3D RTS camera

I had to create something similar for an isometric game, here is what I did:

I created an empty gameobject as a "Camera Helper", then made the Camera a child of it, and set the camera's transform to my liking (position from parent, rotation etc.). Just make sure that the camera's viewport center is pointing directly at the helper object.

The camera helper is set at whatever position you wish, and if want your camera to move, you instead just move and roate the helper object (along the x and z axes, if you wish). This means you get to use things like transform.forward which is very helpful.

Note that for rotations around the y axis (sideways), you should rotate the helper, and for the x axis (up&down), the camera itself.

Here's some camera move an zoom code. The script is attached to the camera.

You can ignore everything about the orthographic mode if you camera is perspective, and vice versa. I just liked to have the option of changing it during runtime for specific camera shots.

 var CameraMover : GameObject;
     
     var orthZoomStep : float= 10.0f;
     var orthZoomMaxSize : int = 500;
     var orthZoomMinSize : int = 300;
      
     var orthographicView : boolean;//set to true if the Camera is set to orthographic.
     
     function Start()
     {
          if(GetComponent(Camera).orthographic == true)
          {
               orthographicView = true;
          }
     }
     
     function Update () 
     {
     
         if(Input.GetKey(KeyCode.UpArrow))
         {
             CameraMover.transform.Translate(Vector3.forward * ScrollSpeed);
         }
         
         if(Input.GetKey(KeyCode.DownArrow))
         {
             CameraMover.transform.Translate(-Vector3.forward * ScrollSpeed);
         }
         
         if(Input.GetKey(KeyCode.LeftArrow))
         {
             CameraMover.transform.Translate(-Vector3.right * ScrollSpeed);
         }
         
         if(Input.GetKey(KeyCode.RightArrow))
         {
             CameraMover.transform.Translate(Vector3.right * ScrollSpeed);
         }
         
         if(Input.GetKey(KeyCode.UpArrow) && Input.GetKey(KeyCode.LeftArrow))
         {
             CameraMover.transform.Translate((Vector3.forward + (-Vector3.right)) * ScrollSpeed);
         }
         
         if(Input.GetKey(KeyCode.UpArrow) && Input.GetKey(KeyCode.RightArrow))
         {
             CameraMover.transform.Translate((Vector3.forward + Vector3.right) * ScrollSpeed);
         }
         
         if(Input.GetKey(KeyCode.DownArrow) && Input.GetKey(KeyCode.LeftArrow))
         {
             CameraMover.transform.Translate((-Vector3.forward + (-Vector3.right)) * ScrollSpeed);
         }
         
         if(Input.GetKey(KeyCode.DownArrow) && Input.GetKey(KeyCode.RightArrow))
         {
             CameraMover.transform.Translate((-Vector3.forward + Vector3.right) * ScrollSpeed);
         }
     
    
         zoomCamera();
     }
     
     function zoomCamera()
     {
       
         // zoom out
         if (Input.GetAxis("Mouse ScrollWheel") < 0)//Mouse Wheel Down
         {
             if(orthographicView)
             {
                 if (camera.orthographicSize <=orthZoomMaxSize)
                 {
                     camera.orthographicSize += orthZoomStep;
                 }
                     
             }
             else
             {
                 if (camera.fieldOfView<=150)
                 {
                     camera.fieldOfView +=5;
                 }
                        
             }
         }
         // zoom in
         if (Input.GetAxis("Mouse ScrollWheel") > 0)//Mouse Wheel Up
            {
             if(orthographicView)
             {
                 if (camera.orthographicSize >= orthZoomMinSize)
                 {
                     camera.orthographicSize -= orthZoomStep; 
                 }
                                
             }
             else
             {
                 if (camera.fieldOfView>2)
                 {
                     camera.fieldOfView -=5;
                 }  
             }
      }