Merge pull request #155 from NiklasEi/document-system-ordering

Support explicitly ordering against the loading state
NiklasEi · Oct 14, 2023 · a60227c · a60227c
2 parents ccbe379 + 5b2a7ab
commit a60227c
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,7 @@
 # Changelog
 
+- Make `loading_state::LoadingStateSet` public for explicit system ordering
+
 ## v0.17.0
 - update to Bevy 0.11
 - Use "/" in paths used as keys for mapped collections on all platforms (resolves [#135](https://github.com/NiklasEi/bevy_asset_loader/issues/135))

diff --git a/README.md b/README.md
@@ -371,7 +371,7 @@ See [`progress_tracking`](bevy_asset_loader/examples/progress_tracking.rs) for a
 
 ### A note on system ordering
 
-The loading state runs in a base set between `CoreSet::StateTransitions` and `CoreSet::Update`. This means that systems running in `CoreSet::Update` can already see the reported progress of all tracked asset collections for the current frame.
+The loading state is organized in a private schedule that runs in a single system during the `Update` schedule. If you want to explicitly order against the system running the loading state, you can do so with the system set `LoadingStateSet`.
 
 ## Failure state
 

diff --git a/bevy_asset_loader/examples/progress_tracking.rs b/bevy_asset_loader/examples/progress_tracking.rs
@@ -27,13 +27,10 @@ fn main() {
         .add_systems(OnEnter(MyStates::Next), expect)
         .add_systems(
             Update,
-            (
-                track_fake_long_task
-                    .track_progress()
-                    .before(print_progress)
-                    .run_if(in_state(MyStates::AssetLoading)),
-                print_progress,
-            ),
+            (track_fake_long_task.track_progress(), print_progress)
+                .chain()
+                .run_if(in_state(MyStates::AssetLoading))
+                .after(LoadingStateSet(MyStates::AssetLoading)),
         )
         .run();
 }

diff --git a/bevy_asset_loader/src/lib.rs b/bevy_asset_loader/src/lib.rs
@@ -92,7 +92,7 @@ pub mod prelude {
             DynamicAsset, DynamicAssetCollection, DynamicAssetCollections, DynamicAssetType,
             DynamicAssets,
         },
-        loading_state::{LoadingState, LoadingStateAppExt},
+        loading_state::{LoadingState, LoadingStateAppExt, LoadingStateSet},
     };
 }
 

diff --git a/bevy_asset_loader/src/loading_state.rs b/bevy_asset_loader/src/loading_state.rs
@@ -446,7 +446,7 @@ where
 
 ///  Systems in this set check the loading state of assets and will change the [`InternalLoadingState`] accordingly.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, SystemSet)]
-pub(crate) struct LoadingStateSet<S: States>(S);
+pub struct LoadingStateSet<S: States>(pub S);
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, SystemSet)]
 pub(crate) enum InternalLoadingStateSet {

diff --git a/bevy_asset_loader/tests/ui/no_default.stderr b/bevy_asset_loader/tests/ui/no_default.stderr
@@ -5,14 +5,14 @@ error[E0277]: the trait bound `NoDefault: std::default::Default` is not satisfie
   |     ^^^^^^^^^^ the trait `std::default::Default` is not implemented for `NoDefault`
   |
   = help: the following other types implement trait `FromWorld`:
-            BlitPipeline
             CASNode
-            CASPipeline
+            MainPass2dNode
             Children
-            FallbackImage
-            FallbackImageCubemap
-            FallbackImageZero
-            FxaaPipeline
+            Parent
+            SceneLoader
+            MsaaWritebackNode
+            Material2dPipeline<M>
+            BlitPipeline
           and $N others
   = note: required for `NoDefault` to implement `FromWorld`
 help: consider annotating `NoDefault` with `#[derive(Default)]`