# Objective
- Make the many foxes not unnecessarily bright. Broken since #5666.
- Fixes#6528
## Solution
- In #5666 normalisation of normals was moved from the fragment stage to the vertex stage. However, it was not added to the vertex stage for skinned normals. The many foxes are skinned and their skinned normals were not unit normals. which made them brighter. Normalising the skinned normals fixes this.
---
## Changelog
- Fixed: Non-unit length skinned normals are now normalized.
This reverts commit 8429b6d6ca as discussed in #6522.
I tested that the game_menu example works as it should.
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
Attempting to build `bevy_tasks` produces the following error:
```
error[E0599]: no method named `is_finished` found for struct `async_executor::Task` in the current scope
--> /[...]]/bevy/crates/bevy_tasks/src/task.rs:51:16
|
51 | self.0.is_finished()
| ^^^^^^^^^^^ method not found in `async_executor::Task<T>`
```
It looks like this was introduced along with `Task::is_finished`, which delegates to `async_task::Task::is_finished`. However, the latter was only introduced in `async-task` 4.2.0; `bevy_tasks` does not explicitly depend on `async-task` but on `async-executor` ^1.3.0, which in turn depends on `async-task` ^4.0.0.
## Solution
Add an explicit dependency on `async-task` ^4.2.0.
# Objective
Copy `send_event` and friends from `World` to `WorldCell`.
Clean up `bevy_winit` using `WorldCell::send_event`.
## Changelog
Added `send_event`, `send_event_default`, and `send_event_batch` to `WorldCell`.
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
- it would be useful to inspect these structs using reflection
## Solution
- derive and register reflect
- Note that `#[reflect(Component)]` requires `Default` (or `FromWorld`) until #6060, so I implemented `Default` for `Tonemapping` with `is_enabled: false`
# Objective
The `load_internal_asset` macro is helpful when creating rendering plugins, but it doesn't support load binary assets (like those compiled as spir-v).
## Solution
Add a `load_internal_binary_asset` macro that use `include_bytes!`.
# Objective
Fixes#5393
## Solution
- Add padding to `GlobalsUniform` / `Globals` to make it 16-byte aligned.
Still not super clear on whether this is a `naga` thing or an `encase` thing or what. But now that we're offering `globals` up to users and #5393 is not just breaking an example, maybe we should do this sort of workaround?
* Move the despawn debug log from `World::despawn` to `EntityMut::despawn`.
* Move the despawn non-existent warning log from `Commands::despawn` to `World::despawn`.
This should make logging consistent regardless of which of the three `despawn` methods is used.
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
Using `Reflect` we can easily switch between a specific reflection trait object, such as a `dyn Struct`, to a `dyn Reflect` object via `Reflect::as_reflect` or `Reflect::as_reflect_mut`.
```rust
fn do_something(value: &dyn Reflect) {/* ... */}
let foo: Box<dyn Struct> = Box::new(Foo::default());
do_something(foo.as_reflect());
```
However, there is no way to convert a _boxed_ reflection trait object to a `Box<dyn Reflect>`.
## Solution
Add a `Reflect::into_reflect` method which allows converting a boxed reflection trait object back into a boxed `Reflect` trait object.
```rust
fn do_something(value: Box<dyn Reflect>) {/* ... */}
let foo: Box<dyn Struct> = Box::new(Foo::default());
do_something(foo.into_reflect());
```
---
## Changelog
- Added `Reflect::into_reflect`
# Objective
Some render plugins, like [bevy-hikari](https://github.com/cryscan/bevy-hikari) require to set `CameraRenderGraph`. In order to switch between render graphs I need to insert a new `CameraRenderGraph` component. It's not very ergonomic.
## Solution
Add `CameraRenderGraph::set` like in [Name](https://docs.rs/bevy/latest/bevy/core/struct.Name.html).
---
## Changelog
### Added
- `CameraRenderGraph::set`.
# Objective
There is no way to gen an owned value of `Reflect`.
## Solution
Add it! This was originally a part of #6421, but @MrGVSV asked me to create a separate for it to implement reflect diffing.
---
## Changelog
### Added
- `Reflect::reflect_owned` to get an owned version of `Reflect`.
