parse terrain from screeps png

terrain.js

    getPx('https://s3.amazonaws.com/static.screeps.com/map2/'+ roomName+ '.png', function(err, pixels) {
      if (err) {
        throw err;
      }
      let kyskip = 50 * 3 * 3 * 4;
      let kxskip = 3 * 4;
      for (let yy = 0; yy < 50; ++yy) {
        for (let xx = 0; xx < 50; ++xx) {
          let px = pixels.data[xx * kxskip + yy * kyskip] * 0x10000 + pixels.data[xx * kxskip + yy * kyskip + 1] * 0x100 + pixels.data[xx * kxskip + yy * kyskip + 2];
          switch (px) {
            case 0: // wall 
                break;
            case 16773702: // source
                break;
            case 5263440: // controller
              break;            
            case 2829099:
            case 3289650:
              // plain
              break;
            case 2303251: //swamp
            case 0x640000: // keeper
              break;
            default:
              throw new Error('px '+ px);
          }   
        }   
      }