public void pollChunkAndDraw() {
    Chunk c;
    synchronized(chunksToDraw) {
      c = getBestChunk(chunksToDraw.iterator(), pos);
      if(c != null) {
        chunksToDraw.remove(c);
      }
    }
    if(c != null) {
      drawChunk(c);
    }
    Chunk b;
    synchronized(biomesToDraw) {
      b = getBestChunk(biomesToDraw.iterator(), pos);
      if(b != null) {
        biomesToDraw.remove(c);
      }
    }
    if(b != null) {
      drawBiome(b);
    }
    if(c != null || b != null) {
      somethingChanged();
    }
  }