# Objective
- Crate-level prelude modules, such as `bevy_ecs::prelude`, are plagued
with inconsistency! Let's fix it!
## Solution
Format all preludes based on the following rules:
1. All preludes should have brief documentation in the format of:
> The _name_ prelude.
>
> This includes the most common types in this crate, re-exported for
your convenience.
2. All documentation should be outer, not inner. (`///` instead of
`//!`.)
3. No prelude modules should be annotated with `#[doc(hidden)]`. (Items
within them may, though I'm not sure why this was done.)
## Testing
- I manually searched for the term `mod prelude` and updated all
occurrences by hand. 🫠
---------
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
# Objective
As discussed in https://github.com/bevyengine/bevy/issues/7386, system
order ambiguities within `DefaultPlugins` are a source of bugs in the
engine and badly pollute diagnostic output for users.
We should eliminate them!
This PR is an alternative to #15027: with all external ambiguities
silenced, this should be much less prone to merge conflicts and the test
output should be much easier for authors to understand.
Note that system order ambiguities are still permitted in the
`RenderApp`: these need a bit of thought in terms of how to test them,
and will be fairly involved to fix. While these aren't *good*, they'll
generally only cause graphical bugs, not logic ones.
## Solution
All remaining system order ambiguities have been resolved.
Review this PR commit-by-commit to see how each of these problems were
fixed.
## Testing
`cargo run --example ambiguity_detection` passes with no panics or
logging!
This commit adds support for *masks* to the animation graph. A mask is a
set of animation targets (bones) that neither a node nor its descendants
are allowed to animate. Animation targets can be assigned one or more
*mask group*s, which are specific to a single graph. If a node masks out
any mask group that an animation target belongs to, animation curves for
that target will be ignored during evaluation.
The canonical use case for masks is to support characters holding
objects. Typically, character animations will contain hand animations in
the case that the character's hand is empty. (For example, running
animations may close a character's fingers into a fist.) However, when
the character is holding an object, the animation must be altered so
that the hand grips the object.
Bevy currently has no convenient way to handle this. The only workaround
that I can see is to have entirely separate animation clips for
characters' hands and bodies and keep them in sync, which is burdensome
and doesn't match artists' expectations from other engines, which all
effectively have support for masks. However, with mask group support,
this task is simple. We assign each hand to a mask group and parent all
character animations to a node. When a character grasps an object in
hand, we position the fingers as appropriate and then enable the mask
group for that hand in that node. This allows the character's animations
to run normally, while the object remains correctly attached to the
hand.
Note that even with this PR, we won't have support for running separate
animations for a character's hand and the rest of the character. This is
because we're missing additive blending: there's no way to combine the
two masked animations together properly. I intend that to be a follow-up
PR.
The major engines all have support for masks, though the workflow varies
from engine to engine:
* Unity has support for masks [essentially as implemented here], though
with layers instead of a tree. However, when using the Mecanim
("Humanoid") feature, precise control over bones is lost in favor of
predefined muscle groups.
* Unreal has a feature named [*layered blend per bone*]. This allows for
separate blend weights for different bones, effectively achieving masks.
I believe that the combination of blend nodes and masks make Bevy's
animation graph as expressible as that of Unreal, once we have support
for additive blending, though you may have to use more nodes than you
would in Unreal. Moreover, separating out the concepts of "blend weight"
and "which bones this node applies to" seems like a cleaner design than
what Unreal has.
* Godot's `AnimationTree` has the notion of [*blend filters*], which are
essentially the same as masks as implemented in this PR.
Additionally, this patch fixes a bug with weight evaluation whereby
weights weren't properly propagated down to grandchildren, because the
weight evaluation for a node only checked its parent's weight, not its
evaluated weight. I considered submitting this as a separate PR, but
given that this PR refactors that code entirely to support masks and
weights under a unified "evaluated node" concept, I simply included the
fix here.
A new example, `animation_masks`, has been added. It demonstrates how to
toggle masks on and off for specific portions of a skin.
This is part of #14395, but I'm going to defer closing that issue until
we have additive blending.
[essentially as implemented here]:
https://docs.unity3d.com/560/Documentation/Manual/class-AvatarMask.html
[*layered blend per bone*]:
https://dev.epicgames.com/documentation/en-us/unreal-engine/using-layered-animations-in-unreal-engine
[*blend filters*]:
https://docs.godotengine.org/en/stable/tutorials/animation/animation_tree.html
## Migration Guide
* The serialized format of animation graphs has changed with the
addition of animation masks. To upgrade animation graph RON files, add
`mask` and `mask_groups` fields as appropriate. (They can be safely set
to zero.)
