Friday, 11 January 2013

SceneRestoreContext context manager for your viewports

Thought I'd breifly go through the SceneRestoreContext manager in the Red9.General module as it's something that came up today at work. So what is it, well it's a context manager that 's designed to store, and restore all your viewport settings including:

  • all viewport display options and shading states(for all 4 modelPanels)
  • playbackOptions including units, times, timeranges and settings 
  • scene units
  • current audio set in the timeline and it's active state
  • current main camera settings (tranforms)
  • cameras active in all the modelPanels 

Basically just about everything there is that makes that current session look as it does. Why?? Well sometimes when you're processing data you want to do things to the scene which you really want to restore afterwards. Lets say you're batching a ton of anim data, opening files, switching cameras etc and at the end of processing you want the scene to be set back to how it was. Now this isn't a scene load, this is a cache of all the main ui element settings.

This can be run in 2 ways, the best is to use it as designed, as a context manager:

import Red9_General as r9Gen
with r9Gen.SceneRestoreContext:
    do your code here

Now anybody who's used context managers in Python will get the syntax here. The 'with' is doing all the work for you. On entering the call it runs the internal __enter__ call, then runs everything inside the tab (your code), then when complete runs the internal __exit__ call. The great thing about context managers is that even if your code bombs, the __exit__ will still get called and the scene restored to it's cached state.

You can of course use it as you want, so you can take an instance of the object, run the store then when you need to, run the restore:


do your code here


it's just a function call at the end of the day and might prove useful to others whilst designing tools. If you find anything that you think this is not catching let me know. There's also an AnimationContext thats used in all the animation tools and a HIKContext for managing the set state of HIK rig nodes.