HeptaFish MapEditor中画网格的算法

private var _mapWidth:int;private var _mapHeight:int;private var _tilePixelWidth:int;private var _tilePixelHeight:int;private var _wHalfTile:int;private var _hHalfTile:int;public function DrawGridThree(mapWidth:int, mapHeight:int, tilePixelWidth:int, tilePixelHeight:int):void {    this._mapWidth=mapWidth;    this._mapHeight=mapHeight;    this._tilePixelWidth=tilePixelWidth;    this._tilePixelHeight=tilePixelHeight;    var row:int=this._mapHeight/this._tilePixelHeight;    var col:int = this._mapWidth / this._tilePixelWidth;    this._wHalfTile=int(this._tilePixelWidth/2);    this._hHalfTile=int(this._tilePixelHeight/2);    var grid:Shape = new Shape();    this.addChild(grid);    grid.graphics.beginFill(0xcc6600,.5);    grid.graphics.drawRect(0,0,mapWidth,mapHeight);    grid.graphics.endFill();    grid.graphics.lineStyle(1, 0x000000, 1);                                                    var dblMapWidth:int=col*2+1;    var dblMapHeight:int = row * 2 + 1;    for (var i:int=1; i<dblMapWidth; i=i+2) {                           grid.graphics.moveTo( i*this._wHalfTile, 0 );           if (dblMapHeight+i>=dblMapWidth) {                  grid.graphics.lineTo( dblMapWidth * this._wHalfTile, (dblMapWidth - i) * this._hHalfTile );           } else {                      grid.graphics.lineTo( (dblMapHeight+i)*this._wHalfTile, dblMapHeight*this._hHalfTile );                     }                                          grid.graphics.moveTo( i*this._wHalfTile, 0 );           if (i<=dblMapHeight) {                 grid.graphics.lineTo( 0, i*this._hHalfTile );           } else {                      trace((i-row-1),row);                       grid.graphics.lineTo( (i-row*2-1)*this._wHalfTile, dblMapHeight*this._hHalfTile );                      }      }      for (var j:int=1; j<dblMapHeight; j=j+2) {            grid.graphics.moveTo( 0, j*this._hHalfTile );            if (dblMapHeight-j>=dblMapWidth) {                    grid.graphics.lineTo( dblMapWidth*this._wHalfTile, (dblMapWidth+j)*this._hHalfTile );            } else {                    grid.graphics.lineTo( (dblMapHeight-j)*this._wHalfTile, dblMapHeight*this._hHalfTile );            }       }                               for (var m:int=0; m<dblMapHeight; m=m+2) {              grid.graphics.moveTo( dblMapWidth*this._wHalfTile, m*this._hHalfTile );              if (dblMapWidth-dblMapHeight+m<0) {                  grid.graphics.lineTo( 0, (dblMapWidth+m)*this._hHalfTile );              } else {                  grid.graphics.lineTo( (dblMapWidth-dblMapHeight+m)*this._wHalfTile, dblMapHeight*this._hHalfTile );                        }         }}