max === undefined) {
		max = min;
		min = 0;
	}

	return Math.floor(val * (max - min) / 255 + min);
}


Fire.prototype.millis = function() {
	return (new Date()).valueOf();
}

Fire.prototype.Fire2012 = function() {
  // Step 1.  Cool down every cell a little
    for( var i = 0; i < this.NUM_LEDS; i++) {
      this.heat[i] = this.qsub8( this.heat[i],  this.random8(0, Math.floor((this.COOLING * 10) / this.NUM_LEDS) + 2));
    }
 
    // Step 2.  Heat from each cell drifts 'up' and diffuses a little
    for( var k = this.NUM_LEDS - 3; k > 0; k--) {
      this.heat[k] = Math.floor((this.heat[k - 1] + this.heat[k - 2] + this.heat[k - 2] ) / 3) || 0;
    }
   
    // Step 3.  Randomly ignite new 'sparks' of heat near the bottom
    if( this.random8() < this.SPARKING ) {
      var y = this.random8(7);
      this.heat[y] = this.qadd8( this.heat[y], this.random8(160,255) );
    }
 
    // Step 4.  Map from heat cells to LED colors
    for( var j = 0; j < this.NUM_LEDS; j++) {
        this.ledstrip.buffer[j] = this.HeatColor( this.heat[j]);
    }
}

//Play with this for different strip colors
Fire.prototype.HeatColor = function(temperature) {
  var heatcolor = [0,0,0];
  if (temperature === undefined) {
  	temperature = 0;
  }
 
  // Scale 'heat' down from 0-255 to 0-191,
  // which can then be easily divided into three
  // equal 'thirds' of 64 units each.
  var t192 = this.scale8_video( temperature, 192);
 
  // calculate a value that ramps up from
  // zero to 255 in each 'third' of the scale.
  var heatramp = t192 & 0x3F; // 0..63
  heatramp <<= 2; // scale up to 0..252
 
  // now figure out which third of the spectrum we're in:
  if( t192 & 0x80) {
    // we're in the hottest third
    heatcolor[0] = 255; // full red
    heatcolor[1] = 255; // full green
    heatcolor[2] = heatramp; // ramp up blue
   
  } else if( t192 & 0x40 ) {
    // we're in the middle third
    heatcolor[0] = 255; // full red
    heatcolor[1] = heatramp; // ramp up green
    heatcolor[2] = 0; // no blue
   
  } else {
    // we're in the coolest third
    heatcolor[0] = heatramp; // ramp up red
    heatcolor[1] = 0; // no green
    heatcolor[2] = 0; // no blue
  }
 
  return heatcolor;
}


Fire.prototype.animate = function() {
	animation = requestAnimationFrame(this.animate.bind(this)); 	// preserve our context

	this.Fire2012();

	this.ledstrip.send(); // display the LED state

	this.t++; // increment tick
}