//all possible colors NES should show
//https://en.wikipedia.org/wiki/List_of_video_game_console_palettes
color[] nesPalette = {
  #7C7C7C, #0000FC, #0000BC, #4428BC, #940084, #A80020, #A81000,
#881400, #503000, #007800, #006800, #005800, #004058, #BCBCBC, #0078F8,
#0058F8, #6844FC, #D800CC, #E40058, #F83800, #E45C10, #AC7C00, #00B800,
#00A800, #00A844, #008888, #F8F8F8, #3CBCFC, #6888FC, #9878F8, #F878F8,
#F85898, #F87858, #FCA044, #F8B800, #B8F818, #58D854, #58F898, #00E8D8,
#787878, #FCFCFC, #A4E4FC, #B8B8F8, #D8B8F8, #F8B8F8, #F8A4C0, #F0D0B0,
#FCE0A8, #F8D878, #D8F878, #B8F8B8, #B8F8D8, #00FCFC, #F8D8F8, #000000
};

PImage butterflyImage;

void setup() {
  size(440, 346);
  butterflyImage= loadImage("butterfly.jpg");
  butterflyImage.resize(width, height);

  //loop over pixels and apply filter to each pixel
  for(int y = 0; y < butterflyImage.height; y++){
   for(int x = 0; x < butterflyImage.width; x++){
     color in = butterflyImage.get(x, y);
     color out = getClosestNesColor(in);
     butterflyImage.set(x, y, out);
   }
  }

  noLoop();
}

//given the in color, returns the color in the NES palette closest to that color
color getClosestNesColor(color in){

  float inRed = red(in);
  float inGreen = green(in);
  float inBlue = blue(in);

  color out = in;
  float minColorDistance = 100000;

  //loop over NES palette to find closest color
  for(color nesColor : nesPalette){

    float nesRed = red(nesColor);
    float nesGreen = green(nesColor);
    float nesBlue = blue(nesColor);

    //treat colors as 3D points and get distance between them to find closest color
    float colorDistance = dist(inRed, inGreen, inBlue, nesRed, nesGreen, nesBlue);

    if(colorDistance < minColorDistance){
      out = nesColor;
      minColorDistance = colorDistance;
    }
  }

  return out;

}

void draw() {
  image(butterflyImage, 0, 0);
}