在直线坐标系\(xoy\)中,曲线\(C\)\({\,\!}_{1}\)的参数方程为\((α \)为参数\()\)。以坐标原点为极点,\(x\)轴正半轴为极轴,建立极坐标系,曲线\(C\)\({\,\!}_{2}\)的极坐标方程为\(ρ\sin (θ+ \dfrac{π}{4} )=2 \sqrt{2} \).
\((I)\)写出\(C_{1}\)的普通方程和\(C_{2}\)的直角坐标方程;
\((II)\)设点\(P\)在\(C_{1}\)上,点\(Q\)在\(C_{2}\)上,求\(∣PQ∣\)的最小值及此时\(P\)的直角坐标.