Looking to have a circular fade rotating at a specific speed of degrees per second.

RingAnimationDebug.ino

/*
 * Speed up the rotation of LEDs lights or slow down based on button press
 */

#include "blinklib.h"
#include "Serial.h"

ServicePortSerial Serial;

float rotation = 0;
uint16_t speed = 360; // speed is represented in degrees/sec, 360 would be a single rotation per second
uint32_t timeOfLastLoop = 0;

void setup() {
  // put your setup code here, to run once:
  // No setup needed for this simple example!  
  Serial.begin(); 

  Serial.println("Ring Animation Debug");  

}

void loop() {
  // put your main code here, to run repeatedly:
  uint32_t timeDiff = millis() - timeOfLastLoop;
  if(timeDiff >= 1) {
    setColor( OFF );
  
    // calculate the amount of rotation
    rotation += (timeDiff * speed) / 1000.f;
    if(rotation >= 360.f) {
      rotation -= 360.f;
    }
    
    FOREACH_FACE(f) {
      // determine brightness based on the unit circle (sinusoidal fade)
      int brightness = int(255.f * (1 + sin(((30.f * f) + rotation)/180.f))/2.f);
      setFaceColor( f , makeColorHSB(0,0,brightness));

//      if(f==4) {
//        Serial.print("rotation: ");
//        Serial.println(rotation);
//        Serial.print("brightness: ");
//        Serial.println(brightness);
//      }
    }  
  
    timeOfLastLoop = millis();
  }
}