Camera orbit with mouse orbit - limits

 using UnityEngine;
  using UnityEngine;
  using System.Collections;
  
  //[AddComponentMenu("Camera-Control/Mouse drag Orbit with zoom")]
  public class rotateonmouse : MonoBehaviour
  {
      public Transform target;
      public float distance = 5.0f;
      public float xSpeed = 120.0f;
      public float ySpeed = 120.0f;
  
      public float yMinLimit = -20f;
      public float yMaxLimit = 80f;
  
      public float distanceMin = .5f;
      public float distanceMax = 15f;
  
      public float smoothTime = 2f;
  
      float rotationYAxis = 0.0f;
      float rotationXAxis = 0.0f;
  
      float velocityX = 0.0f;
      float velocityY = 0.0f;
  
      // Use this for initialization
      void Start()
      {
          Vector3 angles = transform.eulerAngles;
          rotationYAxis = angles.y;
          rotationXAxis = angles.x;
  
          // Make the rigid body not change rotation
          if (rigidbody)
          {
              rigidbody.freezeRotation = true;
          }
      }
  
      void LateUpdate()
      {
          if (target)
          {
              if (Input.GetMouseButton(1))
              {
                  velocityX += xSpeed * Input.GetAxis("Mouse X") * 0.02f;
                  velocityY += ySpeed * Input.GetAxis("Mouse Y") * 0.02f;
              }
  
              rotationYAxis += velocityX;
              rotationXAxis -= velocityY;
  
              rotationXAxis = ClampAngle(rotationXAxis, yMinLimit, yMaxLimit);
  
              Quaternion fromRotation = Quaternion.Euler(transform.rotation.eulerAngles.x, transform.rotation.eulerAngles.y, 0);
              Quaternion toRotation = Quaternion.Euler(rotationXAxis, rotationYAxis, 0);
              Quaternion rotation = toRotation;
              
              
  
             
              Vector3 negDistance = new Vector3(0.0f, 0.0f, -distance);
              Vector3 position = rotation * negDistance + target.position;
              
              transform.rotation = rotation;
              transform.position = position;
  
              velocityX = Mathf.Lerp(velocityX, 0, Time.deltaTime * smoothTime);
              velocityY = Mathf.Lerp(velocityY, 0, Time.deltaTime * smoothTime);
          }
  
      }
  
      public static float ClampAngle(float angle, float min, float max)
      {
          if (angle < -360F)
              angle += 360F;
          if (angle > 360F)
              angle -= 360F;
          return Mathf.Clamp(angle, min, max);
      }
  }