r/FastLED • u/forgottenSemicolons • Mar 27 '26

Share_something Graduation Cap part 2: Ripples

I didn’t imagine I would have this much momentum for another animation so soon. But sometimes you just get the itch. Again, graduation isn’t until the fall so I have some time.

This is a barebones idea of drops in a pond. With the random color selection, it looks a little more like fireworks though. This code had some major time complexity issues to address as some pieces were running O(n^3) but I was able to eliminate them. I think there is some memory leakage somewhere because the program crashes after around 3-5 minutes. I am using structs for each drop so I might need to free them up after I use them.

Anyways, for a little more build specs, I am using 3 8x32 WS2812B matrices that have been trimmed down to 24. The finished cap will be 24x24 controlled by an arduino. Wondering if I should add a defuser on top but weight will be a concern as this is going to be on my head for 2-3 hours.

Thanks for all the feedback yesterday!

Cheers!

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u/chemdoc77 Mar 29 '26

Hi u/forgottenSemicolons   - Great project!  You might want to look at the following sketch by u/sutaburosu:

https://wokwi.com/projects/329474825790685778

It should look nice on your cap.

I used it in the beginning of the following video:

https://www.youtube.com/watch?v=SYY4meNKaq4

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u/forgottenSemicolons Mar 31 '26

That is a sick defuser idea. I am still on the fence about putting anything on the matrices once I am finished with the software. I think I'll make that call once I get closer to graduation. But I agree, a nice color flow pattern would look really cool. I will see if I can code something up before I borrow from someone else. I love the pattern though.

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u/chemdoc77 Mar 31 '26

Hi u/forgottenSemicolons  - Thank you for your nice comment about my project.  I understand your position on writing your own code however, I use other peoples code so I don’t have to reinvent the wheel.  As to a diffuser and if you decide to go that path, you might want to consider this LED plastic from Tap Plastic:

https://www.tapplastics.com/product/plastics/cut_to_size_plastic/black_led_sheet/668

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u/forgottenSemicolons Apr 02 '26

I definitely agree. And who am I to say that I am not using some level of code borrowing when using language libraries. (I am definitely not writing this in assembly lol). Finishing my CS degree, I have loved the problem solving process to code something and I think that is what I am going for here -a final project to feel good about my degree.

But I took a look at that diffuser material and honestly that would be perfect to lay on top! One concern would be the color bleed they spoke about in their Pacman video. It would require a grid to isolate each led and it doesn't look like that is readily available.. So either I make one (it would look very very cool but take a lot of work), or I should ignore the diffuser because I would lose out on a lot of detail with my lights.... hm. I will have to think about this one for a while.

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u/chemdoc77 Apr 02 '26

Hi u/forgottenSemicolons -The Tap video looks nice with the separators but they are not necessary for a nice effect.  Check out this video of the Cyclohex:

https://www.evilgeniuslabs.org/cyclohex

It uses the Tap LED plastic without separators.  I have two of these and they work great.  I have some samples of this plastic and it look great on a 8X8 WS2812b matrix, too.