Here is a simple arch that I built using FastLED.

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Here is a simple arch that I built using FastLED. It is a string of 50 12mm bullet style WS2811 pixels inside a piece of 1" diameter PEX tubing. The PEX makes for a nice diffuser and helps to protect the pixels from the elements. Special thanks to @Andrew_Tuline and @Mark_Kriegsman for sharing their code. I used the examples they have posted here as the basis for this project. https://www.youtube.com/watch?v=Z5yOy1H8WHg&feature=youtu.be

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Looks great! The PEX is indeed a nice diffuser. I’ll have to keep that in mind for future projects.

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Oh, very nice – I like when the diffuser is also structural like this.
Looks great!

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You used white PEX tubing, I take it? How much light does the tubing block (vs just diffusing)? I ask because depending on the wall thickness, it might have very different effects.

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Yes, white PEX. It does not block much light. The stuff is pretty translucent. I was able to buy a 20ft long straight “stick” of PEX at a plumbing supply company. If you buy it in a roll, it is almost impossible to straighten.

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I was about to ask where you got it! Plumbing supply sounds like a good lead. And did you have to grease the pixels to get them to slide in OK?

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Yes, I had to use some silicone spray to get them to slide into the PEX. It looks like they should fit with plenty of room left over, but when you pull on the wire, the bullet style pixels rotate and try to wedge themselves into the tube and press on the sides like little cams. You could probably use 3/4" PEX for a short run (3-4 ft) but for 15ft the 1" diameter was a must. A pixel strip would work great in the 3/4" PEX and 3/4" is really cheap at Home Depot ($5 for 10ft). The 1" PEX was $28 for 20ft at the plumbing supply.

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That’s awesome looking, especially with the diffuser.

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That looks great. Don’t think we can get anything like pex here, though :frowning:

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starting at 5 secs into the video, pixels start moving in 2 directions from the center. could anyone please explain how this done. what is the effect called? is there sample code anywhere?

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I don’t think that’s math, I think it’s just code. :slight_smile:

Remember that the pixels never actually move. Instead, you’re applying more light to some, and less light to others, and it gives the illusion of motion.

So: you want to apply light to two places: one that moves a little left each frame and on that moves a little right each frame. If they’re mirror reflections of each other, that means:

secondLightPos = NUM_LEDS - firstLightPos

Try it (by hand) with a few numbers, and you see what’s going on there.

I bet you could easily adapt any of the “Cylon” sketches to have two mirrored lights using this technique. Anyone want to volunteer a few lines of code to help a learner out?

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Mark is right. Here is the code for that effect.

void rainbow_march_drop() {
if (thisdir == 0) thishue += thisrot; else thishue-= thisrot;
fill_rainbow(leds, NUM_LEDS, thishue, deltahue);

if (cylon_number < NUM_LEDS/2){
leds[cylon_number] = CRGB::White;
leds[NUM_LEDS - cylon_number - 1] = CRGB::White;
}

if (cylon_number <= 0) {
cylon_number = (NUM_LEDS/2) + 30; //Change this value to control the delay of the raindrops
}
else {
cylon_number = cylon_number -1;
}

}

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thanks I got it. It was the mention of mirroring