See my previous answer's comment thread for context on this answer.
There are two approaches to get your camera to orbit around a point. Before you do anything else, create an empty GameObject in Unity and set it at the fixed point around which you wish your camera to orbit. Make sure the GameObject is in the Camera's line of sight. Then parent your camera to the Empty GameObject.
For the easy (but more rigid) approach, attach your TouchCamera script to the Empty GameObject. Remove the TouchCamera script from your camera. Now add this line public Camera camera above the start of the Update method in the script. In your script replace all occurrences of GetComponent<Camera>() with camera. Save your script and go back into Unity. Finally, click on your Empty GameObject and drag your Camera into the Serialized Camera field in your TouchCamera component. This approach essentially moves control of the camera to the Empty GameObject.
For a more convoluted (but more flexible) approach, create a new C# script and name it "CameraControl". Then copy and paste the following code into the script (replacing any code already there).
using UnityEngine;
using UnityEngine.UI;
using System;
using System.Collections;
public class CameraControl : MonoBehaviour {
Vector2?[] oldTouchPositions = {
null,
null
};
Vector2 oldTouchVector;
float oldTouchDistance;
public Transform CenterOfRotation;
public Camera camera;
private Vector2 actualCenter;
private Vector2 prevTouchDelta;
private Vector3 prevMousePosition;
private bool rotate;
void Start()
{
//swap with below commented line for y rotation.
actualCenter = new Vector2(CenterOfRotation.position.x, CenterOfRotation.position.z);
//actualCenter = new Vector2(CenterOfRotation.position.x, CenterOfRotation.position.y);
}
void Update() {
if(!rotate){
if (Input.touchCount == 0) {
oldTouchPositions[0] = null;
oldTouchPositions[1] = null;
}
else if (Input.touchCount == 1) {
if (oldTouchPositions[0] == null || oldTouchPositions[1] != null) {
oldTouchPositions[0] = Input.GetTouch(0).position;
oldTouchPositions[1] = null;
}
else {
Vector2 newTouchPosition = Input.GetTouch(0).position;
transform.position += transform.TransformDirection((Vector3)((oldTouchPositions[0] - newTouchPosition) * camera.orthographicSize / camera.pixelHeight * 2f));
oldTouchPositions[0] = newTouchPosition;
}
}
else {
if (oldTouchPositions[1] == null) {
oldTouchPositions[0] = Input.GetTouch(0).position;
oldTouchPositions[1] = Input.GetTouch(1).position;
oldTouchVector = (Vector2)(oldTouchPositions[0] - oldTouchPositions[1]);
oldTouchDistance = oldTouchVector.magnitude;
}
else {
Vector2 screen = new Vector2(camera.pixelWidth, camera.pixelHeight);
Vector2[] newTouchPositions = {
Input.GetTouch(0).position,
Input.GetTouch(1).position
};
Vector2 newTouchVector = newTouchPositions[0] - newTouchPositions[1];
float newTouchDistance = newTouchVector.magnitude;
transform.position += transform.TransformDirection((Vector3)((oldTouchPositions[0] + oldTouchPositions[1] - screen) * camera.orthographicSize / screen.y));
//transform.localRotation *= Quaternion.Euler(new Vector3(0, Mathf.Asin(Mathf.Clamp((oldTouchVector.y * newTouchVector.x - oldTouchVector.x * newTouchVector.y) / oldTouchDistance / newTouchDistance, -1f, 1f)) / 0.0174532924f, 0));
camera.orthographicSize *= oldTouchDistance / newTouchDistance;
transform.position -= transform.TransformDirection((newTouchPositions[0] + newTouchPositions[1] - screen) * camera.orthographicSize / screen.y);
oldTouchPositions[0] = newTouchPositions[0];
oldTouchPositions[1] = newTouchPositions[1];
oldTouchVector = newTouchVector;
oldTouchDistance = newTouchDistance;
}
}
}
else{
InwardRotation();
}
}
void OnGUI()
{
rotate = GUILayout.Toggle(rotate, "Toggle For Rotation", "Button");
}
void InwardRotation()
{
//mouse version
if(Input.GetMouseButton(0))
{
//distance from center of screen to touch
Vector3 centerScreen = camera.ViewportToScreenPoint(new Vector3(0.5f, 0.5f, 1));
Vector3 mouseDelta = Input.mousePosition - new Vector3(centerScreen.x, centerScreen.y, 0f);
//if mouse doesn't move very much, don't rotate
if(mouseDelta.sqrMagnitude < 0.1f)
return;
//attempts to make movement smoother
if(prevMousePosition == Vector3.zero)
prevMousePosition = mouseDelta;
//this gets the angle between the current touch and the last touch
float theta = Mathf.Atan2(mouseDelta.y, mouseDelta.x) - Mathf.Atan2(prevMousePosition.y, prevMousePosition.x);
//Gets the rotated coordinates of the camera. Swap with below commented line for y rotation.
