# Tiny adjustment to spot or wide color picker: Toroid/wrap around **URL:** \ **Category:** Patterns and Code\ **Created:** [October 26, 2021, 9:01pm UTC](https://forum.electromage.com/t/tiny-adjustment-to-spot-or-wide-color-picker-toroid-wrap-around/1681 "2021-10-26T21:01:47Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![danner](https://forum.electromage.com/user_avatar/forum.electromage.com/danner/32/1607_2.png) [@danner](https://forum.electromage.com/u/danner)\ **Post date:** [October 26, 2021, 9:01pm UTC](https://forum.electromage.com/t/tiny-adjustment-to-spot-or-wide-color-picker-toroid-wrap-around/1681/1 "2021-10-26T21:01:47Z")
It’s a little fix for my room where the lights wrap around the ceiling, but the spot stops abruptly at the beginning or end of the pixel array. It’s got a fancy name at least, toroidal distance measurement! ```auto export function render(index) { distance = abs(location - index/pixelCount) if (distance > 0.5){ distance = 1.0 - distance } var v = value * pow(1 - distance, sharpness) hsv(hue, saturation, v) } ``` ---
**Author:** ![Scruffynerf](https://forum.electromage.com/letter_avatar_proxy/v4/letter/s/34f0e0/32.png) [@Scruffynerf](https://forum.electromage.com/u/Scruffynerf)\ **Post date:** [October 26, 2021, 11:46pm UTC](https://forum.electromage.com/t/tiny-adjustment-to-spot-or-wide-color-picker-toroid-wrap-around/1681/2 "2021-10-26T23:46:17Z")
I had to look up what you meant. In plain English: When dealing with circles (or closed loops, or donuts or…), this avoids the start or end of the led strand from being an edge/end and calculates the distance as if it wasn’t… It finds the shortest distance between two points, when there is more than one direction you could go. Better: > **[Calculating the Distance Between Points in “Wrap Around” (Toroidal) Space](https://blog.demofox.org/2017/10/01/calculating-the-distance-between-points-in-wrap-around-toroidal-space/)** > > Let’s say you are trying to find the distance between two points in 2D, but that these points are in a universe that “wraps around” like old video games – leaving the screen… Very helpful. Thanks! ---
**Author:** ![wizard](https://forum.electromage.com/user_avatar/forum.electromage.com/wizard/32/4_2.png) [@wizard](https://forum.electromage.com/u/wizard)\ **Post date:** [October 27, 2021, 12:31am UTC](https://forum.electromage.com/t/tiny-adjustment-to-spot-or-wide-color-picker-toroid-wrap-around/1681/3 "2021-10-27T00:31:08Z")
Thats very close to what `triangle()` does. ---
**Author:** ![Scruffynerf](https://forum.electromage.com/letter_avatar_proxy/v4/letter/s/34f0e0/32.png) [@Scruffynerf](https://forum.electromage.com/u/Scruffynerf)\ **Post date:** [October 27, 2021, 12:39am UTC](https://forum.electromage.com/t/tiny-adjustment-to-spot-or-wide-color-picker-toroid-wrap-around/1681/4 "2021-10-27T00:39:47Z")
Oooh, that’s a well hidden fact. So let’s see… `time()` cycles from 0 to 1 and repeats. A sawtooth: `/////` `triangle()` takes that cycle and converts it from a sawtooth into a triangular wave: `/\/\/\/\` ---
**Author:** ![danner](https://forum.electromage.com/user_avatar/forum.electromage.com/danner/32/1607_2.png) [@danner](https://forum.electromage.com/u/danner)\ **Post date:** [October 27, 2021, 12:39am UTC](https://forum.electromage.com/t/tiny-adjustment-to-spot-or-wide-color-picker-toroid-wrap-around/1681/5 "2021-10-27T00:39:51Z")
oh cool! This is my first time coding for pixelblaze, I’ll play around with `triangle()` - not that this pattern needs to be performant, but are there speed differences that mean I should use internal functions vs doing it myself? ---
