RPi SPI rainbow on Python

RPi-SPI-example.py

#!/usr/bin/python

# Light painting / POV demo for Raspberry Pi using
# Adafruit Digital Addressable RGB LED flex strip.
# ----> http://adafruit.com/products/306

import RPi.GPIO as GPIO, time, math

def fillStrip(strip, stripLength, gamma, t):
    for x in range(stripLength):
        
        r = int(math.sin((t+x)*0.05)*255)
        g = int(math.cos((t+x)*0.05)*255)
        b = int(math.cos((t+x+32)*0.05)*255)
        x3 = x * 3
        strip[x3]   = gamma[r]
        strip[x3+1] = gamma[g]
        strip[x3+2] = gamma[b]

# Configurable values
stripLength = 64

# Open SPI device, load image in RGB format and get dimensions:
dev       = "/dev/spidev0.0"
spidev    = file(dev, "wb")

gamma = bytearray(256)
for i in range(256):
    gamma[i] = 0x80 | int(pow(float(i) / 255.0, 2.5) * 127.0 + 0.5)

# Create list of bytearrays, one for each column of image.
# R, G, B byte per pixel, plus extra '0' byte at end for latch.
print "Allocating..."
strip = bytearray(stripLength*3 + 1)

# Then it's a trivial matter of writing each column to the SPI port.
print "Displaying..."
t = 0
while True:
    fillStrip(strip, stripLength, gamma, t)
    spidev.write(strip)
    spidev.flush()
    t += 1
    time.sleep(0.05)