st-anything/lib/NeoPixelBus_by_Makuna/examples/animations/NeoPixelRotateLoop/NeoPixelRotateLoop.ino

// NeoPixelFunLoop
// This example will move a trail of light around a series of pixels.  
// A ring formation of pixels looks best.  
// The trail will have a slowly fading tail.
// 
// This will demonstrate the use of the RotateRight method.
//

#include <NeoPixelBus.h>
#include <NeoPixelAnimator.h>


const uint16_t PixelCount = 16; // make sure to set this to the number of pixels in your strip
const uint16_t PixelPin = 2;  // make sure to set this to the correct pin, ignored for Esp8266
const uint16_t AnimCount = 1; // we only need one
const uint16_t TailLength = 6; // length of the tail, must be shorter than PixelCount
const float MaxLightness = 0.4f; // max lightness at the head of the tail (0.5f is full bright)

NeoGamma<NeoGammaTableMethod> colorGamma; // for any fade animations, best to correct gamma

NeoPixelBus<NeoGrbFeature, Neo800KbpsMethod> strip(PixelCount, PixelPin);
// for esp8266 omit the pin
//NeoPixelBus<NeoGrbFeature, Neo800KbpsMethod> strip(PixelCount);

NeoPixelAnimator animations(AnimCount); // NeoPixel animation management object

void SetRandomSeed()
{
    uint32_t seed;

    // random works best with a seed that can use 31 bits
    // analogRead on a unconnected pin tends toward less than four bits
    seed = analogRead(0);
    delay(1);

    for (int shifts = 3; shifts < 31; shifts += 3)
    {
        seed ^= analogRead(0) << shifts;
        delay(1);
    }

    // Serial.println(seed);
    randomSeed(seed);
}

void LoopAnimUpdate(const AnimationParam& param)
{
    // wait for this animation to complete,
    // we are using it as a timer of sorts
    if (param.state == AnimationState_Completed)
    {
        // done, time to restart this position tracking animation/timer
        animations.RestartAnimation(param.index);

        // rotate the complete strip one pixel to the right on every update
        strip.RotateRight(1);
    }
}

void DrawTailPixels()
{
    // using Hsl as it makes it easy to pick from similiar saturated colors
    float hue = random(360) / 360.0f;
    for (uint16_t index = 0; index < strip.PixelCount() && index <= TailLength; index++)
    {
        float lightness = index * MaxLightness / TailLength;
        RgbColor color = HslColor(hue, 1.0f, lightness);

        strip.SetPixelColor(index, colorGamma.Correct(color));
    }
}

void setup()
{
    strip.Begin();
    strip.Show();

    SetRandomSeed();

    // Draw the tail that will be rotated through all the rest of the pixels
    DrawTailPixels();

    // we use the index 0 animation to time how often we rotate all the pixels
    animations.StartAnimation(0, 66, LoopAnimUpdate); 
}


void loop()
{
    // this is all that is needed to keep it running
    // and avoiding using delay() is always a good thing for
    // any timing related routines
    animations.UpdateAnimations();
    strip.Show();
}