[Merged by Bors] - Added Ref to allow immutable access with change detection #7097

Guvante · 2023-01-05T18:25:50Z

Objective

Fixes Suggestion: A variant of ChangeTrackers that also allows access to the component #7066

Solution

Split the ChangeDetection trait into ChangeDetection and ChangeDetectionMut
Added Ref as equivalent to &T with change detection

Changelog

Support for Ref which allow inspecting change detection flags in an immutable way

Migration Guide

While bevy prelude includes both ChangeDetection and ChangeDetectionMut any code explicitly referencing ChangeDetection might need to be updated to ChangeDetectionMut or both. Specifically any reading logic requires ChangeDetection while writes requires ChangeDetectionMut.

use bevy_ecs::change_detection::DetectChanges -> use bevy_ecs::change_detection::{DetectChanges, DetectChangesMut}

Previously Res had methods to access change detection is_changed and is_added those methods have been moved to the DetectChanges trait. If you are including bevy prelude you will have access to these types otherwise you will need to use bevy_ecs::change_detection::DetectChanges to continue using them.

Guvante · 2023-01-05T18:28:52Z

I did not implement ResRef's SystemParam trait because I wanted feedback on this implementation. Most notably I wanted to ensure that the splitting of the ChangeDetection trait was a worthwhile breaking change.

crates/bevy_ecs/src/change_detection.rs

mockersf · 2023-01-06T00:50:24Z

A long time ago, this existed: https://docs.rs/bevy/0.4.0/bevy/ecs/struct.Ref.html. I think it was removed in the ecs rewrite in 0.5.

Guvante · 2023-01-06T01:45:49Z

Ref<'a, T> was what is now covered by &'a T directly. This simply reintroduces it to cover when you need access to change tracking information. (I totally chose the name based on that one though)

alice-i-cecile · 2023-01-06T02:00:15Z

I definitely think Ref is the right name here: there's a clear parallel with Mut.

alice-i-cecile · 2023-01-06T02:15:46Z

crates/bevy_ecs/src/change_detection.rs

@@ -81,6 +62,46 @@ pub trait DetectChanges {
    /// [`SystemChangeTick`](crate::system::SystemChangeTick)
    /// [`SystemParam`](crate::system::SystemParam).
    fn last_changed(&self) -> u32;
+}
+
+/// Types that implement reliable change detection.


This description feels too broad: this is only for the Mut form.

All of this is unchanged, git just got confused because I put the new DetectChanges first.

alice-i-cecile · 2023-01-06T02:16:18Z

crates/bevy_ecs/src/change_detection.rs

@@ -284,6 +336,26 @@ impl<'a> Ticks<'a> {
    }
 }

+/// Shared borrow of an entity's component with change tracking metadata


Needs links to explain "change tracking metadata" in these docs.

There is no such documentation. I can point over to DetectChangesMut though.

Yeah, that sounds reasonable. We should probably have module level docs here, but that can wait for its own PR.

I think it should be rephrased with less jargon. Something like "Shared borrow of an entity's component that gives access to change detection."

alice-i-cecile

Generally looks good. The split between DetectChanges and DetectChangesMut definitely feels conceptually correct to me.

Needs more docs and cross-references: this is tricky and fairly arcane code.

alice-i-cecile · 2023-01-06T02:20:20Z

crates/bevy_ecs/src/change_detection.rs

@@ -28,15 +28,6 @@ pub const MAX_CHANGE_AGE: u32 = u32::MAX - (2 * CHECK_TICK_THRESHOLD - 1);
 /// ## Example
 /// Using types that implement [`DetectChanges`], such as [`ResMut`], provide
 /// a way to query if a value has been mutated in another system.
-/// Normally change detecting is triggered by either [`DerefMut`] or [`AsMut`], however


This explanation was very useful, we either need to keep it or link to DetectChangeMut.

I didn't think explaining how to bypass change detection on a type that can't cause change detection was the right location.

Yeah, I agree there! But we should link to the subtrait in these docs: it's hard discover them otherwise.

I also think that mentioning that "change detection works via DerefMut" is important information.

I think there is a comment pointing towards DetectChangesMut now to point that (I used ResMut as an example too)

crates/bevy_ecs/src/change_detection.rs

JoJoJet · 2023-01-06T05:05:15Z

I definitely think Ref is the right name here: there's a clear parallel with Mut.

