getClosestPart.go

func getClosestPart(mp *map[PixelColor]image.Image, pix color.Color) image.Image {
   c := color.RGBAModel.Convert(pix).(color.RGBA)
   key := [3]uint8{c.R, c.G, c.B}

   if part, ok := (*mp)[key]; ok {
      return part
   }

   var minD *float64
   var prt *image.Image

   for m, i := range *mp {

      o := int64(m[0])
      a := int64(c.R)
      rr := float64(o - a)

      rd := math.Pow(rr, 2)
      gd := math.Pow(float64(int64(m[1])-int64(c.G)), 2)
      bd := math.Pow(float64(int64(m[2])-int64(c.B)), 2)

      d := math.Sqrt(rd + gd + bd)
      if minD == nil || *minD > d {
         minD = &d
         prt = &i
      }
   }

   (*mp)[key] = *prt

   return *prt
}