# Objective
`NodeBundle` contains an `image` field, which can be misleading, because if you do supply an image there, nothing will be shown to screen. You need to use an `ImageBundle` instead.
## Solution
* `image` (`UiImage`) field is removed from `NodeBundle`,
* extraction stage queries now make an optional query for `UiImage`, if one is not found, use the image handle that is used as a default by `UiImage`: c019a60b39/crates/bevy_ui/src/ui_node.rs (L464)
* touching up docs for `NodeBundle` to help guide what `NodeBundle` should be used for
* renamed `entity.rs` to `node_bundle.rs` as that gives more of a hint regarding the module's purpose
* separating `camera_config` stuff from the pre-made UI node bundles so that `node_bundle.rs` makes more sense as a module name.
# Objective
- adding a new `.register` should not overwrite old type data
- separate crates should both be able to register the same type
I ran into this while debugging why `register::<Handle<T>>` removed the `ReflectHandle` type data from a prior `register_asset_reflect`.
## Solution
- make `register` do nothing if called again for the same type
- I also removed some unnecessary duplicate registrations
# Objective
- Fix an awkwardly phrased/typoed error message
- Actually tell users which file caused the error
- IMO we don't need to panic
## Solution
- Add a warning including the involved asset path when a non-image is found by `load_folder`
- Note: uses `let else` which is stable now
```
2022-11-03T14:17:59.006861Z WARN texture_atlas: Some(AssetPath { path: "textures/rpg/tiles/whatisthisdoinghere.ogg", label: None }) did not resolve to an `Image` asset.
```
# Objective
When an error causes `debug_checked_unreachable` to be called, the panic message unhelpfully points to the function definition instead of the place that caused the error.
## Solution
Add the `#[track_caller]` attribute in debug mode.
# Objective
Fixes: https://github.com/bevyengine/bevy/issues/6466
Summary: The UI Scaling example dynamically scales the UI which will dynamically allocate fonts to the font atlas surpassing the protective limit, throwing a panic.
## Solution
- Set TextSettings.allow_dynamic_font_size = true for the UI Scaling example. This is the ideal solution since the dynamic changes to the UI are not continuous yet still discrete.
- Update the panic text to reflect ui scaling as a potential cause
# Objective
#6461 introduced `lto = true` as a profile setting for release builds. This is causing the `run-examples` CI task to timeout.
## Solution
Remove it.
# Objective
Bevy UI (and third party plugins) currently have no good way to position themselves after all post processing effects. They currently use the tonemapping node, but this is not adequate if there is anything after tonemapping (such as FXAA).
## Solution
Add a logical `END_MAIN_PASS_POST_PROCESSING` RenderGraph node that main pass post processing effects position themselves before, and things like UIs can position themselves after.
# Objective
This PR fixes#5789, by enabling movable (and scalable) directional light shadow volumes.
## Solution
This PR changes `ExtractedDirectionalLight` to hold a copy of the `DirectionalLight` entity's `GlobalTransform`, instead of just a `direction` vector. This allows the shadow map volume (as defined by the light's `shadow_projection` field) to be transformed honoring translation _and_ scale transforms, and not just rotation.
It also augments the texel size calculation (used to determine the `shadow_normal_bias`) so that it now takes into account the upper bound of the x/y/z scale of the `GlobalTransform`.
This change makes the directional light extraction code more consistent with point and spot lights (that already use `transform`), and allows easily moving and scaling the shadow volume along with a player entity based on camera distance/angle, immediately enabling more real world use cases until we have a more sophisticated adaptive implementation, such as the one described in #3629.
**Note:** While it was previously possible to update the projection achieving a similar effect, depending on the light direction and distance to the origin, the fact that the shadow map camera was always positioned at the origin with a hardcoded `Vec3::Y` up value meant you would get sub-optimal or inconsistent/incorrect results.
---
## Changelog
### Changed
- `DirectionalLight` shadow volumes now honor translation and scale transforms
## Migration Guide
- If your directional lights were positioned at the origin and not scaled (the default, most common scenario) no changes are needed on your part; it just works as before;
- If you previously had a system for dynamically updating directional light shadow projections, you might now be able to simplify your code by updating the directional light entity's transform instead;
- In the unlikely scenario that a scene with directional lights that previously rendered shadows correctly has missing shadows, make sure your directional lights are positioned at (0, 0, 0) and are not scaled to a size that's too large or too small.