I don't necessarily disagree, but I want to note that these aren't exactly comparable. Mut<T> is a wrapper type that automagically replaces &mut T when used in a worldquery, whereas Ref<T> is a type that you'd have to explicitly name. This makes the name feel more arbitrary IMO, but I am pending a better suggestion.

Guvante · 2023-01-06T06:15:18Z

I am fine with renaming Ref, I only chose it since I remembered that was what it used to be called.

Side note I moved Res into change_detection, it doesn't impact anything (ResMut has been there since before this PR) but it allowed me to steal the macros.

Also I made Res use Ticks in a previous commit. Both changes aren't important but they felt right from a consistency standpoint.

alice-i-cecile · 2023-01-06T16:19:05Z

Both changes aren't important but they felt right from a consistency standpoint.

I agree with this.

JoJoJet

The implementation looks solid all around. The addition of Ref<> will definitely be useful, I always get bitten by having to include both &T and ChangeTrackers<T> in the same query.

I'm not sure about the DetectChanges split, though. I don't know how useful a read-only variant of that trait will be, and having to write DetectChangesMut everywhere is an unfortunate UX loss.

Guvante · 2023-01-07T00:42:21Z

Should I leave DetectChanges as a mut thing and make the other methods not be based on a trait? I guess that matches the current.

It felt a little arbitrary but if it is better UX I am fine with it.

JoJoJet · 2023-01-07T00:57:59Z

That's my personal preference, but you can wait for other opinions if you want, of course.

james7132 · 2023-01-07T01:18:38Z

Doesn't this make ChangeTrackers obsolete? The current access model cannot differentiate between a change tick read and a component read, and the compiler will optimize out the unused reference, so I don't see a reason why we need ChangeTrackers<T> when we have Ref<T>.

james7132

Implementation generally looks solid. LGTM. I think the trait split makes sense, and could see some use as a generic constraint in both cases.

We should have a followup PR that changes some of the uses of ChangeTrackers<T> in combination with &T queries to use this instead.

alice-i-cecile

This looks good now, I like this trait split.

Unsure about removing ChangeTrackers, but that should be discussed elsewhere.

alice-i-cecile · 2023-01-09T21:25:04Z

bors r+

# Objective - Fixes #7066 ## Solution - Split the ChangeDetection trait into ChangeDetection and ChangeDetectionMut - Added Ref as equivalent to &T with change detection --- ## Changelog - Support for Ref which allow inspecting change detection flags in an immutable way ## Migration Guide - While bevy prelude includes both ChangeDetection and ChangeDetectionMut any code explicitly referencing ChangeDetection might need to be updated to ChangeDetectionMut or both. Specifically any reading logic requires ChangeDetection while writes requires ChangeDetectionMut. use bevy_ecs::change_detection::DetectChanges -> use bevy_ecs::change_detection::{DetectChanges, DetectChangesMut} - Previously Res had methods to access change detection `is_changed` and `is_added` those methods have been moved to the `DetectChanges` trait. If you are including bevy prelude you will have access to these types otherwise you will need to `use bevy_ecs::change_detection::DetectChanges` to continue using them.

alice-i-cecile · 2023-01-10T22:53:41Z

bors r+

# Objective - Fixes #7066 ## Solution - Split the ChangeDetection trait into ChangeDetection and ChangeDetectionMut - Added Ref as equivalent to &T with change detection --- ## Changelog - Support for Ref which allow inspecting change detection flags in an immutable way ## Migration Guide - While bevy prelude includes both ChangeDetection and ChangeDetectionMut any code explicitly referencing ChangeDetection might need to be updated to ChangeDetectionMut or both. Specifically any reading logic requires ChangeDetection while writes requires ChangeDetectionMut. use bevy_ecs::change_detection::DetectChanges -> use bevy_ecs::change_detection::{DetectChanges, DetectChangesMut} - Previously Res had methods to access change detection `is_changed` and `is_added` those methods have been moved to the `DetectChanges` trait. If you are including bevy prelude you will have access to these types otherwise you will need to `use bevy_ecs::change_detection::DetectChanges` to continue using them.

bors · 2023-01-10T23:05:36Z

Build failed:

run-examples-on-wasm

- Moved Res to near ResMut in file structure - Ref formated similar to Res - Split DetectChanges to make DetectChangesMut - Created Ticks and renamed TicksMut - Standardized usage of DetectChanges and Ticks in Res/Ref

…omment after = makes no sense to me)

