Support a run condition on SpritesheetAnimationPlugin to allow pausing animations

[mgi388]

The play animation system always runs:

bevy_spritesheet_animation/src/plugin.rs

Line 75 in bf5861f

spritesheet_animation::play_animations.in_set(AnimationSystemSet),

This means if your app wants to pause animations, e.g. when the player presses Pause, the app would have to iterate all animations and pause them itself.

I think it would be better if the plugin received a run_if condition which can be used to determine if the animation system should run. I'd use this to pass run_if(in_state(Unpaused)) to the plugin.

I imagine the implementation would look similar to this: https://github.com/jakobhellermann/bevy-inspector-egui/blob/eaf1ec72819d82254b8de9236246450d86dd2bc1/crates/bevy-inspector-egui/src/quick.rs#L71

WDYT?

[merwaaan]

Absolutely, there's no quick way to pause all the animations at the moment.

We could have a "global" running flag accessible from somewhere. Maybe in AnimationLibrary since it's the main plugin resource.

But your idea of using the built-in run_if predicate seems more Bevy-like. Let's go in that direction.

PR welcome :)
(otherwise I'll take a look whenever I get a chance, but that won't be in the next days)

[mgi388]

I'll need to check if a run condition is the correct way to do this. I just saw https://github.com/bevyengine/bevy/blob/6659f37df1522fd2f927b2afb28ce779cfe3c999/examples/time/virtual_time.rs#L171-L177 and it seems like maybe using VirtualTime could be the correct approach here. Not sure what happens if you want to have some animations working while paused, and some not working. I also need to check how bevy_animation supports or doesn't support this because I'd imagine that bevy_spritesheet_animation should do the same thing.