Rotated Tiles Background

Hi Everyone,

I have a image of burlap @ 500 width x 430 height. I need to tile this as my entire background for my full screen flash site. I need help to flip the image horizontally for every other placement horizontally, and then i need it to flip vertically for every other Vertical placement. So the image only looks seamless if i do this. I have a illustration below to help show what i mean.

Without Flipping:

What i need with Flipping:


// Background Pattern

import flash.display.*;
import flash.geom.*;
matrix = { matrixType:"box",x:50,y:10,w:Stage.width,h:Stage.height,r:toRadians(45)}
_global.backbitmap = BitmapData.loadBitmap('Burlap.jpg');

this.createEmptyMovieClip("Background_mc",this.getNextHighestDepth());
Background_mc.matrix = new Matrix(); 
Background_mc.smoothing = true;
Background_mc.beginBitmapFill(_global.backbitmap, matrix, true, smoothing);
Background_mc.moveTo(0, -700);
Background_mc.lineTo(1600, -700);
Background_mc.lineTo(1600, 639);
Background_mc.lineTo(0, 639);
Background_mc.lineTo(0, -700);
Background_mc.endFill();
Background_mc._alpha = 100;
Background_mc._y = 90;

Thanks,

Martha Stewart