…ight' way

…ed now

james7132 · 2023-01-11T15:41:29Z

bors retry

# Objective - Fixes #7066 ## Solution - Split the ChangeDetection trait into ChangeDetection and ChangeDetectionMut - Added Ref as equivalent to &T with change detection --- ## Changelog - Support for Ref which allow inspecting change detection flags in an immutable way ## Migration Guide - While bevy prelude includes both ChangeDetection and ChangeDetectionMut any code explicitly referencing ChangeDetection might need to be updated to ChangeDetectionMut or both. Specifically any reading logic requires ChangeDetection while writes requires ChangeDetectionMut. use bevy_ecs::change_detection::DetectChanges -> use bevy_ecs::change_detection::{DetectChanges, DetectChangesMut} - Previously Res had methods to access change detection `is_changed` and `is_added` those methods have been moved to the `DetectChanges` trait. If you are including bevy prelude you will have access to these types otherwise you will need to `use bevy_ecs::change_detection::DetectChanges` to continue using them.

bors · 2023-01-11T16:02:07Z

Pull request successfully merged into main.

Build succeeded:

# Objective Follow up #7097. Use `Ref<T>` instead of `&T` and the change detection query params. ## Solution Replace them.

…#7097) # Objective - Fixes bevyengine#7066 ## Solution - Split the ChangeDetection trait into ChangeDetection and ChangeDetectionMut - Added Ref as equivalent to &T with change detection --- ## Changelog - Support for Ref which allow inspecting change detection flags in an immutable way ## Migration Guide - While bevy prelude includes both ChangeDetection and ChangeDetectionMut any code explicitly referencing ChangeDetection might need to be updated to ChangeDetectionMut or both. Specifically any reading logic requires ChangeDetection while writes requires ChangeDetectionMut. use bevy_ecs::change_detection::DetectChanges -> use bevy_ecs::change_detection::{DetectChanges, DetectChangesMut} - Previously Res had methods to access change detection `is_changed` and `is_added` those methods have been moved to the `DetectChanges` trait. If you are including bevy prelude you will have access to these types otherwise you will need to `use bevy_ecs::change_detection::DetectChanges` to continue using them.

# Objective Follow up bevyengine#7097. Use `Ref<T>` instead of `&T` and the change detection query params. ## Solution Replace them.

# Objective Add the change-detection wrapper type `Ref<T>` (originally added in #7097) to `bevy_ecs::prelude`.

…#7097) # Objective - Fixes bevyengine#7066 ## Solution - Split the ChangeDetection trait into ChangeDetection and ChangeDetectionMut - Added Ref as equivalent to &T with change detection --- ## Changelog - Support for Ref which allow inspecting change detection flags in an immutable way ## Migration Guide - While bevy prelude includes both ChangeDetection and ChangeDetectionMut any code explicitly referencing ChangeDetection might need to be updated to ChangeDetectionMut or both. Specifically any reading logic requires ChangeDetection while writes requires ChangeDetectionMut. use bevy_ecs::change_detection::DetectChanges -> use bevy_ecs::change_detection::{DetectChanges, DetectChangesMut} - Previously Res had methods to access change detection `is_changed` and `is_added` those methods have been moved to the `DetectChanges` trait. If you are including bevy prelude you will have access to these types otherwise you will need to `use bevy_ecs::change_detection::DetectChanges` to continue using them.

# Objective Follow up bevyengine#7097. Use `Ref<T>` instead of `&T` and the change detection query params. ## Solution Replace them.

# Objective Add the change-detection wrapper type `Ref<T>` (originally added in bevyengine#7097) to `bevy_ecs::prelude`.

# Objective `ChangeTrackers<>` is a `WorldQuery` type that lets you access the change ticks for a component. #7097 has added `Ref<>`, which gives access to a component's value in addition to its change ticks. Since bevy's access model does not separate a component's value from its change ticks, there is no benefit to using `ChangeTrackers<T>` over `Ref<T>`. ## Solution Deprecate `ChangeTrackers<>`. --- ## Changelog * `ChangeTrackers<T>` has been deprecated. It will be removed in Bevy 0.11. ## Migration Guide `ChangeTrackers<T>` has been deprecated, and will be removed in the next release. Any usage should be replaced with `Ref<T>`. ```rust // Before (0.9) fn my_system(q: Query<(&MyComponent, ChangeTrackers<MyComponent>)>) { for (value, trackers) in &q { if trackers.is_changed() { // Do something with `value`. } } } // After (0.10) fn my_system(q: Query<Ref<MyComponent>>) { for value in &q { if value.is_changed() { // Do something with `value`. } } } ```

