Unityのカメラ用スクリプト。Sceneビューのようなマウス操作でカメラを移動可能にする。

SceneViewCamera.cs

using UnityEngine;

/// <summary>
/// GameビューにてSceneビューのようなカメラの動きをマウス操作によって実現する
/// </summary>
[RequireComponent(typeof(Camera))]
public class SceneViewCamera : MonoBehaviour
{
  [SerializeField, Range(0.1f, 10f)]
  private float wheelSpeed = 1f;

  [SerializeField, Range(0.1f, 10f)]
  private float moveSpeed = 0.3f;

  [SerializeField, Range(0.1f, 10f)]
  private float rotateSpeed = 0.3f;

  private Vector3 preMousePos;

  private void Update()
  {
    MouseUpdate();
    return;
  }

  private void MouseUpdate()
  {
    float scrollWheel = Input.GetAxis("Mouse ScrollWheel");
    if(scrollWheel != 0.0f)
      MouseWheel(scrollWheel);

    if(Input.GetMouseButtonDown(0) ||
       Input.GetMouseButtonDown(1) ||
       Input.GetMouseButtonDown(2))
      preMousePos = Input.mousePosition;

    MouseDrag(Input.mousePosition);
  }

  private void MouseWheel(float delta)
  {
    transform.position += transform.forward * delta * wheelSpeed;
    return;
  }

  private void MouseDrag(Vector3 mousePos)
  {
    Vector3 diff = mousePos - preMousePos;

    if(diff.magnitude < Vector3.kEpsilon)
      return;

    if(Input.GetMouseButton(2))
      transform.Translate(-diff * Time.deltaTime * moveSpeed);
    else if(Input.GetMouseButton(1))
      CameraRotate(new Vector2(-diff.y, diff.x) * rotateSpeed);

    preMousePos = mousePos;
  }

  public void CameraRotate(Vector2 angle)
  {
    transform.RotateAround(transform.position, transform.right, angle.x);
    transform.RotateAround(transform.position, Vector3.up, angle.y);
  }
}