Co-authored-by: JMS55 <47158642+JMS55@users.noreply.github.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
Co-authored-by: DGriffin91 <github@dgdigital.net>
`EntityMut::remove_children` does not call `self.update_location()` which is unsound.
Verified by adding the following assertion, which fails when running the tests.
```rust
let before = self.location();
self.update_location();
assert_eq!(before, self.location());
```
I also removed incorrect messages like "parent entity is not modified" and the unhelpful "Inserting a bundle in the children entities may change the parent entity's location if they were of the same archetype" which might lead people to think that's the *only* thing that can change the entity's location.
# Changelog
Added `EntityMut::world_scope`.
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
The bloom example has a 2d camera for the UI. This is an artifact of an older version of bevy. All cameras can render the UI now.
## Solution
Remove the 2d camera
Allow passing `Vec`s of glam vector types as vertex attributes.
Alternative to #4548 and #2719
Also used some macros to cut down on all the repetition.
# Migration Guide
Implementations of `From<Vec<[u16; 4]>>` and `From<Vec<[u8; 4]>>` for `VertexAttributeValues` have been removed.
I you're passing either `Vec<[u16; 4]>` or `Vec<[u8; 4]>` into `Mesh::insert_attribute` it will now require wrapping it with right the `VertexAttributeValues` enum variant.
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
Closes#5934
Currently it is not possible to de/serialize data to non-self-describing formats using reflection.
## Solution
Add support for non-self-describing de/serialization using reflection.
This allows us to use binary formatters, like [`postcard`](https://crates.io/crates/postcard):
```rust
#[derive(Reflect, FromReflect, Debug, PartialEq)]
struct Foo {
data: String
}
let mut registry = TypeRegistry::new();
registry.register::<Foo>();
let input = Foo {
data: "Hello world!".to_string()
};
// === Serialize! === //
let serializer = ReflectSerializer::new(&input, ®istry);
let bytes: Vec<u8> = postcard::to_allocvec(&serializer).unwrap();
println!("{:?}", bytes); // Output: [129, 217, 61, 98, ...]
// === Deserialize! === //
let deserializer = UntypedReflectDeserializer::new(®istry);
let dynamic_output = deserializer
.deserialize(&mut postcard::Deserializer::from_bytes(&bytes))
.unwrap();
let output = <Foo as FromReflect>::from_reflect(dynamic_output.as_ref()).unwrap();
assert_eq!(expected, output); // OK!
```
#### Crates Tested
- ~~[`rmp-serde`](https://crates.io/crates/rmp-serde)~~ Apparently, this _is_ self-describing
- ~~[`bincode` v2.0.0-rc.1](https://crates.io/crates/bincode/2.0.0-rc.1) (using [this PR](https://github.com/bincode-org/bincode/pull/586))~~ This actually works for the latest release (v1.3.3) of [`bincode`](https://crates.io/crates/bincode) as well. You just need to be sure to use fixed-int encoding.
- [`postcard`](https://crates.io/crates/postcard)
## Future Work
Ideally, we would refactor the `serde` module, but I don't think I'll do that in this PR so as to keep the diff relatively small (and to avoid any painful rebases). This should probably be done once this is merged, though.
Some areas we could improve with a refactor:
* Split deserialization logic across multiple files
* Consolidate helper functions/structs
* Make the logic more DRY
---
## Changelog
- Add support for non-self-describing de/serialization using reflection.
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
# Objective
- Adds a bloom pass for HDR-enabled Camera3ds.
- Supersedes (and all credit due to!) https://github.com/bevyengine/bevy/pull/3430 and https://github.com/bevyengine/bevy/pull/2876
## Solution
- A threshold is applied to isolate emissive samples, and then a series of downscale and upscaling passes are applied and composited together.
- Bloom is applied to 2d or 3d Cameras with hdr: true and a BloomSettings component.
---
## Changelog
- Added a `core_pipeline::bloom::BloomSettings` component.
- Added `BloomNode` that runs between the main pass and tonemapping.
