// Randomly assigns colors to blocks of pixels.
//
// Marc Miller,  Feb 2021
//---------------------------------------------------------------


#include <FastLED.h>

#define NUM_BLOCKS 6  // number of blocks
#define PPB 5  // pixels per block
#define NUM_LEDS NUM_BLOCKS * PPB  // 30
CRGB leds[NUM_LEDS];
uint8_t hue, sat;

void setup() {
  FastLED.addLeds<NEOPIXEL, 13>(leds, NUM_LEDS);

  // Initailly give all blocks a color
  for(int x = 0; x < NUM_BLOCKS; x++) {
    hue = random8();
    sat = random8(150,255);
    for(int i = 0; i < PPB; i++) {
      leds[(x * PPB) + i] = CHSV(hue, sat, 255);
    }
  }
}


void loop() {
  EVERY_N_MILLISECONDS(500) {
    uint8_t r = random8(3);  // how many blocks to update at the same time
    for(uint8_t x = 0; x < r; x++){
      uint8_t block = random8(NUM_BLOCKS);  // pick which block to update
    hue = random8();
    sat = random8(150,255);
      for(int i = 0; i < PPB; i++) {
        leds[(block * PPB) + i] = CHSV(hue, sat, 255);
      }
    }
  }
  FastLED.show();
}