[ODE] properly QuaternionToEuler

[Eugen Lofing]

Hello alltogether!

I actually use for QuaternionToEuler-converting following algorithm

---------------------------------------------------------------------
	dReal w, x, y, z;
	w = quaternion[0];
	x = quaternion[1];
	y = quaternion[2];
	z = quaternion[3];
	double sqw = w * w;    
	double sqx = x * x;    
	double sqy = y * y;    
	double sqz = z * z; 
	// heading
	float Z = (float) (atan2(2.0 * (x*y + z*w),(sqx - sqy - sqz + sqw)) *
GRAD_PI); 
	// bank
	float X = (float) (atan2(2.0 * (y*z + x*w),(-sqx - sqy + sqz + sqw)) *
GRAD_PI);  
	// attitude
	float Y = (float) (asin(-2.0 * (x*z - y*w)) * GRAD_PI);
---------------------------------------------------------------------

but it is buggy, because I have following ranges for Y (attitude):
0..90..0..-90..0
^              |
|______________|

instead of 0..360, or -180..180 like by X and Z :(

I assume there are 3 cases to differ by checking value of (x*z - y*w)

But I don't know how, nor have some formula..

Do somebody know?  

Thank u for all hints and suggestions :)

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