https://wiki.jmonkeyengine.org/legacy/doku.php/jme3:math#slerp

//the rotation half-way between these two

Quaternion q3 = q1.slerp(q2, 0.5f);//Failed because of Quaternion required instead of void

In 3.0 MUST be like that:

```
/*
You can interpolate rotations between two quaternions using spherical linear
interpolation (slerp).
*/
Quaternion Xroll45 = new Quaternion();
Xroll45.fromAngleAxis(45 * FastMath.DEG_TO_RAD, Vector3f.UNIT_X);
```

//

Quaternion Yroll45 = new Quaternion();

Yroll45.fromAngleAxis(45 * FastMath.DEG_TO_RAD, Vector3f.UNIT_Y);

/*

the rotation half - way between these two

*/

Quaternion halfBetweenXroll45Yroll45 = new Quaternion();

halfBetweenXroll45Yroll45.slerp(Yroll45, Yroll45, 0.5f);

geom2.setLocalRotation(halfBetweenXroll45Yroll45);