code: function(group,bx,by){
  		var obj = this.nullobj;
  		if     (group==='cell')  { obj = this.getc(bx,by);}
  		else if(group==='cross') { obj = this.getx(bx,by);}
  		else if(group==='border'){ obj = this.getb(bx,by);}
  		else if(group==='excell'){ obj = this.getex(bx,by);}
  		else if(group==='obj')   { obj = this.getobj(bx,by);}
  		return obj;
  	}
docs: --------------------------------------------------------------------------- bd.getObjectPos()  (X,Y)の位置にあるオブジェクトを計算して返す ---------------------------------------------------------------------------