How to make a player move in a straight line?

Please tell me how I can cancel the player from moving to the left and right and the rotation (I want to do moving in a straight line).
Sorry for my bad English.

 

Are you familiar with the Cartesian Plane?

 

[QUOTE = "Muqsit, post: 55303, участник: 25"] Вы знакомы с картезианским самолетом ? [/ QUOTE]
yes, but not in three-dimensional space

 

That should be easy for you then.

When you say a "straight line", do you mean a straight line from any point of reference or do you mean a straight line limited to exactly North, exactly South, exactly East and exactly West?

 

[QUOTE = "Muqsit, post: 55341, участник: 25"] Тогда вам будет легко.

Когда вы говорите «прямую линию», вы имеете в виду прямую линию из любой точки отсчета или вы имеете в виду прямую линию, ограниченную точно Северным, точно южным, точно восточным и точно западным? [/ QUOTE]
I want the player from the point to go only to the north and south

 

Maybe this will help: Minecraft Coordinates. Basically, just cancel PlayerMoveEvent if the X or Y value changes between the to and from point, I believe.