EncodeDecode16bit

float encode16bits(float2 xy16)
{
   xy16 = floor( xy16/16 );
   float packed = xy16.x*16 + xy16.y;
   packed /= 255.0f;
   return packed;
}

float2 decode8bits(float packed)
{
   packed *= 255.0f;
   float2 xy;
   xy.x = floor(packed / 16 );
   xy.y = fmod(packed,16);
   xy *= 16;
   xy /= 255.0f;
   return xy;
}