// https://www.reddit.com/r/FastLED/comments/1glyqbu/i_cant_use_more_than_255_leds_on_my_strip_of_300/

#include <FastLED.h>

#define NUM_LEDS 300
#define LED_PIN 7

CRGB leds[NUM_LEDS];

uint8_t paletteIndex = 0;

DEFINE_GRADIENT_PALETTE (heatmap_gp) {
    0,   0,   0,   0, 
  128, 255,   0,   0,
  200, 255, 255,   0,
  255, 255, 255, 255,
};

CRGBPalette16 myPal = heatmap_gp;


void setup() {
  // put your setup code here, to run once:
  FastLED.addLeds<WS2812B, LED_PIN, GRB>(leds, NUM_LEDS);
  // FastLED.setBrightness(50);
}


template <typename PALETTE>
void fill_palette16(CRGB* L, uint16_t N, uint16_t startIndex, uint16_t incIndex,
                  const PALETTE& pal, uint8_t brightness=255, TBlendType blendType=LINEARBLEND)
{
    uint16_t colorIndex = startIndex;
    for( uint16_t i = 0; i < N; ++i) {
        L[i] = ColorFromPalette( pal, colorIndex >> 8, brightness, blendType);
        colorIndex += incIndex;
    }
}


void loop() {
  // put your main code here, to run repeatedly:
  fill_palette16(leds, NUM_LEDS, paletteIndex << 8, 65535 / NUM_LEDS, myPal, 255, LINEARBLEND);
  FastLED.show();
}