# Objective
* Fixes https://github.com/bevyengine/bevy/issues/14889
## Solution
Exposes `bevy_animation::{animatable, graph, transition}` to the world.
## Testing
- Did you test these changes? If so, how?
- These changes do not need testing, as they do not modify/add/remove
any functionality.
- ~~Are there any parts that need more testing?~~
- ~~How can other people (reviewers) test your changes? Is there
anything specific they need to know?~~
- ~~If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?~~
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
`bevy_animation` imports a lot of items - and it uses a very
inconsistent code style to do so.
## Solution
Changes the offending `use` statements to be more consistent across the
crate.
## Testing
- Did you test these changes? If so, how?
- No testing is needed beyond lint checks, and those finished
successfully.
- ~~Are there any parts that need more testing?~~
- ~~How can other people (reviewers) test your changes? Is there
anything specific they need to know?~~
- ~~If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?~~
# Objective
Add a convenience constructor to make simple animation graphs easier to
build.
I've had some notes about attempting this since #11989 that I just
remembered after seeing #14852.
This partially addresses #14852, but I don't really know animation well
enough to write all of the documentation it's asking for.
## Solution
Add `AnimationGraph::from_clips` and use it to simplify `animated_fox`.
Do some other little bits of incidental cleanup and documentation .
## Testing
I ran `cargo run --example animated_fox`.
# Objective
fix#14742
## Solution
the issue arises because "finished" animations (where current time >=
last keyframe time) are not applied at all.
when transitioning from a finished animation to another later-indexed
anim, the transition kind-of works because the finished anim is skipped,
then the new anim is applied with a lower weight (weight / total_weight)
when transitioning from a finished animation to another earlier-indexed
anim, the transition is instant as the new anim is applied with 1.0 (as
weight == total_weight for the first applied), then the finished
animation is skipped.
to fix this we can always apply every animation based on the nearest 2
keyframes, and clamp the interpolation between them to [0,1].
pros:
- finished animations can be transitioned out of correctly
- blended animations where some curves have a last-keyframe before the
end of the animation will blend properly
- animations will actually finish on their last keyframe, rather than a
fraction of a render-frame before the end
cons:
- we have to re-apply finished animations every frame whether it's
necessary or not. i can't see a way to avoid this.
# Objective
While scrolling through the animation crate, I was confused by the docs
and code for the two methods. One does nothing for resetting an
animation, the other just resets the weights for whatever reason.
## Solution
Made the functions work accordingly to their documentation.
`start` now replays the animation.
And `play` doesn't reset the weight anymore. I have no clue why it
should. `play` is there to don't do anything to an already existing
animation.
## Testing
I tested the current 0.14 code with bevy playground in the Animated Fox
exampled and changed it such that on pressing space, either `play` or
`start` would be called. Neither changed anything.
I then inlined the function for start there and it restarted the
animation, so it should work.
---
## Migration Guide
`AnimationPlayer::start` now correspondingly to its docs restarts a
running animation.
`AnimationPlayer::play` doesn't reset the weight anymore.
# Objective
Fixes#14386
## Solution
- Added the `#[deprecate]` attribute to the `is_playing_animation`
function.
## Testing
The project successfully builds.
---
## Migration Guide
The user will just need to replace functions named
`is_playing_animation` with `animation_is_playing`.
# Objective
Some use cases might require holding onto the previous state of the
animation player for change detection.
## Solution
Added `clone` and `copy` implementation to most animation types.
Added optimized `clone_from` implementations for the specific use case
of holding a `PreviousAnimationPlayer` component.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
- Be able to edit animation inside the editor and save them once
modified. This will allow bevy to modify animation assets with code.
- Fixes#13052
## Solution
- Expose the previously const getters of the Animation curves
---
# Objective
i downloaded a random model from sketchfab
(https://sketchfab.com/3d-models/dragon-glass-fe00cb0ecaca4e4595874b70de7e116b)
to fiddle with bevy and encountered a panic when attempted to play
animations:
```
thread 'Compute Task Pool (3)' panicked at /home/username/code/bevy/crates/bevy_animation/src/lib.rs:848:58:
index out of bounds: the len is 40 but the index is 40
```
"Animation / Animated Fox"
(5caf085dac/examples/animation/animated_fox.rs)
example can be used for reproduction. to reproduce download a model from
sketchfab (link above) and load it instead of loading fox.glb, keep only
`dragon_glass.glb#Animation0` and remove `1` and `2` -> run and wait 1-2
seconds for crash to happen.
