cylon.py

#!/usr/bin/env python

# Display "Cylon" style bouncing red light

import colorsys
import time
import numpy as np

text_mode = False

try:
    import blinkt
except ImportError:
    print("No blinkt package; switching to text mode.")
    text_mode = True

from sys import exit, stdout

# This way we can test things out on laptop
if text_mode:
    counter = 0
    direction = 1
    width = 8
    while True:
        counter = counter + direction

        if counter > width - 1:
            direction = -1
        elif counter < 1:
            direction = 1

        output = ""
        for x in range(0, counter):
            output = output + "-"
        output = output + "X"
        for x in range(counter, width):
            output = output + "-"
        output = output + '\r'
        stdout.write(output)
        stdout.flush()
        time.sleep(0.1)

blinkt.set_clear_on_exit()

position = 0.0
speed_scale = 7
time_step = 0.05
thickness = 0.06

direction = 1
t = 0.01
while True:
    start = time.time()
    
    position = position + (direction * (speed_scale * t))
    if position > 1:
        direction = -1
    elif position < 0:
        direction = 1
    # print("Position: ", position)
        
    for index in range(0, blinkt.NUM_PIXELS):
        # for each LED calculate distance from current position
        location = index / float(blinkt.NUM_PIXELS - 1)
        distance = abs(location - position)
        # print("Location: ", location, " Distance: ", distance)
        # calculate intensity based on distance
        r = np.exp(-np.power(distance, 2.0) / (2 * np.power(thickness, 2.0)))
        r = r * 255
        # print("Set pixel ", index, " to ", r)
        blinkt.set_pixel(index, r, 0, 0)

    blinkt.show()


    end = time.time()
    t = end - start

    if t < time_step:
        time.sleep(time_step - t)