BitmapData getPixel on rotating movieClip?

This may be more of a math question as I try variations on this problem. I'm trying to get the rgb value from a pixel area on the stage that a bitmap is rotating in. I made it work for the y by adjusting the getPixel location in the bitmap, but I think I need to use some sin/cos to "rotate" the x/y location for the getRGB...

am I making this harder than it needs to be?

any ideas?? fla attached...

Thanks!

so the respect of the point you are checking is in respect to outside of the circle_mc which is rotated and you are comparing against just the BitmapData.

All you've go to do is transform the position to inside of the circle. Yeah it'd take some sin and cos, or you can use matrices, OR you could use the Flash defined method for doing it.

like so:

circle_mc.globalToLocal( new Point( stagePositionX, stagePositionY ) );

then check those values... remember bitmaps are whole pixels, integers only work. So either floor or round for the effect you want.

sin and cos would be your answer as well. But it's a lot more work then you need. And depends upon the point in which the circle_mc rotates, I'm assuming the center so you'd basically just take the distance from the point checking to the center of the circle. then multiply those by sin and cosine of the angle of rotation:

Code:

---

var d:Number = //distance between global point to check and global point of the circle's center
var ix:Number = Math.cos(circle_mc.rotation * Math.PI / 180); //convert to radians
ix *= d;
var iy:Number = Math.sin(circle_mc.rotation * Math.PI / 180);
iy *= d;

---

the matrix method is just a lot of processing work in comparison, so don't even both with it. But you basically just transform the matrix of one point by the other and pop out the resulting point. Due to Flash's ****ty Matrix Class that offers no real matrix math accept for "concat" it is highly inefficient and clumsy.

Got it...In case anyone else needs to do something like this, I used the following equations to set the adjustX and adjustY.

angle = the _x of the rot slider
rad = the _x of the y slider

adjustX=cx+Math.sin(angle)*rad;
adjustY=cy+Math.sin(angle)*rad;

Works GREAT!!

Thanks!