moving object on x axis without affecting z axis

Questions & Answers
1

I have an NPC object in my 2d sidescrolling game.
While he is far away from the player, I want him to patrol nearby area, by changing it’s x coordinate in a range, but while x coordinate is changing, z coordinate is changing too. Here is the code:

#pragma strict
var range : float;
private var start_x : float;



function Start () {
	start_x = transform.position.x;
	range = gameObject.GetComponent(NPC_set_attributes).npc_patrolling_range;
}

function Update () {

	transform.Translate(Vector3(gameObject.GetComponent(NPC_set_attributes).npc_move_speed*Time.deltaTime, 0.0, 0.0), Space.Self);
	
	if(transform.position.x >= start_x + range){
		Change_direction();
	} else if(transform.position.x <= start_x-range) {
		Change_direction();
	}
}

function Change_direction () {
	gameObject.GetComponent(NPC_set_attributes).npc_move_speed = -gameObject.GetComponent(NPC_set_attributes).npc_move_speed;
	gameObject.GetComponent(NPC_set_attributes).npc_facing_left = !gameObject.GetComponent(NPC_set_attributes).npc_facing_left;
}

Don’t know what to do. “Freeze Position Z” won’t help, because I need to be able to move my object on z axis too.

2

Space.Self in Translate makes the object move in its local directions - if the object has any rotation, it will move in other axes too. Try Space.World instead: this will Translate only in the X axis with this code. By the way, you could improve performance and write a lot less if the script reference was cached in a variable at Start:

#pragma strict

var range : float;
private var start_x : float;
private var attribs: NPC_set_attributes; // reference to the NPC_set_attributes script

function Start () {
	start_x = transform.position.x;
	attribs = GetComponent(NPC_set_attributes); // get the script
	range = attribs.npc_patrolling_range;
}

function Update () {
	transform.Translate(Vector3(attibs.npc_move_speed*Time.deltaTime, 0.0, 0.0), Space.World);
	if(transform.position.x >= start_x + range){
		Change_direction();
	} else if(transform.position.x <= start_x-range) {
		Change_direction();
	}
}

function Change_direction () {
	attribs.npc_move_speed = -attribs.npc_move_speed;
	attribs.npc_facing_left = !attribs.npc_facing_left;
}