- Added a `BloomPlugin` that is loaded as part of CorePipelinePlugin.
- Added a bloom example project.
Co-authored-by: JMS55 <47158642+JMS55@users.noreply.github.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
Co-authored-by: DGriffin91 <github@dgdigital.net>
# Objective
Alternative to #6424Fixes#6226
Fixes spawning empty bundles
## Solution
Add `BundleComponentStatus` trait and implement it for `AddBundle` and a new `SpawnBundleStatus` type (which always returns an Added status). `write_components` is now generic on `BundleComponentStatus` instead of taking `AddBundle` directly. This means BundleSpawner can now avoid needing AddBundle from the Empty archetype, which means BundleSpawner no longer needs a reference to the original archetype.
In theory this cuts down on the work done in `write_components` when spawning, but I'm seeing no change in the spawn benchmarks.
# Objective
The UI pass in HDR breaks currently because the color attachment format does not match the HDR ViewTarget.
## Solution
Specialize the UI pipeline on "hdr-ness" and select the appropriate format (like we do in the other built in pipelines).
# Objective
- Fixes#4019
- Fix lighting of double-sided materials when using a negative scale
- The FlightHelmet.gltf model's hose uses a double-sided material. Loading the model with a uniform scale of -1.0, and comparing against Blender, it was identified that negating the world-space tangent, bitangent, and interpolated normal produces incorrect lighting. Discussion with Morten Mikkelsen clarified that this is both incorrect and unnecessary.
## Solution
- Remove the code that negates the T, B, and N vectors (the interpolated world-space tangent, calculated world-space bitangent, and interpolated world-space normal) when seeing the back face of a double-sided material with negative scale.
- Negate the world normal for a double-sided back face only when not using normal mapping
### Before, on `main`, flipping T, B, and N
<img width="932" alt="Screenshot 2022-08-22 at 15 11 53" src="https://user-images.githubusercontent.com/302146/185965366-f776ff2c-cfa1-46d1-9c84-fdcb399c273c.png">
### After, on this PR
<img width="932" alt="Screenshot 2022-08-22 at 15 12 11" src="https://user-images.githubusercontent.com/302146/185965420-8be493e2-3b1a-4188-bd13-fd6b17a76fe7.png">
### Double-sided material without normal maps
https://user-images.githubusercontent.com/302146/185988113-44a384e7-0b55-4946-9b99-20f8c803ab7e.mp4
---
## Changelog
- Fixed: Lighting of normal-mapped, double-sided materials applied to models with negative scale
- Fixed: Lighting and shadowing of back faces with no normal-mapping and a double-sided material
## Migration Guide
`prepare_normal` from the `bevy_pbr::pbr_functions` shader import has been reworked.
Before:
```rust
pbr_input.world_normal = in.world_normal;
pbr_input.N = prepare_normal(
pbr_input.material.flags,
in.world_normal,
#ifdef VERTEX_TANGENTS
#ifdef STANDARDMATERIAL_NORMAL_MAP
in.world_tangent,
#endif
#endif
in.uv,
in.is_front,
);
```
After:
```rust
pbr_input.world_normal = prepare_world_normal(
in.world_normal,
(material.flags & STANDARD_MATERIAL_FLAGS_DOUBLE_SIDED_BIT) != 0u,
in.is_front,
);
pbr_input.N = apply_normal_mapping(
pbr_input.material.flags,
pbr_input.world_normal,
#ifdef VERTEX_TANGENTS
#ifdef STANDARDMATERIAL_NORMAL_MAP
in.world_tangent,
#endif
#endif
in.uv,
);
```
# Objective
Replace `WorldQueryGats` trait with actual gats
## Solution
Replace `WorldQueryGats` trait with actual gats
---
## Changelog
- Replaced `WorldQueryGats` trait with actual gats
## Migration Guide
- Replace usage of `WorldQueryGats` assoc types with the actual gats on `WorldQuery` trait
Respect mipmap_filter when create ImageDescriptor with linear()/nearest()
# Objective
Fixes#6348
## Migration Guide
This PR changes default `ImageSettings` and may lead to unexpected behaviour for existing projects with mipmapped textures. Users should provide custom `ImageSettings` resource with `mipmap_filter=FilterMode::Nearest` if they want to keep old behaviour.
