Following up on my past two posts.

The prior two experiments were done using a png with a transparent background. i made it, so i know what i wanted… but what if the spritesheet you’re using isn’t in a format without an alpha channel?
I ran a test using a png with a background color to see if i can strip out a specified color and still get the rendered staes i want.
Yes i can- by using the threshold method of the BitmapData class.

the picture above is a screenshot of my test movie that shows the image loaded in the upper-left corner.

To recap: i load an image into a mc, create a BitmapData instance and BitmapData.draw(mc) to capture the bitmap. Then i (aside from here) delete the mc, pass the BitmapData instance onto a “dissector” and render each state dependant on user action.
In order to remove the offending color (in this case all pixels with a value of 0×00333333), run the following before passing the BitmapData instance on:

// — where  

//              __bmp is my BitmapData instance,  

//              __threshold = 0×00333333,  

//              w and h are the dimesions of the loaded image  

// –  

private function applyThreshold(w:Number, h:height)  


    __bmp.threshold(__bmp, new Rectangle(0, 0, w, h), new Point(0, 0), “==”, __threshold, 0xffff00, 0xffffff, false);  


I kept the dropShadow in there to see if it still applied afterward, and lo and behold! excellent.
One thought… for some reason when i set the color and mask arguments both to white, it didn’t mask- don’t know why, but i didn’t investigate too hard.
Two thought… if my states held that same offending color (say in the eyes), it will remove it – i’ll have to work on that.

Posted in Flash, Flash8.