DCGO/Assets/Effect/48 Particle Effect Pack/Script/csMouseOrbit.cs

using UnityEngine;
using System.Collections;

public class csMouseOrbit : MonoBehaviour
{

    public Transform Target;
    public float distance;

    public float xSpeed = 250.0f;
    public float ySpeed = 120.0f;

    public float yMinLimit = -20.0f;
    public float yMaxLimit = 80.0f;

    private float x = 0.0f;
    private float y = 0.0f;
    public float CameraDist = 10;

    // Use this for initialization
    void Start()
    {
        Vector3 angles = transform.eulerAngles;
        x = angles.x;
        y = angles.y;
        distance = 30;

        if (this.GetComponent<Rigidbody>() == true)
            GetComponent<Rigidbody>().freezeRotation = true;
    }

    // Update is called once per frame
    void LateUpdate()
    {
        if (Target)
        {
            x += Input.GetAxis("Mouse X") * xSpeed * 0.02f;
            y += Input.GetAxis("Mouse Y") * ySpeed * 0.05f;

            y = ClampAngle(y, yMinLimit, yMaxLimit);

            Quaternion rotation = Quaternion.Euler(y, x, 0);
            Vector3 position = rotation * new Vector3(0, 0, -distance) + Target.position;

            transform.rotation = rotation;
            transform.position = position;
            distance = CameraDist;
        }
    }

    float ClampAngle(float ag, float min, float max)
    {
        if (ag < -360)
            ag += 360;
        if (ag > 360)
            ag -= 360;
        return Mathf.Clamp(ag, min, max);
    }
}