76 lines
2.1 KiB
Python
76 lines
2.1 KiB
Python
import random
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import board
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import neopixel
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from _pixelbuf import wheel
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import ulab
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import ulab.filter
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# Customize your neopixel configuration here...
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pixel_pin = board.D5
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num_pixels = 96
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pixels = neopixel.NeoPixel(pixel_pin, num_pixels, brightness=0.1,
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auto_write=False, pixel_order=neopixel.RGB)
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ddt = ulab.array([1.,-2.,1.])
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def step(u, um, f, n, dx, dt, c):
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dt2 = dt*dt
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C2 = (c*dt/dx)**2
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deriv = ulab.filter.convolve(u, ddt)[1:-1] * C2
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up = -um + u * 2 + deriv + f * dt2
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up[0] = 0
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up[n-1] = 0
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return up
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def main():
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# This precomputes the color palette for maximum speed
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# You could change it to compute the color palette of your choice
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w = [wheel(i) for i in range(256)]
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# This sets up the initial wave as a smooth gradient
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u = ulab.zeros(num_pixels)
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um = ulab.zeros(num_pixels)
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f = ulab.zeros(num_pixels)
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slope = ulab.linspace(0, 256, num=num_pixels)
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th = 1
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# the first time is always random (is that a contradiction?)
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r = 0
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while True:
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# Some of the time, add a random new wave to the mix
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# increase .15 to add waves more often
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# decrease it to add waves less often
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if r < .01:
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ii = random.randrange(1, num_pixels-1)
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# increase 2 to make bigger waves
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f[ii] = (random.random() - .5) * 2
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# Here's where to change dx, dt, and c
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# try .2, .02, 2 for relaxed
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# try 1., .7, .2 for very busy / almost random
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u, um = step(u, um, f, num_pixels, .1, .02, 1), u
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v = u * 200000 + slope + th
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for i, vi in enumerate(v):
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# Scale up by an empirical value, rotate by th, and look up the color
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pixels[i] = w[round(vi) % 256]
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# Take away a portion of the energy of the waves so they don't get out
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# of control
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u = u * .99
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# incrementing th causes the wheel to slowly cycle even if nothing else is happening
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th = (th + .25) % 256
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pixels.show()
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# Clear out the old random value, if any
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f[ii] = 0
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# and get a new random value
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r = random.random()
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main()
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