void scroll(Directions dir)
    {
    //  if(tilesize==25)
    //      return;
          
    switch(dir)
        {
        case N: this.offy = offy-1; break;
        case S: this.offy = offy+1; break;
        case E: this.offx = offx+1; break;
        case W: this.offx = offx-1; break;
        }
    if(this.offy<0) offy=0;
    if(this.offx<0) offx = 0;
     
    if(offx>(tilenumx-600/tilesize)) offx-=1;
    if(offy>(tilenumy-600/tilesize)) offy-=1;
    
    }