## Solution
correct keyframe indexing, i guess
# Objective
Minimize the number of dependencies low in the tree.
## Solution
* Remove the dependency on rustc-hash in bevy_ecs (not used) and
bevy_macro_utils (only used in one spot).
* Deduplicate the dependency on `sha1_smol` with the existing blake3
dependency already being used for bevy_asset.
* Remove the unused `ron` dependency on `bevy_app`
* Make the `serde` dependency for `bevy_ecs` optional. It's only used
for serializing Entity.
* Change the `wgpu` dependency to `wgpu-types`, and make it optional for
`bevy_color`.
* Remove the unused `thread-local` dependency on `bevy_render`.
* Make multiple dependencies for `bevy_tasks` optional and enabled only
when running with the `multi-threaded` feature. Preferably they'd be
disabled all the time on wasm, but I couldn't find a clean way to do
this.
---
## Changelog
TODO
## Migration Guide
TODO
# Objective
Resolves#3824. `unsafe` code should be the exception, not the norm in
Rust. It's obviously needed for various use cases as it's interfacing
with platforms and essentially running the borrow checker at runtime in
the ECS, but the touted benefits of Bevy is that we are able to heavily
leverage Rust's safety, and we should be holding ourselves accountable
to that by minimizing our unsafe footprint.
## Solution
Deny `unsafe_code` workspace wide. Add explicit exceptions for the
following crates, and forbid it in almost all of the others.
* bevy_ecs - Obvious given how much unsafe is needed to achieve
performant results
* bevy_ptr - Works with raw pointers, even more low level than bevy_ecs.
* bevy_render - due to needing to integrate with wgpu
* bevy_window - due to needing to integrate with raw_window_handle
* bevy_utils - Several unsafe utilities used by bevy_ecs. Ideally moved
into bevy_ecs instead of made publicly usable.
* bevy_reflect - Required for the unsafe type casting it's doing.
* bevy_transform - for the parallel transform propagation
* bevy_gizmos - For the SystemParam impls it has.
* bevy_assets - To support reflection. Might not be required, not 100%
sure yet.
* bevy_mikktspace - due to being a conversion from a C library. Pending
safe rewrite.
* bevy_dynamic_plugin - Inherently unsafe due to the dynamic loading
nature.
Several uses of unsafe were rewritten, as they did not need to be using
them:
* bevy_text - a case of `Option::unchecked` could be rewritten as a
normal for loop and match instead of an iterator.
* bevy_color - the Pod/Zeroable implementations were replaceable with
bytemuck's derive macros.
# Objective
Currently the built docs only shows the logo and favicon for the top
level `bevy` crate. This makes views like
https://docs.rs/bevy_ecs/latest/bevy_ecs/ look potentially unrelated to
the project at first glance.
## Solution
Reproduce the docs attributes for every crate that Bevy publishes.
Ideally this would be done with some workspace level Cargo.toml control,
but AFAICT, such support does not exist.
This is an implementation of RFC #51:
https://github.com/bevyengine/rfcs/blob/main/rfcs/51-animation-composition.md
Note that the implementation strategy is different from the one outlined
in that RFC, because two-phase animation has now landed.
# Objective
Bevy needs animation blending. The RFC for this is [RFC 51].
## Solution
This is an implementation of the RFC. Note that the implementation
strategy is different from the one outlined there, because two-phase
animation has now landed.
This is just a draft to get the conversation started. Currently we're
missing a few things:
- [x] A fully-fleshed-out mechanism for transitions
- [x] A serialization format for `AnimationGraph`s
- [x] Examples are broken, other than `animated_fox`
- [x] Documentation
---
## Changelog
### Added
* The `AnimationPlayer` has been reworked to support blending multiple
animations together through an `AnimationGraph`, and as such will no
longer function unless a `Handle<AnimationGraph>` has been added to the
entity containing the player. See [RFC 51] for more details.
* Transition functionality has moved from the `AnimationPlayer` to a new
component, `AnimationTransitions`, which works in tandem with the
`AnimationGraph`.
