caching render objects safely

[Vaendryl]

I was thinking that maybe showing a lot of displaybles on screen could be sped up by storing a render object inside the displayable instance and have the render method return that if nothing's changed, or maybe store a couple of different renders and just return the one that's needed rather than rerender one each frame.

example:

Code: Select all

    class CachingDisplayable(renpy.Displayable):
        def __init__(self, child, **kwargs):
            super(CachingDisplayable, self).__init__(**kwargs)
            self.child = child
            self.render_cache = None
        
        def render(self, width, height, st, at):
            if self.render_cache is not None:
                self.render_cache = renpy.render(self.child, width, height, st, at)            
            return self.render_cache

obviously, the main issue that comes to mind right away is that render objects can't be pickled. any save routine would have to be updated to purge the cache of all displayables, but that should be possible in theory.

anyone know if going to these lengths has any value? I'm not even sure if ren'py already does this internally making it unlikely there'd be any gains.

there also seems to be an issue where cached renders turn completely black when the game window changes size or switches to full screen mode. anyone know anything about this? are there triggers I can use to purge the caches when the user changes the window size?

[PyTom]

Ren'Py does cache it internally, and clears the cache appropriately. So there's not much benefit from doing it yourself, and you've hit the problems.

[Vaendryl]

thanks for the answer, man.

main advantage I'd hope to get was to not just cache a single render but multiple, basically caching a simple animation. I don't suppose you've got any ideas about that?

[PyTom]

That should work provided you set st and at correctly.