toEuler method

Map<String, dynamic> toEuler(Map<String, dynamic> euler)

Returns an euler angel (YXZ order) representation of this quaternion.

Implementation

Map<String,dynamic> toEuler(Map<String,dynamic> euler ) {
	// from 3D Math Primer for Graphics and Game Development
	// 8.7.6 Converting a Quaternion to Euler Angles

	// extract pitch
	final sp = - 2 * ( y * z - x * w );

	// check for gimbal lock
	if ( sp.abs() > 0.9999 ) {
		// looking straight up or down
		euler['x'] = math.pi * 0.5 * sp;
		euler['y'] = math.atan2( x * z + w * y, 0.5 - x * x - y * y );
		euler['z'] = 0;
	}
    else { //todo test
		euler['x'] = math.asin( sp );
		euler['y'] = math.atan2( x * z + w * y, 0.5 - x * x - y * y );
		euler['z'] = math.atan2( x * y + w * z, 0.5 - x * x - z * z );
	}

	return euler;
}