ActionScript 3.0 :: Correction Applied To The Rotation Y Angle When Using PerspectiveProjection?

I have a stage with and height of :600x400 On this stage i have 3 squares that have a centerpoint in the middle. The square are 90 (width) and 80 (height)The first square is aligned to the left site and the second one in the middle and the third one on the right  The perspectiveProjection is setup using the middle of the stage as it projectionCenter.When i rotate all squares to 90 degrees (rotationY) than only the middle one is now not visible anymore, at that point i want to switch the image inside the square. But at 90 degrees the left and right squares are not invisible..  For the left square that point wouldbe at 90 - 22, and the right one 90 + 22.   Is there a way to calculate the correction value (22) in this example?
 
What i don't want is to give every square it's own perspectiveProjecten , then it would work but you have a completely different3D rotation.The only thing that goes wrong in my example is that the image from the left and right square are not changed at the right time, because 90 degrees on the left square does not mean it it not visible at that point.
 
And here is the code:
 
import flash.display.MovieClip;import flash.geom.Point;import flash.geom.PerspectiveProjection;import fl.transitions.*;import fl.transitions.easing.*
var squares:Array = [c1, c2, c3];

[code]....