//source: https://editor.soulmatelights.com/gallery/250-flower

#include "FastLED.h"
#define DATA_PIN 2
#define BRIGHTNESS 255
#define NUM_LEDS 256
#define NUM_COLS 16
#define NUM_ROWS 16
#define LED_TYPE    WS2812B
#define COLOR_ORDER GRB
CRGB leds[NUM_LEDS];
//#define FRAMES_PER_SECOND 60
const uint8_t kMatrixWidth = 16;
const uint8_t kMatrixHeight = 16;

const bool    kMatrixSerpentineLayout = false;

float c = 0.3;   //diameter 
float angle = 0.1;
int  counter = 0;

void setup() {
  FastLED.addLeds<LED_TYPE,DATA_PIN,COLOR_ORDER>(leds, NUM_LEDS); //setCorrection(TypicalLEDStrip);
  //FastLED.addLeds<LED_TYPE,DATA_PIN,CLK_PIN,COLOR_ORDER>(leds, NUM_LEDS).setCorrection(TypicalLEDStrip);
  FastLED.setBrightness(BRIGHTNESS);
 //Serial.begin(115200);
}

void loop() 
{
  EVERY_N_MILLISECONDS(4000) {
    angle +=0.1;
  }
  
float n = triwave8( counter)*2.2;
    float a = n * angle;
    float r = c * sqrt16(n);
    byte x = r * cos(a)+NUM_COLS/2;
    byte y = r * sin(a)+NUM_ROWS/2;
   leds [XY(x,y)] += CHSV (millis(),255,BRIGHTNESS);
        counter +=1; 
   fadeToBlackBy(leds, NUM_LEDS, 10); //20
//blur2d(leds,NUM_COLS, NUM_ROWS, 8 );
      FastLED.show();

}
 
uint16_t XY( uint8_t x, uint8_t y)
{
  uint16_t i;
  if( kMatrixSerpentineLayout == false) {
    i = (y * kMatrixWidth) + x;
  }
  if( kMatrixSerpentineLayout == true) {
    if( y & 0x01) {
      // Odd rows run backwards
      uint8_t reverseX = (kMatrixWidth - 1) - x;
      i = (y * kMatrixWidth) + reverseX;
    } else {
      // Even rows run forwards
      i = (y * kMatrixWidth) + x;
    }
  }
  return i;
}