A Problem with freeze rotation and position.

Hello. I am writing a script that freezes the position of objects and allows them to travel on a single axis when given the inputs of the assigned keys X, Y, and Z. This script starts with the variables x, y, and z all deactivated. This leads to my first problem. On start, my object is not constrained in two of the axis. Also, I intended to keep all axis of rotation constrained but none of them are constrained.

Could it be that I am using a modified version of the dragrigidbody script to move the object? I changed lines 20 and 63 on the dragrigidbody script from:

 mainCamera.ScreenPointToRay (Input.mousePosition) 

to:

 mainCamera.ViewportPointToRay(new Vector3(0.5, 0.5, 0))

Here is my drag object script:

 #pragma strict
 var x : boolean = false;
 var y : boolean = false;
 var z : boolean = false;
 function Start () {
     x = false;
     y = false; 
     z = false;
     
 }
 
 function Update () {
     
     rigidbody.constraints = RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY | RigidbodyConstraints.FreezeRotationZ;
     //If it is false
     if(x == false){
         rigidbody.constraints = RigidbodyConstraints.FreezePositionX;
     }
     
     if(y == false){
         rigidbody.constraints = RigidbodyConstraints.FreezePositionY;
     }
     
     if(z == false){
         rigidbody.constraints = RigidbodyConstraints.FreezePositionZ;
     }
     
     //If it is true
     if(x == true){
         rigidbody.constraints = RigidbodyConstraints.FreezePositionY | RigidbodyConstraints.FreezePositionZ;
     }
     
     if(y == true){
         rigidbody.constraints = RigidbodyConstraints.FreezePositionX | RigidbodyConstraints.FreezePositionZ;
     }
     
     if(z == true){
         rigidbody.constraints = RigidbodyConstraints.FreezePositionY | RigidbodyConstraints.FreezePositionX;
     }
     
     if(Input.GetKeyDown(KeyCode.X)){
         x = true;
         y = false;
         z = false;
     }
     if(Input.GetKeyDown(KeyCode.Y)){
         x = false;
         y = true;
         z = false;
     }
     if(Input.GetKeyDown(KeyCode.Z)){
         y = false;
         x = false;
         z = true;
     }
 }

Are there any bugs that I can fix? For the rotation constraints I already tried "rigidbody.constraints = RigidbodyConstraints.FreezeRotation;" with no luck.

Here is my updated script with the rotation problem fixed:

 #pragma strict
 var x : boolean = false;
 var y : boolean = false;
 var z : boolean = false;
 function Start () {
 
     rigidbody.constraints = RigidbodyConstraints.FreezePosition;
 }
 
 function Update () {
     
     rigidbody.constraints = RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY | RigidbodyConstraints.FreezeRotationZ;
         if(Input.GetKeyDown(KeyCode.X)){
         x = true;
         y = false;
         z = false;
     }
     if(Input.GetKeyDown(KeyCode.Y)){
         x = false;
         y = true;
         z = false;
     }
     if(Input.GetKeyDown(KeyCode.Z)){
         y = false;
         x = false;
         z = true;
     }
     //If it is false
     if(x == false){
         rigidbody.constraints = RigidbodyConstraints.FreezePositionX | RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY | RigidbodyConstraints.FreezeRotationZ;
     }
     
     if(y == false){
         rigidbody.constraints = RigidbodyConstraints.FreezePositionY | RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY | RigidbodyConstraints.FreezeRotationZ;
     }
     
     if(z == false){
         rigidbody.constraints = RigidbodyConstraints.FreezePositionZ | RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY | RigidbodyConstraints.FreezeRotationZ;
     }
     
     //If it is true
     if(x == true){
         rigidbody.constraints = RigidbodyConstraints.FreezePositionY | RigidbodyConstraints.FreezePositionZ | RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY | RigidbodyConstraints.FreezeRotationZ;
     }
     
     if(y == true){
         rigidbody.constraints = RigidbodyConstraints.FreezePositionX | RigidbodyConstraints.FreezePositionZ | RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY | RigidbodyConstraints.FreezeRotationZ;
     }
     
     if(z == true){
         rigidbody.constraints = RigidbodyConstraints.FreezePositionY | RigidbodyConstraints.FreezePositionX | RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY | RigidbodyConstraints.FreezeRotationZ;
     }
 
 }