public Quaternion fromAnglesXY (float x, float y) {
        float hx = x * 0.5f, hy = y * 0.5f;
        float sx = FloatMath.sin(hx), cx = FloatMath.cos(hx);
        float sy = FloatMath.sin(hy), cy = FloatMath.cos(hy);
        return set(cy*sx, sy*cx, -sy*sx, cy*cx);
    }
public Quaternion fromAnglesXY ( float x , float y ) { float hx = x * 0.5f , hy = y * 0.5f ; float sx = FloatMath . sin ( hx ) , cx = FloatMath . cos ( hx ) ; float sy = FloatMath . sin ( hy ) , cy = FloatMath . cos ( hy ) ; return set ( cy * sx , sy * cx , - sy * sx , cy * cx ) ; }
Sets this quaternion to one that first rotates about x by the specified number of radians,
then rotates about y by the specified number of radians.