SpaceSphere.cs

using System;
using System.Collections;
using System.Reflection;
using UnityEditor;
using UnityEngine;

[InitializeOnLoad]
class SpaceSphere
{
  static SpaceSphere()
  {
    // OnGlobalEventHandler
    // from http://anchan828.hatenablog.jp/entry/2013/12/29/015306
    EditorApplication.CallbackFunction function = () => OnGlobalEventHandler (Event.current);
    FieldInfo info = typeof(EditorApplication).GetField ("globalEventHandler", BindingFlags.Static | BindingFlags.Instance | BindingFlags.NonPublic);
    EditorApplication.CallbackFunction functions = (EditorApplication.CallbackFunction)info.GetValue (null);
    functions += function;
    info.SetValue (null, (object)functions);
  }

  private static bool pressed;
  private static Tool saved;
  public static void OnGlobalEventHandler(Event e)
  {
    if (!pressed && e.type == EventType.keyDown)
    {
      if(e.keyCode == KeyCode.Space)
      {
        pressed = true;
        saved = Tools.current;
        Tools.current = Tool.View;
      }
    }
    if (pressed && e.type == EventType.keyUp)
    {
      if(e.keyCode == KeyCode.Space)
      {
        pressed = false;
        Tools.current = saved;
      }
    }
  }
}