Magic Cube

    // Where did we get this sqrt(3)/2 ? From the (default, i.e. 60 degrees - see InternalOutputSurface!)

    // FOV of the projection matrix of the Node onto the Screen.

    // Take a look how the CAMERA_POINT is used in onTouchEvent - (x,y) there are expressed in sort of

    // 'half-NDC' coordinates i.e. they range from +0.5 to -0.5; thus CAMERA_POINT also needs to be

    // in 'half-NDC'. Since in this coordinate system the height of the screen is equal to 1, then the

    // Z-distance from the center of the object to the camera is equal to (scrHeight/2)/tan(FOV/2) =

    // 0.5/tan(30) = sqrt(3)/2.

    // Why is the Z-distance between the camera and the object equal to (scrHeight/2)/tan(FOV/2)?

    // Because of the way the View part of the ModelView matrix is constructed in EffectQueueMatrix.send().

    private final Static4D CAMERA_POINT = new Static4D(0, 0, (float)Math.sqrt(3)*0.5f, 0);