@cart

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If you think we missed something (or didn't prioritize something appropriately), let us know. * ECS Schedule v3 (previously known as "stageless") * Partial Android Support * Depth and Normal Prepass * Environment Map Lighting * Cascaded Shadow Maps * Distance and Atmospheric Fog * Smooth Skeletal Animation Transitions * Enable Parallel Pipelined Rendering * Windows as Entities * Renderer Optimizations * ECS Optimizations ## Sections These are the sections we will cover in the blog post. If a section has been claimed, it will have `(claimed by X)` in the title. If it is unclaimed it will have `(unclaimed)` in the title. Let us know if we missed a section. We don't cover every feature, but we should cover pretty much everything that would be interesting to users. Note that what is interesting or challenging to implement is not necessarily something that is relevant to our blog post readers. And sometimes the reverse is true! If you believe a section should be split up or reorganized, just bring it up here and we can discuss it. ### ~~Schedule V3 (claimed by @alice-i-cecile)~~ * [Migrate engine to Schedule v3][7267] * [Add `bevy_ecs::schedule_v3` module][6587] * [Stageless: fix unapplied systems][7446] * [Stageless: move final apply outside of spawned executor][7445] * Sets * Base Sets * [Base Sets][7466] * Reporting * [Report sets][7756] * [beter cycle reporting][7463] * Run Conditions * [Add condition negation][7559] * [And/Or][7605] * [Add more common run conditions][7579] * States * [States derive macro][7535] * System Piping Flexibility * [Support piping exclusive systems][7023] * [Allow piping run conditions][7547] ### ~~Depth and Normal Prepass (claimed by @IceSentry)~~ * [Add depth and normal prepass][6284] * [Move prepass functions to prepass_utils][7354] ### ~~Distance and Atmospheric Fog (claimed by @coreh)~~ * [Add Distance and Atmospheric Fog support][6412] ### ~~Cascaded Shadow Maps (claimed by @cart)~~ * [Cascaded shadow maps.][7064] * [Better cascades config defaults + builder, tweak example configs][7456] ### ~~Environment Map Lighting (claimed by @cart)~~ * [EnvironmentMapLight, BRDF Improvements][7051] * [Webgl2 support][7737] ### ~~Tonemapping options (claimed by @cart)~~ * [Initial tonemapping options][7594] ### ~~Android support + unification (claimed by @mockersf)~~ * [IOS, Android... same thing][7493] ### ~~Windows as Entities (claimed by @Aceeri)~~ * [Windows as Entities][5589] * [break feedback loop when moving cursor][7298] * [Fix `Window` feedback loop between the OS and Bevy][7517] ### ~~Enable Parallel Pipelined Rendering (claimed by @james7132)~~ * [Pipelined Rendering][6503] * [Stageless: add a method to scope to always run a task on the scope thread][7415] * [Separate Extract from Sub App Schedule][7046] ### ~~Smooth Skeletal Animation Transitions (claimed by @james7132)~~ * [Smooth Transition between Animations][6922] ### ~~Spatial Audio (claimed by @harudagondi)~~ * [Spatial Audio][6028] ### ~~Shader Processor Features (claimed by @cart)~~ * [Shader defs can now have a value][5900] * [Shaders can now have #else ifdef chains][7431] * [Define shader defs in shader][7518] ### ~~Shader Flexibility Improvements (claimed by @cart)~~ * [add ambient lighting hook][5428] * [Refactor Globals and View structs into separate shaders][7512] ### ~~Renderer Optimizations (claimed by @james7132)~~ * [bevy_pbr: Avoid copying