## Migration Guide
* `AnimationPlayer`s can no longer play animations by themselves and
need to be paired with a `Handle<AnimationGraph>`. Code that was using
`AnimationPlayer` to play animations will need to create an
`AnimationGraph` asset first, add a node for the clip (or clips) you
want to play, and then supply the index of that node to the
`AnimationPlayer`'s `play` method.
* The `AnimationPlayer::play_with_transition()` method has been removed
and replaced with the `AnimationTransitions` component. If you were
previously using `AnimationPlayer::play_with_transition()`, add all
animations that you were playing to the `AnimationGraph`, and create an
`AnimationTransitions` component to manage the blending between them.
[RFC 51]:
https://github.com/bevyengine/rfcs/blob/main/rfcs/51-animation-composition.md
---------
Co-authored-by: Rob Parrett <robparrett@gmail.com>
# Objective
Make bevy_utils less of a compilation bottleneck. Tackle #11478.
## Solution
* Move all of the directly reexported dependencies and move them to
where they're actually used.
* Remove the UUID utilities that have gone unused since `TypePath` took
over for `TypeUuid`.
* There was also a extraneous bytemuck dependency on `bevy_core` that
has not been used for a long time (since `encase` became the primary way
to prepare GPU buffers).
* Remove the `all_tuples` macro reexport from bevy_ecs since it's
accessible from `bevy_utils`.
---
## Changelog
Removed: Many of the reexports from bevy_utils (petgraph, uuid, nonmax,
smallvec, and thiserror).
Removed: bevy_core's reexports of bytemuck.
## Migration Guide
bevy_utils' reexports of petgraph, uuid, nonmax, smallvec, and thiserror
have been removed.
bevy_core' reexports of bytemuck's types has been removed.
Add them as dependencies in your own crate instead.
# Objective
Fix#12304. Remove unnecessary type registrations thanks to #4154.
## Solution
Conservatively remove type registrations. Keeping the top level
components, resources, and events, but dropping everything else that is
a type of a member of those types.
# Objective
Fixes#11298. Make the use of bevy_log vs bevy_utils::tracing more
consistent.
## Solution
Replace all uses of bevy_log's logging macros with the reexport from
bevy_utils. Remove bevy_log as a dependency where it's no longer needed
anymore.
Ideally we should just be using tracing directly, but given that all of
these crates are already using bevy_utils, this likely isn't that great
of a loss right now.
# Objective
Bevy's animation system currently does tree traversals based on `Name`
that aren't necessary. Not only do they require in unsafe code because
tree traversals are awkward with parallelism, but they are also somewhat
slow, brittle, and complex, which manifested itself as way too many
queries in #11670.
# Solution
Divide animation into two phases: animation *advancement* and animation
*evaluation*, which run after one another. *Advancement* operates on the
`AnimationPlayer` and sets the current animation time to match the game
time. *Evaluation* operates on all animation bones in the scene in
parallel and sets the transforms and/or morph weights based on the time
and the clip.
To do this, we introduce a new component, `AnimationTarget`, which the
asset loader places on every bone. It contains the ID of the entity
containing the `AnimationPlayer`, as well as a UUID that identifies
which bone in the animation the target corresponds to. In the case of
glTF, the UUID is derived from the full path name to the bone. The rule
that `AnimationTarget`s are descendants of the entity containing
`AnimationPlayer` is now just a convention, not a requirement; this
allows us to eliminate the unsafe code.
# Migration guide
* `AnimationClip` now uses UUIDs instead of hierarchical paths based on
the `Name` component to refer to bones. This has several consequences:
- A new component, `AnimationTarget`, should be placed on each bone that
you wish to animate, in order to specify its UUID and the associated
`AnimationPlayer`. The glTF loader automatically creates these
components as necessary, so most uses of glTF rigs shouldn't need to
change.
- Moving a bone around the tree, or renaming it, no longer prevents an
`AnimationPlayer` from affecting it.
- Dynamically changing the `AnimationPlayer` component will likely
require manual updating of the `AnimationTarget` components.
* Entities with `AnimationPlayer` components may now possess descendants
that also have `AnimationPlayer` components. They may not, however,
animate the same bones.
* As they aren't specific to `TypeId`s,
`bevy_reflect::utility::NoOpTypeIdHash` and
`bevy_reflect::utility::NoOpTypeIdHasher` have been renamed to
`bevy_reflect::utility::NoOpHash` and
`bevy_reflect::utility::NoOpHasher` respectively.
# Objective
- There are multiple instances of `let Some(x) = ... else { None };`
throughout the project.
