/// @file    Moire.ino
/// @brief   Moiré interference patterns 2D effect
/// @example Moire.ino
/// @author  sutaburosu

#include <Arduino.h>
#include <FastLED.h>

using namespace fl;

#define HEIGHT 16
#define WIDTH 16
#define NUM_LEDS ((WIDTH) * (HEIGHT))
#define IS_SERPENTINE true

XYMap xyMap(WIDTH, HEIGHT, IS_SERPENTINE);
UITitle title("Moiré");
UIDescription description("Shows a Moiré interference pattern.");
UICheckbox checkboxA("A hypot() or atan2()", true );
UICheckbox checkboxB("B hypot() or atan2()");
UISlider speed("Speed", 3.0f, 0.25f, 20.0f);
UISlider scale("Scale", 1.0f, 0.25f, 10.0f);
UISlider scaleA("Scale A", 3.0f, 1.0f, 16.0f);
UISlider scaleB("Scale B", 3.0f, 1.0f, 16.0f);

CRGB leds[NUM_LEDS];
CRGBPalette16 palette = RainbowColors_p;

void setup()
{
  Serial.begin(115200);
  FastLED.addLeds<NEOPIXEL, 25>(leds, NUM_LEDS).setScreenMap(xyMap);
}

void loop()
{
  struct vec2
  {
    float x;
    float y;
  };

  // Render a moire pattern
  static uint32_t ms = 0;
  static float t = 0.0f;
  uint32_t newms = millis();
  t += (newms - ms) * 0.00005f * float(speed);
  ms = newms;

  const float m = min(WIDTH, HEIGHT) * float(scale);
  const vec2 centreA = {
    cosf(t * 3.0f) * 0.5f,
    sinf(t * 7.0f) * 0.5f
  };
  const vec2 centreB = {
    cosf(t * 5.0f) * 0.5f,
    sinf(t * 4.0f) * 0.5f
  };

  for (int y = 0; y < HEIGHT; y++)
  {
    for (int x = 0; x < WIDTH; x++)
    {
      vec2 coord = {2.0f * (x - WIDTH / 2.0f) / m,
                    2.0f * (y - HEIGHT / 2.0f) / m
                   };

      float A, B;
      if (checkboxA)
        A = atan2f(centreA.x - coord.x, centreA.y - coord.y) + t * 1.01f;
      else
        A = hypotf(centreA.x - coord.x, centreA.y - coord.y);
      if (checkboxB)
        B = atan2f(centreB.x - coord.x, centreB.y - coord.y) - t * 1.37f;
      else
        B = hypotf(centreB.x - coord.x, centreB.y - coord.y);

      float aMod = 6.282f + (cosf(t * 2.12f) * 0.5f + 0.5f) * float(scaleA);
      float bMod = 6.282f + (cosf(t * 3.33f) * 0.5f + 0.5f) * float(scaleB);

      float a = cosf(A * aMod);
      float b = cosf(B * bMod);

      float i = ((a * b) + 1.0f) / 2.0f; // mult
      float j = ((a + b) + 2.0f) / 4.0f; // sum

      uint16_t valuei16 = uint16_t(i * 65535.0f) + uint16_t(t * 256.f * 300.f);
      uint8_t valuej8 = uint8_t(j * 240.0f) + 15;
      uint32_t idx = xyMap.mapToIndex(x, y);
      leds[idx] = ColorFromPaletteExtended(palette, valuei16, valuej8, LINEARBLEND);
    }
  }

  FastLED.show();

  if (1) { // show frame timings
    static uint64_t fps_us;
    static uint16_t frame;
    if (++frame == 100) {
      uint64_t time_us = micros() - fps_us;
      Serial.print(time_us / float(frame));
      Serial.print("us\t");
      Serial.print(frame * 1000000.f / time_us, 3);
      Serial.println("FPS");
      fps_us = micros();
      frame = 0;
    }
  }

}