我最近安装了 panda3d 版本 1.8.1，它被称为最新的稳定版本。但是当我从 direct.showbase.ShowBase import ShowBase 键入以下代码时
class MyApp(ShowBase):
def __init__(self):
ShowBase.__init__(self)
app = MyApp()
app.run()
上面的代码生成了以下错误消息：
:ShowBase(warning): Unable to open 'onscreen' window.
Traceback (most recent call last):
File "D:\delme.py", line 8, in <module>
app = MyApp()
File "D:\delme.py", line 6, in __init__
ShowBase.__init__(self)
File "C:\Panda3D-1.8.1\direct\showbase\ShowBase.py", line 244, in __init__
self.openDefaultWindow(startDirect = False, props=props)
File "C:\Panda3D-1.8.1\direct\showbase\ShowBase.py", line 880, in openDefaultWindow
self.openMainWindow(*args, **kw)
File "C:\Panda3D-1.8.1\direct\showbase\ShowBase.py", line 916, in openMainWindow
self.openWindow(*args, **kw)
File "C:\Panda3D-1.8.1\direct\showbase\ShowBase.py", line 671, in openWindow
raise StandardError, 'Could not open window.'
StandardError: Could not open window.
任何想法为什么会发生这种情况，我该如何解决？