Vector2 newPos = RotatedCoordinates(transform.position.x, transform.position.z, theta, CenterOfRotation.position, true);
//Vector2 newPos = RotatedCoordinates(transform.position.x, transform.position.y, theta, CenterOfRotation.position, true);
Debug.Log("New Pos = " + newPos);
//swap with below commented line for y rotation.
transform.localPosition = new Vector3(newPos.x, transform.localPosition.y, newPos.y);
//transform.localPosition = new Vector3(newPos.x, newPos.y, transform.localPosition.z);
transform.LookAt(CenterOfRotation);
prevMousePosition = mouseDelta;
}
if(Input.touches.Length > 0f)
{
//distance from center of screen to touch
Vector3 centerScreen = camera.ViewportToScreenPoint(new Vector3(0.5f, 0.5f, 1));
Vector2 touchDelta = Input.GetTouch(0).position - new Vector2(centerScreen.x, centerScreen.y);
//if mouse doesn't move very much, don't rotate
if(touchDelta.sqrMagnitude < 0.1f)
return;
//attempts to make movement smoother
if(prevTouchDelta == Vector2.zero)
prevTouchDelta = touchDelta;
//this gets the angle between the current touch and the last touch
float theta = Mathf.Atan2(touchDelta.y, touchDelta.x) - Mathf.Atan2(prevTouchDelta.y, prevTouchDelta.x);
//Gets the rotated coordinates of the camera. Swap with below commented line for y rotation.
Vector2 newPos = RotatedCoordinates(transform.position.x, transform.position.z, theta, CenterOfRotation.position, true);
//Vector2 newPos = RotatedCoordinates(transform.position.x, transform.position.y, theta, CenterOfRotation.position, true);
Debug.Log("New Pos = " + newPos);
//swap with below commented line for y rotation.
transform.localPosition = new Vector3(newPos.x, transform.localPosition.y, newPos.y);
//transform.localPosition = new Vector3(newPos.x, newPos.y, transform.localPosition.z);
transform.LookAt(CenterOfRotation);
prevTouchDelta = touchDelta;
}
else{
prevTouchDelta = Vector2.zero;
}
}
/// <summary>
/// This method returns the coordinates of a plane rotated about its origin. It translates a point from one place on a unit circle to another.
/// </summary>
/// <returns>The coordinates.</returns>
/// <param name="x">The x coordinate.</param>
/// <param name="y">The y coordinate.</param>
/// <param name="theta">Theta.</param>
/// <param name="ThetaInRad">If set to <c>true</c> theta in RAD.</param>
public Vector2 RotatedCoordinates(float x, float y, float theta, Vector2 center, bool ThetaInRad = false)
{
if(!ThetaInRad)
theta *= Mathf.Deg2Rad;
Vector2 XY = new Vector2((Mathf.Cos(theta) * (x - center.x) - Mathf.Sin(theta) * (y - center.y)) + center.x, (Mathf.Sin(theta) * (x - center.x) + Mathf.Cos(theta) * (y - center.y)) + center.y);
return XY;
}
}
Now attach this to your Camera (which should be a child of the empty GameObject) and remove the TouchCamera script. You'll notice two fields inside the CameraControl component, one that reads "Center Of Rotation" and one that reads "Camera". Drag the Empty GameObject and your Camera onto these fields respectively. This script will throw Null Reference Errors if you skip this step. Now just hit play. When you click the Toggle For Rotation button in the top left corner of the play window, you will be able to rotate the camera by dragging either the mouse pointer or a single finger around the center of the screen. You can unparent the Camera from the Empty GameObject and the script will still work. You can also orbit around any point in space by providing a different Transform. With a bit of editing, you could also eliminate the Transform entirely and use a Vector3 as the reference point in World Space, but you would need to control the Camera's actual rotation yourself without the line transform.LookAt(CenterOfRotation);. You can change the axis of rotation by editing three lines, located at roughly line 30, line 145, and line 151.