Co-authored-by: Yakov Borevich <j.borevich@gmail.com>
# Objective
Currently we are limiting the amount of direction lights in a scene to one.
## Solution
Increase the amount of direction lights from 1 to 10.
This still is not a perfect solution, but should unblock many use cases.
We could probably just store the directional lights similar to the point lights in an storage buffer, allowing for an variable amount of directional lights.
Co-authored-by: Kurt Kühnert <51823519+Ku95@users.noreply.github.com>
# Objective
Right now, the `TaskPool` implementation allows panics to permanently kill worker threads upon panicking. This is currently non-recoverable without using a `std::panic::catch_unwind` in every scheduled task. This is poor ergonomics and even poorer developer experience. This is exacerbated by #2250 as these threads are global and cannot be replaced after initialization.
Removes the need for temporary fixes like #4998. Fixes#4996. Fixes#6081. Fixes#5285. Fixes#5054. Supersedes #2307.
## Solution
The current solution is to wrap `Executor::run` in `TaskPool` with a `catch_unwind`, and discarding the potential panic. This was taken straight from [smol](404c7bcc0a/src/spawn.rs (L44))'s current implementation. ~~However, this is not entirely ideal as:~~
- ~~the signaled to the awaiting task. We would need to change `Task<T>` to use `async_task::FallibleTask` internally, and even then it doesn't signal *why* it panicked, just that it did.~~ (See below).
- ~~no error is logged of any kind~~ (See below)
- ~~it's unclear if it drops other tasks in the executor~~ (it does not)
- ~~This allows the ECS parallel executor to keep chugging even though a system's task has been dropped. This inevitably leads to deadlock in the executor.~~ Assuming we don't catch the unwind in ParallelExecutor, this will naturally kill the main thread.
### Alternatives
A final solution likely will incorporate elements of any or all of the following.
#### ~~Log and Ignore~~
~~Log the panic, drop the task, keep chugging. This only addresses the discoverability of the panic. The process will continue to run, probably deadlocking the executor. tokio's detatched tasks operate in this fashion.~~
Panics already do this by default, even when caught by `catch_unwind`.
#### ~~`catch_unwind` in `ParallelExecutor`~~
~~Add another layer catching system-level panics into the `ParallelExecutor`. How the executor continues when a core dependency of many systems fails to run is up for debate.~~
`async_task::Task` bubbles up panics already, this will transitively push panics all the way to the main thread.
#### ~~Emulate/Copy `tokio::JoinHandle` with `Task<T>`~~
~~`tokio::JoinHandle<T>` bubbles up the panic from the underlying task when awaited. This can be transitively applied across other APIs that also use `Task<T>` like `Query::par_for_each` and `TaskPool::scope`, bubbling up the panic until it's either caught or it reaches the main thread.~~
`async_task::Task` bubbles up panics already, this will transitively push panics all the way to the main thread.
#### Abort on Panic
The nuclear option. Log the error, abort the entire process on any thread in the task pool panicking. Definitely avoids any additional infrastructure for passing the panic around, and might actually lead to more efficient code as any unwinding is optimized out. However gives the developer zero options for dealing with the issue, a seemingly poor choice for debuggability, and prevents graceful shutdown of the process. Potentially an option for handling very low-level task management (a la #4740). Roughly takes the shape of:
```rust
struct AbortOnPanic;
impl Drop for AbortOnPanic {
fn drop(&mut self) {
abort!();
}
}
let guard = AbortOnPanic;
// Run task
std::mem::forget(AbortOnPanic);
```
---
## Changelog
Changed: `bevy_tasks::TaskPool`'s threads will no longer terminate permanently when a task scheduled onto them panics.
Changed: `bevy_tasks::Task` and`bevy_tasks::Scope` will propagate panics in the spawned tasks/scopes to the parent thread.
# Objective
Add consistent UI rendering and interaction where deep nodes inside two different hierarchies will never render on top of one-another by default and offer an escape hatch (z-index) for nodes to change their depth.
