在正方体\(ABCD-A_{1}B_{1}C_{1}D_{1}\)中\((\)如图\()\),已知点\(P\)在直线\(BC_{1}\)上运动,则下列四个命题:
\(①\)三棱锥\(A-D_{1}BC\)的体积不变;
\(②\)直线\(AP\)与平面\(ACD_{1}\)所成的角的大小不变;
\(③\)二面角\(P-AD_{1}-C\)的大小不变;
\(④M\)是平面\(A_{1}B_{1}C_{1}D_{1}\)内到点\(D\)和\(C_{1}\)距离相等的点,则\(M\)点的轨迹是直线\(A_{1}D_{1}\).
其中正确命题的编号是\((\) \()\)