testSinus

uint16_t getSinValue()
{
  uint16_t w16 = (millis() * 5) % 65536 ;
  return sin16(w16) + 32768 ;
}

void testAntiAliasedSinus()
{
  fillAll(getBackgroundColor(4)) ;
  antiAliasedSinusHelper(ledsExt, NUM_LEDS_EXT) ;
  antiAliasedSinusHelper(ledsMil, NUM_LEDS_MIL) ;
  antiAliasedSinusHelper(ledsInt, NUM_LEDS_INT) ;
  FastLED.show() ;
}

void antiAliasedSinusHelper(CRGB* heart, int nbPixels)
{
  int width = nbPixels / 14 ;
  int pixelGauche = get16PixelPosition(nbPixels / 2, width) ;
  int pixelDroit = nbPixels * 16 - pixelGauche - 16 * width;
  drawFractionalBar(heart, pixelGauche, width) ;
  drawFractionalBar(heart, pixelDroit, width) ;
}

int get16PixelPosition(int nbPixels, int width)
{
  return getSinValue() * (nbPixels * 16 - 16 * width) / 65536;
}

void drawFractionalBar(CRGB* heart, int pos16, int width )
{
  int i = pos16 / 16;
  uint8_t frac = pos16 & 0x0F;
  uint8_t firstpixelbrightness = 255 - (frac * 16);
  uint8_t lastpixelbrightness  = 255 - firstpixelbrightness;
  uint8_t bright;
  for( int n = 0; n <= width; n++) {
    if( n == 0 ) {
      // first pixel in the bar
      bright = firstpixelbrightness;
    } else if( n == width ) {
      // last pixel in the bar
      bright = lastpixelbrightness;
    } else {
      // middle pixels
      bright = 255;
    }

    heart[i] += CHSV( 0, 0, bright);
    i++;
  }
}