マウスでカメラ操作を行うスクリプト

MouseCameraController.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class MouseCameraController : MonoBehaviour
{
    [SerializeField]
    private float _speed = 0.1f;

    [SerializeField]
    private float _rotSpeed = 0.1f;

    private Vector2 _prevMovePos;
    private Vector2 _prevRotPos;
    private Vector2 ZERO_VEC2 = Vector2.zero;
    private Transform _targetCamera;

#if UNITY_EDITOR
    private void Start()
    {
        _targetCamera = GetComponent<Camera>().transform;
    }

    private void Update()
    {
        if (Input.GetMouseButton(0))
        {
            Move();
        }

        if (Input.GetMouseButton(1))
        {
            Rotate();
        }

        if (Input.GetMouseButtonUp(0))
        {
            _prevMovePos = ZERO_VEC2;
        }

        if (Input.GetMouseButtonUp(1))
        {
            _prevRotPos = ZERO_VEC2;
        }
    }

    private void Rotate()
    {
        if (_prevRotPos == ZERO_VEC2)
        {
            _prevRotPos = Input.mousePosition;
            return;
        }

        Vector2 current = Input.mousePosition;
        Vector2 vec = (current - _prevRotPos) * _rotSpeed;
        Vector3 euler = transform.rotation.eulerAngles;
        euler.y += vec.x;
        euler.x -= vec.y;
        transform.rotation = Quaternion.Euler(euler);
        _prevRotPos = current;
    }

    private void Move()
    {
        if (_prevMovePos == ZERO_VEC2)
        {
            _prevMovePos = Input.mousePosition;
            return;
        }

        Vector2 current = Input.mousePosition;
        Vector2 speedVec = (current - _prevMovePos) * _speed;
        Vector3 moveVec = (transform.right * speedVec.x) + (transform.up * speedVec.y);
        _targetCamera.position += moveVec;
        _prevMovePos = current;
    }
#endif
}