Hello.
For the last month, I’ve been trying to create good RTS “Grab 'n drag” styled camera. After realising how painfully hard it is, I decided to post my script here, so people can use it and not worry about writing their own.
Here’s the script and a little instruction below:
(The zooming isn’t included yet)
using UnityEngine;
using System.Collections;
public class GalCamv2 : MonoBehaviour {
//Variables----------------------------------
public Transform Cam;
public Transform RotationPoint;
public Transform Parent;
public float ySpeed = 400f;
public float xSpeed = 400f;
private float x;
private float y;
private float x2;
private float y2;
//------------------------------------------
void Start () {
Vector3 CamPos = new Vector3 (0, MinDis, 0);
Cam.position = CamPos;
}
void Update () {
//Parents and stuff------------------------
if(!Input.GetMouseButtonUp(0) !Input.GetMouseButton(1)){
Vector3 campos = Parent.position;
Cam.position = campos;
}
if(Input.GetMouseButtonUp(0)){
Vector3 ParPos = Cam.position;
Parent.position = ParPos;
}
if(Input.GetMouseButtonDown(0) | Input.GetMouseButtonUp(1)){
x = 0;
y = 0;
}
//--------------------------------------
//Movement------------------------
if(Input.GetMouseButton(0) PauseChange == 0f){
Cam.parent = Parent;
x+=Input.GetAxis("Mouse X") * xSpeed * 0.02f ;
y-=Input.GetAxis("Mouse Y") * ySpeed * 0.02f ;
Vector3 CamLocPos = new Vector3 (-x , 0, y);
Cam.localPosition = CamLocPos;
}
//--------------------------------------
//RotationPoint-----------------
if(!Input.GetMouseButton(0) !Input.GetMouseButton(1) ){
Cam.parent = null;
RaycastHit hit;
Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
if (Physics.Raycast(ray, out hit, 1000)){
RotationPoint.position = hit.point;
}
}
//--------------------------------------
//Rotation-------------------------------
if(Input.GetMouseButton(1) PauseChange == 0f){
Vector3 parpos2 = Cam.position;
Parent.position = parpos2;
Cam.parent = RotationPoint;
x2+=Input.GetAxis("Mouse X") * xSpeed * 0.02f ;
y2-=Input.GetAxis("Mouse Y") * ySpeed * 0.02f ;
Quaternion rotation = Quaternion.Euler(y2, x2, 0);
RotationPoint.rotation = rotation;
}
//--------------------------------------
//Something Important-------------------
if(Input.GetMouseButtonUp(1)){
Quaternion ParRot = Quaternion.Euler(0, x2, 0);
Parent.rotation = ParRot;
}
//--------------------------------------
}
}
Instructions:
-Cam is obviously the camera, parent and rotation point are empty game objects.
-You need to have a plane for this to work, because the RotationPoint moves on a collider.
So yeah, I hope that I helped somebody 
-Xentarok
P.S.:
If you have any questions or problems write about them below.
P.S.2:
My english is bad, so sorry for the mistakes.