>>> pane = hou.ui.curDesktop().paneTabOfType(hou.paneTabType.SceneViewer)
<hou.SceneViewer panetab1>
>>> settings = pane.curViewport().settings()
<hou.GeometryViewportSettings>
None
cam1
0.40000000596
>>> settings.setViewMaskOpacity(1)
>>> mycam = hou.node("/obj/cam1")
cam1
>>> settings.setCamera(mycam)
>>> def_cam = cam = viewport.defaultCamera()
Traceback (most recent call last):
  File "<console>", line 1, in <module>
NameError: name 'viewport' is not defined
>>> defcam = settings.defaultCamera()
Traceback (most recent call last):
  File "<console>", line 1, in <module>
AttributeError: 'GeometryViewportSettings' object has no attribute 'defaultCamera'
>>> print pane.curViewport()
<hou.GeometryViewport persp1 of type Perspective>

import hou
from PySide2 import QtCore, QtUiTools, QtWidgets
 
class classname(QtWidgets.QWidget):
    def __init__(self):
        super(classname,self).__init__()        
        self.ui = QtUiTools.QUiLoader().load(ui_path, parentWidget=self)
        self.setParent(hou.ui.mainQtWindow(), QtCore.Qt.Window)
 
win = classname()
win.show()

• python 2715 / pip 9.0.3