Tested with the Adafruit NeoPixel LED strip.

Based on the algorithm from http:https://pastebin.com/xYEpxqgq

Wire the NeoPixel LEDs to the Raspberry Pi as desired. Right now it expects the NeoPixel DIN to be connected to GPIO pin 18.

pip install git+https://github.com/willbarton/neopixelflames
sudo neopixelflames

You should then see a red-ish "heat" glow with occasional yellow/white "sparking" that affects adjacent pixels.

You can specify a JSON configuration file, if you want to change the defaults:

sudo neopixelflames -c config.json

The config values of interest are:

• num_pixel: the number of pixels available
• sparking: The chance (out of 255) that a new spark will be lit each iteration
• cooling: How much does the fire cools (out of 100) with each iteration
• colors: RGB values listed from coolest color to hottest color
• levels: RGB color balance

Some ideas:

• Default, cool embers:

  {
      "num_pixels": 60,
      "sparking": 100,
      "cooling": 50,
      "colors": [
          [0.75, 0.0, 0.2],
          [1.0, 0.0, 0.0],
          [1.0, 0.5, 0.0],
          [1.0, 0.7, 0.2],
          [1.0, 0.9, 0.9]
      ],
      "levels": [0.9, 1.0, 0.15]
  }

• Goblet of fire:

  {
      "num_pixels": 60,
      "sparking": 100,
      "cooling": 50,
      "colors": [
          [0.2, 0.34, 0.83],
          [0.36, 0.52, 0.95],
          [0.5, 0.85, 0.98],
          [0.73, 0.97, 0.98],
          [0.9, 0.9, 1.0]
      ],
      "levels": [0.9, 1.0, 0.15]
  }

• 'Merica:

  {
      "num_pixels": 60,
      "sparking": 100,
      "cooling": 50,
      "colors": [
          [0.0, 0.0, 0.98],
          [1.0, 0.0, 0.09],
          [1.0, 1.0, 1.0],
      ],
      "levels": [0.9, 1.0, 0.15]
  }

• Pride:

  {
      "num_pixels": 60,
      "sparking": 100,
      "cooling": 50,
      "colors": [
          [0.52, 0.0, 0.49],
          [0.0, 0.0, 0.98],
          [0.0, 0.5, 0.09],
          [1.0, 1.0, 0.25],
          [1.0, 0.65, 0.17],
          [1.0, 0.0, 0.09]
      ],
      "levels": [0.9, 1.0, 0.15]
  }