## The problem with current implementation
The current implementation of UI rendering is broken in that regard, mainly because [it sets the Z value of the `Transform` component based on a "global Z" space](https://github.com/bevyengine/bevy/blob/main/crates/bevy_ui/src/update.rs#L43) shared by all nodes in the UI. This doesn't account for the fact that each node's final `GlobalTransform` value will be relative to its parent. This effectively makes the depth unpredictable when two deep trees are rendered on top of one-another.
At the moment, it's also up to each part of the UI code to sort all of the UI nodes. The solution that's offered here does the full sorting of UI node entities once and offers the result through a resource so that all systems can use it.
## Solution
### New ZIndex component
This adds a new optional `ZIndex` enum component for nodes which offers two mechanism:
- `ZIndex::Local(i32)`: Overrides the depth of the node relative to its siblings.
- `ZIndex::Global(i32)`: Overrides the depth of the node relative to the UI root. This basically allows any node in the tree to "escape" the parent and be ordered relative to the entire UI.
Note that in the current implementation, omitting `ZIndex` on a node has the same result as adding `ZIndex::Local(0)`. Additionally, the "global" stacking context is essentially a way to add your node to the root stacking context, so using `ZIndex::Local(n)` on a root node (one without parent) will share that space with all nodes using `Index::Global(n)`.
### New UiStack resource
This adds a new `UiStack` resource which is calculated from both hierarchy and `ZIndex` during UI update and contains a vector of all node entities in the UI, ordered by depth (from farthest from camera to closest). This is exposed publicly by the bevy_ui crate with the hope that it can be used for consistent ordering and to reduce the amount of sorting that needs to be done by UI systems (i.e. instead of sorting everything by `global_transform.z` in every system, this array can be iterated over).
### New z_index example
This also adds a new z_index example that showcases the new `ZIndex` component. It's also a good general demo of the new UI stack system, because making this kind of UI was very broken with the old system (e.g. nodes would render on top of each other, not respecting hierarchy or insert order at all).
---
## Changelog
- Added the `ZIndex` component to bevy_ui.
- Added the `UiStack` resource to bevy_ui, and added implementation in a new `stack.rs` module.
- Removed the previous Z updating system from bevy_ui, because it was replaced with the above.
- Changed bevy_ui rendering to use UiStack instead of z ordering.
- Changed bevy_ui focus/interaction system to use UiStack instead of z ordering.
- Added a new z_index example.
## ZIndex demo
Here's a demo I wrote to test these features
https://user-images.githubusercontent.com/1060971/188329295-d7beebd6-9aee-43ab-821e-d437df5dbe8a.mp4
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
This reverts commit 53d387f340.
# Objective
Reverts #6448. This didn't have the intended effect: we're now getting bevy::prelude shown in the docs again.
Co-authored-by: Alejandro Pascual <alejandro.pascual.pozo@gmail.com>
# Objective
- Right now re-exports are completely hidden in prelude docs.
- Fixes#6433
## Solution
- We could show the re-exports without inlining their documentation.
# Objective
Fixes#6059, changing all incorrect occurrences of ``id`` in the ``entity`` module to ``index``:
* struct level documentation,
* ``id`` struct field,
* ``id`` method and its documentation.
## Solution
Renaming and verifying using CI.
Co-authored-by: Edvin Kjell <43633999+Edwox@users.noreply.github.com>
# Objective
In some scenarios it can be useful to check if a task has been finished without polling it. I added a function called `is_finished` to check if a task has been finished.
## Solution
Since `async_task` supports it out of the box, it is just a simple wrapper function.
---
# Objective
- Add post processing passes for FXAA (Fast Approximate Anti-Aliasing)
- Add example comparing MSAA and FXAA
## Solution
When the FXAA plugin is added, passes for FXAA are inserted between the main pass and the tonemapping pass. Supports using either HDR or LDR output from the main pass.
---
## Changelog
- Add a new FXAANode that runs after the main pass when the FXAA plugin is added.
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
For `derive(WorldQuery)`, there are three structs generated, `Item`, `Fetch` and `State`.
These inherit the visibility of the derived structure, thus `#![warn(missing_docs)]` would
warn about missing documentation for these structures.
- [ ] I'd like some advice on what to write here, as I personally don't really understand `Fetch` nor `State`.
