Unity实现物体左右移动效果

using unityengine;
using system.collections;
 
//add this script to the platform you want to move.
//左右移动的平台
public class movingplatform : monobehaviour {
 
 //platform movement speed.平台移动速度
 public float speed;
 
 //this is the position where the platform will move.平台移动的位置
 public transform moveposition;//创建一个空物体作为移动的位置
 
 private vector3 startposition;
 private vector3 endposition;
 private bool onthemove;
 
 // use this for initialization
 void start () {
 //store the start and the end position. platform will move between these two points.储存左右两端点位置
 startposition = this.transform.position;
 endposition = moveposition.position;
 }
 
 void fixedupdate () {
 
 float step = speed * time.deltatime;
 
 if (onthemove == false) {
 this.transform.position = vector3.movetowards (this.transform.position, endposition, step);
 }else{
 this.transform.position = vector3.movetowards (this.transform.position, startposition, step);
 }
 
 //when the platform reaches end. start to go into other direction.
 if (this.transform.position.x == endposition.x && this.transform.position.y == endposition.y && onthemove == false) {
 onthemove = true;
 }else if (this.transform.position.x == startposition.x && this.transform.position.y == startposition.y && onthemove == true) {
 onthemove = false;
 }
 } 
 
}