structs and using registers in shaders][7069] * [Flatten render commands][6885] * [Replace UUID based IDs with a atomic-counted ones][6988] * [improve compile time by type-erasing wgpu structs][5950] * [Shrink DrawFunctionId][6944] * [Shrink ComputedVisibility][6305] * [Reduce branching in TrackedRenderPass][7053] * [Make PipelineCache internally mutable.][7205] * [Improve `Color::hex` performance][6940] * [Support recording multiple CommandBuffers in RenderContext][7248] * [Parallelized transform propagation][4775] * [Introduce detailed_trace macro, use in TrackedRenderPass][7639] * [Optimize color computation in prepare_uinodes][7311] * [Directly extract joints into SkinnedMeshJoints][6833] * [Parallelize forward kinematics animation systems][6785] * [Move system_commands spans into apply_buffers][6900] * [Reduce the use of atomics in the render phase][7084] ### ~~ECS Optimizations (claimed by @james7132 )~~ * [Remove redundant table and sparse set component IDs from Archetype][4927] * [Immutable sparse sets for metadata storage][4928] * [Replace BlobVec's swap_scratch with a swap_nonoverlapping][4853] * [Use T::Storage::STORAGE_TYPE to optimize out unused branches][6800] * [Remove unnecessary branching from bundle insertion][6902] * [Split Component Ticks][6547] * [use bevy_utils::HashMap for better performance. TypeId is predefined …][7642] * [Extend EntityLocation with TableId and TableRow][6681] * [Basic adaptive batching for parallel quer- [Speed up `CommandQueue` by storing commands more densely][6391]y iteration][4777] ### ~~Reflect Improvements (claimed by @cart)~~ * [bevy_reflect: Add `ReflectFromReflect` (v2)][6245] * [Add reflection support for VecDeque][6831] * [reflect: add `insert` and `remove` methods to `List`][7063] * [Add `remove` method to `Map` reflection trait.][6564] * [bevy_reflect: Fix binary deserialization not working for unit structs][6722] * [Add `TypeRegistrationDeserializer` and remove `BorrowedStr`][7094] * [bevy_reflect: Add simple enum support to reflection paths][6560] * [Enable deriving Reflect on structs with generic types][7364] * [bevy_reflect: Support tuple reflection paths][7324] * [bevy_reflect: Pre-parsed paths][7321] * [bevy_ecs: ReflectComponentFns without World][7206] ### ~~AsBindGroup Improvements (claimed by @cart)~~ * [Support storage buffers in derive `AsBindGroup`][6129] * [Support raw buffers in AsBindGroup][7701] ### ~~Cylinder Shape (claimed by @cart)~~ * [Add cylinder shape][6809] ### ~~Subdividable Plane Shape (claimed by @cart)~~ * [added subdivisions to shape::Plane][7546] ### ~~StandardMaterial Blend Modes (claimed by @coreh)~~ * [Standard Material Blend Modes][6644] ### ~~Configurable Visibility Component (claimed by @cart)~~ * [enum `Visibility` component][6320] ### Task Improvements (claimed by @cart) * [Fix panicking on another scope][6524] * [Add thread create/destroy callbacks to TaskPool][6561] * [Thread executor for running tasks on specific threads.][7087] * [await tasks to cancel][6696] * [Stageless: move MainThreadExecutor to schedule_v3][7444] * [Stageless: close the finish channel so executor doesn't deadlock][7448] ### ~~Upgrade to wgpu 0.15 (claimed by @cart)~~ * [Wgpu 0.15][7356] ### ~~Expose Bindless / Non-uniform Indexing Support (claimed by @cart)~~ * [Request WGPU Capabilities for Non-uniform Indexing][6995] ### ~~Cubic Spline (claimed by @aevyrie)~~ * [Bezier][7653] ### ~~Revamp Bloom (claimed by @JMS55)~~ * [Revamp