- Because `Option<T>` implements
[`Try`](https://doc.rust-lang.org/stable/std/ops/trait.Try.html), it can
use the question mark `?` operator.
## Solution
- Use question mark operator instead of `let Some(x) = ... else { None
}`.
---
There was another PR that did a similar thing a few weeks ago, but I
couldn't find it.
# Objective
Currently the `missing_docs` lint is allowed-by-default and enabled at
crate level when their documentations is complete (see #3492).
This PR proposes to inverse this logic by making `missing_docs`
warn-by-default and mark crates with imcomplete docs allowed.
## Solution
Makes `missing_docs` warn at workspace level and allowed at crate level
when the docs is imcomplete.
# Objective
Allow animation of types other than translation, scale, and rotation on
`Transforms`.
## Solution
Add a base trait for all values that can be animated by the animation
system. This provides the basic operations for sampling and blending
animation values for more than just translation, rotation, and scale.
This implements part of bevyengine/rfcs#51, but is missing the
implementations for `Range<T>` and `Color`. This also does not fully
integrate with the existing `AnimationPlayer` yet, just setting up the
trait.
---------
Co-authored-by: Kirillov Kirill <kirusfg@gmail.com>
Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: irate <JustTheCoolDude@gmail.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Alice Cecile <alice.i.cecil@gmail.com>
# Objective
- Address a `TODO` item in `bevy_animation`.
## Solution
- Replace the `cubic_spline_interpolation` macro with a function.
The function isn't marked as `#[inline(always)]` but from what I checked
with `cargo asm` it gets inlined (even in debug, unless I explicitly add
`#[inline(never)]`), so this should be identical to the macro. If needed
I can add the attribute.
Not always, but skip it if the new length is smaller.
For context, `path_cache` is a `Vec<Vec<Option<Entity>>>`.
# Objective
Previously, when setting a new length to the `path_cache`, we would:
1. Deallocate all existing `Vec<Option<Entity>>`
2. Deallocate the `path_cache`
3. Allocate a new `Vec<Vec<Option<Entity>>>`, where each item is an
empty `Vec`, and would have to be allocated when pushed to.
This is a lot of allocations!
## Solution
Use
[`Vec::resize_with`](https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.resize_with).
With this change, what occurs is:
1. We `clear` each `Vec<Option<Entity>>`, keeping the allocation, but
making the memory of each `Vec` re-usable
2. We only append new `Vec` to `path_cache` when it is too small.
* Fixes#11328
### Note on performance
I didn't benchmark it, I just ran a diff on the generated assembly (ran
with `--profile stress-test` and `--native`). I found this PR has 20
less instructions in `apply_animation` (out of 2504).
Though on a purely abstract level, I can deduce this leads to less
allocation.
More information on profiling allocations in rust:
https://nnethercote.github.io/perf-book/heap-allocations.html
## Future work
I think a [jagged vec](https://en.wikipedia.org/wiki/Jagged_array) would
be much more pertinent. Because it allocates everything in a single
contiguous buffer.
This would avoid dancing around allocations, and reduces the overhead of
one `*mut T` and two `usize` per row, also removes indirection,
improving cache efficiency. I think it would both improve code quality
and performance.
# Objective
While working on #10832, I found this code very dense and hard to
understand.
I was not confident in my fix (or the correctness of the existing code).
## Solution
Clean up, test and document the code used in the `apply_animation`
system.
I also added a pair of length-related utility methods to `Keyframes` for
easier testing. They seemed generically useful, so I made them pub.
## Changelog
- Added `VariableCurve::find_current_keyframe` method.
- Added `Keyframes::len` and `is_empty` methods.
---------
Co-authored-by: Alice Cecile <alice.i.cecil@gmail.com>
Update to `glam` 0.25, `encase` 0.7 and `hexasphere` to 10.0
## Changelog
Added the `FloatExt` trait to the `bevy_math` prelude which adds `lerp`,
`inverse_lerp` and `remap` methods to the `f32` and `f64` types.
# Objective
The documentation for `AnimationPlayer::play` mentions a non-existent
`transition_duration` argument from an old iteration of the API. It's
confusing.
## Solution
Remove the offending sentence.
# Objective
Enables warning on `clippy::undocumented_unsafe_blocks` across the
workspace rather than only in `bevy_ecs`, `bevy_transform` and
`bevy_utils`. This adds a little awkwardness in a few areas of code that
have trivial safety or explain safety for multiple unsafe blocks with
one comment however automatically prevents these comments from being
missed.