**Author:** ![jeff](https://forum.electromage.com/user_avatar/forum.electromage.com/jeff/32/3473_2.png) [@jeff](https://forum.electromage.com/u/jeff)\ **Post date:** [October 27, 2021, 5:14am UTC](https://forum.electromage.com/t/tiny-adjustment-to-spot-or-wide-color-picker-toroid-wrap-around/1681/6 "2021-10-27T05:14:29Z")
> [@danner](#): > > are there speed differences that mean I should use internal functions vs doing it myself? Almost always! It’s one reason we commonly request new functions. 😉 ---
**Author:** ![danner](https://forum.electromage.com/user_avatar/forum.electromage.com/danner/32/1607_2.png) [@danner](https://forum.electromage.com/u/danner)\ **Post date:** [October 27, 2021, 12:52pm UTC](https://forum.electromage.com/t/tiny-adjustment-to-spot-or-wide-color-picker-toroid-wrap-around/1681/7 "2021-10-27T12:52:53Z")
alas, I couldn’t figure out a way to use `triangle()` to make this wrap around behavior. I think it’s possible, somehow stretching the triangle, but I couldn’t think of it last night, so it’ll stay with the if statement for now. ---
**Author:** ![Scruffynerf](https://forum.electromage.com/letter_avatar_proxy/v4/letter/s/34f0e0/32.png) [@Scruffynerf](https://forum.electromage.com/u/Scruffynerf)\ **Post date:** [October 27, 2021, 2:03pm UTC](https://forum.electromage.com/t/tiny-adjustment-to-spot-or-wide-color-picker-toroid-wrap-around/1681/8 "2021-10-27T14:03:18Z")
Yeah, I racked my brain to convert your code to it. I believe (and hopefully @wizard will correct me if I’m wrong) `triangle()` will (in essence) convert 0-0.5 values to 0-1 (effectively multiply by 2), and convert .5-1 values to 1-0 (= 2 - value x2) Your code says “if distance is greater than .5, distance is equal to 1 - distance” so you’re have to divide triangle(distance) by two to get your desired result. Replacement code: ```auto distance = triangle(abs(location - index/pixelCount))/2 ``` Should be slightly faster, but also far less casually understandable. ---
**Author:** ![danner](https://forum.electromage.com/user_avatar/forum.electromage.com/danner/32/1607_2.png) [@danner](https://forum.electromage.com/u/danner)\ **Post date:** [October 27, 2021, 2:22pm UTC](https://forum.electromage.com/t/tiny-adjustment-to-spot-or-wide-color-picker-toroid-wrap-around/1681/9 "2021-10-27T14:22:27Z")
thanks! thus begins the descent into madness. ---
**Author:** ![wizard](https://forum.electromage.com/user_avatar/forum.electromage.com/wizard/32/4_2.png) [@wizard](https://forum.electromage.com/u/wizard)\ **Post date:** [October 27, 2021, 6:49pm UTC](https://forum.electromage.com/t/tiny-adjustment-to-spot-or-wide-color-picker-toroid-wrap-around/1681/10 "2021-10-27T18:49:21Z")
@danner your version is great! I didn’t mean that as a criticism, I think its awesome that you figured out how to get the effect you were looking for! I wanted to share that triangle does that same kind of thing – ramps up, then back down (just scaled to 0-1) – in case it comes in handy for you later. I use that kind of thing so often it became one of the original Pixelblaze animation tools / APIs. You can see a similar thing in “fast pulse,” which will wrap, the core if that pattern (for 1D) is this: ```auto v = triangle(2 * wave(t1) + index / pixelCount) ``` The base structure of the triangle is `triangle(index/pixelCount)` which would start low, go high toward the middle, and back down. It animates that back and forth by adding this offset: `2 * wave(t1)`, which is like changing the spotlight’s position with a slider but animates based on the `t1` timer. The `* 2` causes to to spin twice over before returning, and `triangle()` wraps values to the 0-1 range so you can keep adding in components.