bloom](bevyengine/bevy#6677) ### ~~Use Prepass Shaders for Shadows (claimed by @superdump)~~ * [use prepass shaders for shadows](bevyengine/bevy#7784) ### ~~AccessKit (claimed by @alice-i-cecile)~~ * [accesskit](bevyengine/bevy#6874) ### ~~Camera Output Modes (claimed by @cart)~~ * [camera output modes](bevyengine/bevy#7671) ### ~~SystemParam Improvements (claimed by @JoJoJet)~~ * [Make the `SystemParam` derive macro more flexible][6694] * [Add a `SystemParam` primitive for deferred mutations; allow `#[derive]`ing more types of SystemParam][6817] ### ~~Gamepad Improvements (claimed by @cart)~~ * [Gamepad events refactor][6965] * [add `Axis::devices` to get all the input devices][5400] ### ~~Input Methods (claimed by @cart)~~ * [add Input Method Editor support][7325] ### ~~Color Improvements (claimed by @cart)~~ * [Add LCH(ab) color space to `bevy_render::color::Color`][7483] * [Add a more familiar hex color entry][7060] ### ~~Split Up CorePlugin (claimed by @cart)~~ * [Break `CorePlugin` into `TaskPoolPlugin`, `TypeRegistrationPlugin`, `FrameCountPlugin`.][7083] ### ~~ExtractComponent Derive (claimed by @cart)~~ * [Extract component derive][7399] ### ~~Added OpenGL and DX11 Backends By Default (claimed by @cart)~~ * [add OpenGL and DX11 backends][7481] ### ~~UnsafeWorldCell (claimed by @BoxyUwU)~~ * [Move all logic to `UnsafeWorldCell`][7381] * [Rename `UnsafeWorldCellEntityRef` to `UnsafeEntityCell`][7568] ### ~~Entity Commands (claimed by @cart)~~ * [Add a trait for commands that run for a given `Entity`][7015] * [Add an extension trait to `EntityCommands` to update hierarchy while preserving `GlobalTransform`][7024] * [Add ReplaceChildren and ClearChildren EntityCommands][6035] ### ~~Iterate EntityRef (claimed by @james7132)~~ * [Allow iterating over with EntityRef over the entire World][6843] ### ~~Ref Queries (@JoJoJet)~~ * [Added Ref to allow immutable access with change detection][7097] ### ~~Taffy Upgrade (claimed by @cart)~~ * [Upgrade to Taffy 0.2][6743] ### ~~Relative Cursor Position (claimed by @cart)~~ * [Relative cursor position][7199] ### ~~Const UI Config (claimed by @cart)~~ * [Add const to methods and const defaults to bevy_ui][5542] ### ~~Examples (claimed by @cart)~~ * [Add pixelated Bevy to assets and an example][6408] * [Organized scene_viewer into plugins for reuse and organization][6936] ### ~~CI Improvements (claimed by @cart)~~ * [add rust-version for MSRV and CI job to check][6852] * [msrv: only send a message on failure during the actual msrv part][7532] * [Make CI friendlier][7398] * [Fix CI welcome message][7428] * [add an action to ask for a migration guide when one is missing][7507] ### ~~SMEs (@cart)~~ This was already covered in another blog post. Just briefly call out what they are and that this is the first release that used them. Link to the other blog post. * [Subject Matter Experts and new Bevy Org docs][7185] [4775]: bevyengine/bevy#4775 [4777]: bevyengine/bevy#4777 [4853]: bevyengine/bevy#4853 [4927]: bevyengine/bevy#4927 [4928]: bevyengine/bevy#4928 [5400]: bevyengine/bevy#5400 [5428]: bevyengine/bevy#5428 [5542]: bevyengine/bevy#5542 [5589]: bevyengine/bevy#5589 [5900]: bevyengine/bevy#5900 [5950]: bevyengine/bevy#5950 [6028]: bevyengine/bevy#6028 [6035]: bevyengine/bevy#6035 [6129]: bevyengine/bevy#6129 [6179]: bevyengine/bevy#6179 [6245]: bevyengine/bevy#6245 [6284]: bevyengine/bevy#6284 [6305]: bevyengine/bevy#6305 [6320]: bevyengine/bevy#6320 [6391]: