WiiFlash Tip #2 – Smoothing out the edges

This is tip #2 in my series on WiiFlash.

Once you have data coming in the from a Wii controller, the first thing you’ll notice is how precise it is. I don’t have it in front of me, but the precision goes about 15 places past the decimal (4.042584267432343…). If you just convert the data from radians to degrees, WiimoteObj.roll*(180 / Math.PI), and apply it to a sprite with an enter frame event, you’ll see it wobble all like mad.

There are two things that you must smooth out to best use the Wii controller – the roll, pitch and yaw of the controller, and the animation of the Wii mouse pointer.

1 – Smoothing Roll, Pitch and Yaw Data

I’m only going to demonstrate for the roll value – it’s the same for pitch and yaw. There are probably numerous ways to optimize this code, but it’s working me right now. My method involves comparing the current value to the last value and checking to see if it’s outside of a tolerance value. If so, then the value is updated, if not, then it’s ignored. I’ve found that 10 degrees works well for me, but you can change it depending on how precise you need it to be. This code assumes that you have an instance of the Wiimote class, WiimoteObj, and have the listeners set up to call the updateWiiMoteData function when the WiimoteEvent.UPDATE event occurs.

private var WiiMPitchDeg:int;
private var WiiMPitchDegPrev:int;
// to convert radians to degrees
private static const TO_DEG:Number = 180 / Math.PI;
// smoothes out roll, pitch and yaw values, smaller = more precision
private static const WIGGLE_TOL:int = 10;

private function updateWiiMoteData(pEvt:WiimoteEvent):void {
WiiMRollDeg = int(WiimoteObj.roll*TO_DEG);
var rDelta:Number = Math.abs(Math.abs(WiiMRollDegPrev) – Math.abs(WiiMRollDeg));
if(rDelta < WIGGLE_TOL) WiiMRollDeg = WiiMRollDegPrev;

As you can see it’s pretty simple and works well.

2 – Smoothing out the Wii mouse cursor

This one is very easy. All that you need to do is to slightly tween your cursor sprite from it’s current location to the location that the Wii more is pointing to. Here’s my function, same assumptions as above. wiiPoint is a Point object containing the location you calculated for where the controller is pointing to. I’m using Tweener for the animation.

 private function updateCursor():void {
var newx:int = 0;
var newy:int = 0;
var newr:int = 0;
try {
newx = wiiPoint.x;
newy = wiiPoint.y;
newr = WiimoteObj.roll;
} catch (e:*) {
// no good data – the ‘mote hasn’t seen the IR points
newx = 0;
newy = 0;
newr = 0;
Tweener.addTween(CursorSprite, {x:newx, y:newy, rotation:newr, time:.1, transition:”easeOutQuad” } );

For your VirtualMouse object, be sure to set it’s x and y properties to the location of the cursor sprite, not where your code says the Wii is pointing at.


  1. hi,

    a other and fast way for smoothing the roll, pitch and yaw values is to interpolate about this. Usaually i work with an array witch has a length of 10. On update i shift the first element and push the new value. Yet i could grab the average.


Leave a Reply