public Quaternion set(Quaternion q) {
        this.x = q.x;
        this.y = q.y;
        this.z = q.z;
        this.w = q.w;
        return this;
    }
Copies all 4 components from the argument.

@param q the quaternion to copy (not null, unaffected)
@return the (modified) current instance (for chaining)
jme3-core/src/main/java/com/jme3/math/Quaternion.java