bevyengine/bevy#6391 [6408]: bevyengine/bevy#6408 [6412]: bevyengine/bevy#6412 [6503]: bevyengine/bevy#6503 [6524]: bevyengine/bevy#6524 [6547]: bevyengine/bevy#6547 [6557]: bevyengine/bevy#6557 [6560]: bevyengine/bevy#6560 [6561]: bevyengine/bevy#6561 [6564]: bevyengine/bevy#6564 [6587]: bevyengine/bevy#6587 [6644]: bevyengine/bevy#6644 [6649]: bevyengine/bevy#6649 [6681]: bevyengine/bevy#6681 [6694]: bevyengine/bevy#6694 [6696]: bevyengine/bevy#6696 [6722]: bevyengine/bevy#6722 [6743]: bevyengine/bevy#6743 [6785]: bevyengine/bevy#6785 [6800]: bevyengine/bevy#6800 [6802]: bevyengine/bevy#6802 [6809]: bevyengine/bevy#6809 [6817]: bevyengine/bevy#6817 [6831]: bevyengine/bevy#6831 [6833]: bevyengine/bevy#6833 [6843]: bevyengine/bevy#6843 [6852]: bevyengine/bevy#6852 [6885]: bevyengine/bevy#6885 [6900]: bevyengine/bevy#6900 [6902]: bevyengine/bevy#6902 [6922]: bevyengine/bevy#6922 [6926]: bevyengine/bevy#6926 [6936]: bevyengine/bevy#6936 [6940]: bevyengine/bevy#6940 [6944]: bevyengine/bevy#6944 [6965]: bevyengine/bevy#6965 [6988]: bevyengine/bevy#6988 [6995]: bevyengine/bevy#6995 [7015]: bevyengine/bevy#7015 [7023]: bevyengine/bevy#7023 [7024]: bevyengine/bevy#7024 [7046]: bevyengine/bevy#7046 [7051]: bevyengine/bevy#7051 [7053]: bevyengine/bevy#7053 [7060]: bevyengine/bevy#7060 [7063]: bevyengine/bevy#7063 [7064]: bevyengine/bevy#7064 [7069]: bevyengine/bevy#7069 [7083]: bevyengine/bevy#7083 [7084]: bevyengine/bevy#7084 [7087]: bevyengine/bevy#7087 [7094]: bevyengine/bevy#7094 [7097]: bevyengine/bevy#7097 [7185]: bevyengine/bevy#7185 [7199]: bevyengine/bevy#7199 [7205]: bevyengine/bevy#7205 [7206]: bevyengine/bevy#7206 [7248]: bevyengine/bevy#7248 [7267]: bevyengine/bevy#7267 [7298]: bevyengine/bevy#7298 [7311]: bevyengine/bevy#7311 [7321]: bevyengine/bevy#7321 [7324]: bevyengine/bevy#7324 [7325]: bevyengine/bevy#7325 [7354]: bevyengine/bevy#7354 [7356]: bevyengine/bevy#7356 [7364]: bevyengine/bevy#7364 [7381]: bevyengine/bevy#7381 [7398]: bevyengine/bevy#7398 [7399]: bevyengine/bevy#7399 [7415]: bevyengine/bevy#7415 [7428]: bevyengine/bevy#7428 [7431]: bevyengine/bevy#7431 [7444]: bevyengine/bevy#7444 [7445]: bevyengine/bevy#7445 [7446]: bevyengine/bevy#7446 [7448]: bevyengine/bevy#7448 [7456]: bevyengine/bevy#7456 [7463]: bevyengine/bevy#7463 [7466]: bevyengine/bevy#7466 [7481]: bevyengine/bevy#7481 [7483]: bevyengine/bevy#7483 [7493]: bevyengine/bevy#7493 [7507]: bevyengine/bevy#7507 [7510]: bevyengine/bevy#7510 [7512]: bevyengine/bevy#7512 [7517]: bevyengine/bevy#7517 [7518]: bevyengine/bevy#7518 [7532]: bevyengine/bevy#7532 [7535]: bevyengine/bevy#7535 [7546]: bevyengine/bevy#7546 [7547]: bevyengine/bevy#7547 [7559]: bevyengine/bevy#7559 [7568]: bevyengine/bevy#7568 [7579]: bevyengine/bevy#7579 [7594]: bevyengine/bevy#7594 [7605]: bevyengine/bevy#7605 [7639]: bevyengine/bevy#7639 [7642]: bevyengine/bevy#7642 [7653]: bevyengine/bevy#7653 [7701]: bevyengine/bevy#7701 [7737]: bevyengine/bevy#7737 [7756]: bevyengine/bevy#7756 Co-authored-by: François <mockersf@gmail.com> Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: Mike <mike.hsu@gmail.com> Co-authored-by: Boxy <supbscripter@gmail.com> Co-authored-by: IceSentry <c.giguere42@gmail.com> Co-authored-by: JoJoJet <21144246+JoJoJet@users.noreply.github.com> Co-authored-by: Aevyrie <aevyrie@gmail.com> Co-authored-by: James Liu <contact@jamessliu.com> Co-authored-by: Marco Buono <thecoreh@gmail.com> Co-authored-by: Aceeri <conmcclusk@gmail.com>

