commit 1c6518aa13851b72132d7c03e21af109b68f6134
Author: Daniel Barber <github@danbarber.me>
Date:   Fri Dec 15 16:03:07 2017 +0000

    Can't believe I never put this in git

diff --git a/fire.py b/fire.py
new file mode 100644
index 0000000..b114cfb
--- /dev/null
+++ b/fire.py
@@ -0,0 +1,100 @@
+from random import randint
+import unicornhat as unicorn
+from time import sleep
+
+width = 8
+height = 8
+rows = []
+row_pointer = 0
+
+colours = []
+
+unicorn.brightness(0.4)
+unicorn.rotation(270)
+
+
+def init():
+
+    global rows
+
+    # create a buffer of <height> blank rows
+    for i in range(height):
+        rows.append(get_blank_row())
+
+    # add an initial source row
+    rows.append(get_source_row())
+
+    # generate an array of colours
+    for i in range(64):
+        r = i * 4
+        g = 0 
+        b = 0
+        if i > 24:
+            g = (i - 24) * 6
+        if i > 48:
+            g = (i - 48) * 8
+        colours.append([r, g, b])
+
+
+def get_blank_row():
+
+    # generate a blank row
+    return [0] * (width + 2)
+
+
+def get_source_row():
+
+    # generate a source row with random white
+    new_row = []
+    for i in range(width + 2):
+        new_row.append(randint(0, 63))
+    return new_row
+
+
+def update_rows():
+
+    # create fire
+    for h in range(height):
+        for w in range(width):
+            rows[h][w + 1] = (rows[h + 1][w] + rows[h + 1][w + 1] + rows[h + 1][w + 2]) / 3.4
+
+
+def update_display():
+
+    # keep track of the row we are updating
+    for h in range(height):
+        for w in range(width):
+            # val is between 50 and 255
+            val = rows[h][w + 1]
+
+            # fetch the colour
+            colour = colours[int(round(val))]
+
+            # invert coordinates
+            unicorn.set_pixel((width - 1) - w, (height - 1) - h, colour[0], colour[1], colour[2])
+
+    unicorn.show()
+
+
+def step():
+    global row_pointer
+
+    # add new row at current row pointer
+    # leave other rows the same, display will start from this one which overwrites the
+    # oldest existing row from the last time we updated the display
+    update_rows()
+    update_display()
+
+    if row_pointer % 2 == 0:
+        rows[height] = get_source_row()
+
+    # determine next row pointer, wrapping around if we went past zero
+    row_pointer -= 1
+    if row_pointer < 0:
+        row_pointer = height - 1
+
+
+init()
+while True:
+    step()
+    sleep(0.05)