#include <FastLED.h>

#define LED_PIN  3
#define COLOR_ORDER       GRB
#define CHIPSET           WS2812B
#define pWIDTH      24
#define pHEIGHT     24
#define NUM_LEDS          ((pWIDTH) * (pHEIGHT))
#define pHalfWidth        (pWIDTH / 2)
#define pHalfHeight       (pHEIGHT / 2)

CRGB leds[NUM_LEDS];

struct {
  float angle;
  float radius;
}
rfMap[pWIDTH][pHEIGHT];

uint16_t getPixelNumber(uint8_t x, uint8_t y) {
  if (x >= pWIDTH || y >= pHEIGHT)
    return NUM_LEDS;
  if (y & 1)
    x = pWIDTH - 1 - x;
   return x + (y * pWIDTH);
}

uint16_t XY(uint8_t x, uint8_t y) {
  return getPixelNumber(x, y);
}

void setup() {
  FastLED.addLeds<CHIPSET, LED_PIN, COLOR_ORDER>(leds, NUM_LEDS).setCorrection(UncorrectedColor);
  for (int8_t x = -pHalfWidth; x < pHalfWidth; x++) {
    for (int8_t y = -pHalfHeight; y < pHalfHeight; y++) {
      rfMap[x + pHalfWidth][y + pHalfHeight].angle = atan2(y, x) * (360. / 2. / PI) * pHalfWidth;
      rfMap[x + pHalfWidth][y + pHalfHeight].radius = hypotf(y, x);
    }
  }
}


void loop() {
  drawFrame();
  FastLED.show();
}

void drawFrame() {
  uint8_t effectBrightness = 255;
  static byte scale = 100; // slider 1 ... 100
  static byte speed = 48; // slider 8 ... 64
  static uint32_t t;
  t += speed;
  fadeToBlackBy(leds, NUM_LEDS, 5);
  for (uint8_t x = 0; x < pWIDTH; x++) {
    for (uint8_t y = 0; y < pHEIGHT; y++) {
      float angle = rfMap[x][y].angle;
      float radius = rfMap[x][y].radius;
      int16_t Bri = inoise8(angle, radius * scale - t) - radius * pHEIGHT/4;
      if (Bri < 0) Bri = 0; if(Bri != 0) Bri = 256 - (Bri * .4);
      int16_t Col = inoise8(angle, radius * scale - t) - radius * pHEIGHT/4;
      if (Col < 0) Col = 0;
      int16_t idx = XY(x, y);
      if (idx >= 0 && idx < NUM_LEDS) nblend(leds[idx], ColorFromPalette(HeatColors_p, Col, map8(Bri,0,effectBrightness)), speed);
    }
  }
}