`ChangeTrackers<>` is a `WorldQuery` type that lets you access the change ticks for a component. bevyengine#7097 has added `Ref<>`, which gives access to a component's value in addition to its change ticks. Since bevy's access model does not separate a component's value from its change ticks, there is no benefit to using `ChangeTrackers<T>` over `Ref<T>`. Deprecate `ChangeTrackers<>`. --- * `ChangeTrackers<T>` has been deprecated. It will be removed in Bevy 0.11. `ChangeTrackers<T>` has been deprecated, and will be removed in the next release. Any usage should be replaced with `Ref<T>`. ```rust // Before (0.9) fn my_system(q: Query<(&MyComponent, ChangeTrackers<MyComponent>)>) { for (value, trackers) in &q { if trackers.is_changed() { // Do something with `value`. } } } // After (0.10) fn my_system(q: Query<Ref<MyComponent>>) { for value in &q { if value.is_changed() { // Do something with `value`. } } } ```

JoJoJet reviewed Jan 5, 2023

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alice-i-cecile added A-ECS Entities, components, systems, and events C-Usability A simple quality-of-life change that makes Bevy easier to use labels Jan 5, 2023

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Guvante force-pushed the issue-7066 branch from db59dd6 to 0a767bd Compare January 6, 2023 01:43

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alice-i-cecile added the S-Ready-For-Final-Review This PR has been approved by the community. It's ready for a maintainer to consider merging it label Jan 7, 2023

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Guvante force-pushed the issue-7066 branch from 455f593 to 70c8dee Compare January 9, 2023 01:48

Guvante added 5 commits January 10, 2023 23:23

Added Ref to allow immutable access with change detection

c0678db

- Moved Res to near ResMut in file structure - Ref formated similar to Res - Split DetectChanges to make DetectChangesMut - Created Ticks and renamed TicksMut - Standardized usage of DetectChanges and Ticks in Res/Ref

Rebased and fixed upstream changes

d44ee8a

rustfmt + moving SAFETY into block to make it more readable (safety c…

9ed1592

…omment after = makes no sense to me)

s/DetectChanges/DetectChangesMut/ and doing the SAFETY comment the 'r…

a480719

…ight' way

Made DetectChanges unconditionally imported due to it having is_chang…

e3d15f4

…ed now

Guvante force-pushed the issue-7066 branch from a1a4b07 to e3d15f4 Compare January 11, 2023 07:27

bors bot changed the title ~~Added Ref to allow immutable access with change detection~~ [Merged by Bors] - Added Ref to allow immutable access with change detection Jan 11, 2023

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Guvante deleted the issue-7066 branch January 11, 2023 16:34

james7132 mentioned this pull request Jan 12, 2023

[Merged by Bors] - Use Ref instead of &T and Changed<T> #7175

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bors bot pushed a commit that referenced this pull request Jan 12, 2023

Use Ref instead of &T and Changed<T> (#7175)

b47c466

# Objective Follow up #7097. Use `Ref<T>` instead of `&T` and the change detection query params. ## Solution Replace them.

rparrett mentioned this pull request Jan 18, 2023

Fix transform propagation of orphaned entities #7264

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JoJoJet mentioned this pull request Jan 20, 2023

[Merged by Bors] - Deprecate ChangeTrackers<T> in favor of Ref<T> #7306

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alradish pushed a commit to alradish/bevy that referenced this pull request Jan 22, 2023

Use Ref instead of &T and Changed<T> (bevyengine#7175)

e540eff

# Objective Follow up bevyengine#7097. Use `Ref<T>` instead of `&T` and the change detection query params. ## Solution Replace them.

JoJoJet mentioned this pull request Jan 28, 2023

[Merged by Bors] - Add Ref to the prelude #7392

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bors bot pushed a commit that referenced this pull request Jan 28, 2023

Add Ref to the prelude (#7392)

299bd37

# Objective Add the change-detection wrapper type `Ref<T>` (originally added in #7097) to `bevy_ecs::prelude`.

ItsDoot pushed a commit to ItsDoot/bevy that referenced this pull request Feb 1, 2023

Use Ref instead of &T and Changed<T> (bevyengine#7175)

0a3b635

# Objective Follow up bevyengine#7097. Use `Ref<T>` instead of `&T` and the change detection query params. ## Solution Replace them.

ItsDoot pushed a commit to ItsDoot/bevy that referenced this pull request Feb 1, 2023

Add Ref to the prelude (bevyengine#7392)

3c1ad47

# Objective Add the change-detection wrapper type `Ref<T>` (originally added in bevyengine#7097) to `bevy_ecs::prelude`.

cart mentioned this pull request Feb 24, 2023

[Merged by Bors] - News: Release 0.10.0 bevyengine/bevy-website#546

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[Merged by Bors] - Added Ref to allow immutable access with change detection #7097

[Merged by Bors] - Added Ref to allow immutable access with change detection #7097

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[Merged by Bors] - Added Ref to allow immutable access with change detection #7097

[Merged by Bors] - Added Ref to allow immutable access with change detection #7097

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