## Solution
This adds `undocumented_unsafe_blocks = "warn"` to the workspace
`Cargo.toml` and fixes / adds a few missed safety comments. I also added
`#[allow(clippy::undocumented_unsafe_blocks)]` where the safety is
explained somewhere above.
There are a couple of safety comments I added I'm not 100% sure about in
`bevy_animation` and `bevy_render/src/view` and I'm not sure about the
use of `#[allow(clippy::undocumented_unsafe_blocks)]` compared to adding
comments like `// SAFETY: See above`.
# Objective
- Fix adding `#![allow(clippy::type_complexity)]` everywhere. like #9796
## Solution
- Use the new [lints] table that will land in 1.74
(https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#lints)
- inherit lint to the workspace, crates and examples.
```
[lints]
workspace = true
```
## Changelog
- Bump rust version to 1.74
- Enable lints table for the workspace
```toml
[workspace.lints.clippy]
type_complexity = "allow"
```
- Allow type complexity for all crates and examples
```toml
[lints]
workspace = true
```
---------
Co-authored-by: Martín Maita <47983254+mnmaita@users.noreply.github.com>
# Objective
After #9002, it seems that "single shot" animations were broken. When
completing, they would reset to their initial value. Which is generally
not what you want.
- Fixes#10480
## Solution
Avoid `%`-ing the animation after the number of completions exceeds the
specified one. Instead, we early-return. This is also true when the
player is playing in reverse.
---
## Changelog
- Avoid resetting animations after `Repeat::Never` animation completion.
# Objective
`Has<T>` was added to bevy_ecs, but we're still using the
`Option<With<T>>` pattern in multiple locations.
## Solution
Replace them with `Has<T>`.
# Objective
Fixes: #9898
## Solution
Make morph behave like other keyframes, lerping first between start and
end, and then between the current state and the result.
## Changelog
Fixed jerky morph targets
---------
Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>
Co-authored-by: CGMossa <cgmossa@gmail.com>
# Bevy Asset V2 Proposal
## Why Does Bevy Need A New Asset System?
Asset pipelines are a central part of the gamedev process. Bevy's
current asset system is missing a number of features that make it
non-viable for many classes of gamedev. After plenty of discussions and
[a long community feedback
period](https://github.com/bevyengine/bevy/discussions/3972), we've
identified a number missing features:
* **Asset Preprocessing**: it should be possible to "preprocess" /
"compile" / "crunch" assets at "development time" rather than when the
game starts up. This enables offloading expensive work from deployed
apps, faster asset loading, less runtime memory usage, etc.
* **Per-Asset Loader Settings**: Individual assets cannot define their
own loaders that override the defaults. Additionally, they cannot
provide per-asset settings to their loaders. This is a huge limitation,
as many asset types don't provide all information necessary for Bevy
_inside_ the asset. For example, a raw PNG image says nothing about how
it should be sampled (ex: linear vs nearest).
* **Asset `.meta` files**: assets should have configuration files stored
adjacent to the asset in question, which allows the user to configure
asset-type-specific settings. These settings should be accessible during
the pre-processing phase. Modifying a `.meta` file should trigger a
re-processing / re-load of the asset. It should be possible to configure
asset loaders from the meta file.
* **Processed Asset Hot Reloading**: Changes to processed assets (or
their dependencies) should result in re-processing them and re-loading
the results in live Bevy Apps.
* **Asset Dependency Tracking**: The current bevy_asset has no good way
to wait for asset dependencies to load. It punts this as an exercise for
consumers of the loader apis, which is unreasonable and error prone.
There should be easy, ergonomic ways to wait for assets to load and
block some logic on an asset's entire dependency tree loading.
* **Runtime Asset Loading**: it should be (optionally) possible to load
arbitrary assets dynamically at runtime. This necessitates being able to
deploy and run the asset server alongside Bevy Apps on _all platforms_.
For example, we should be able to invoke the shader compiler at runtime,
stream scenes from sources like the internet, etc. To keep deployed
binaries (and startup times) small, the runtime asset server
configuration should be configurable with different settings compared to
the "pre processor asset server".
* **Multiple Backends**: It should be possible to load assets from
arbitrary sources (filesystems, the internet, remote asset serves, etc).
* **Asset Packing**: It should be possible to deploy assets in
compressed "packs", which makes it easier and more efficient to
distribute assets with Bevy Apps.
* **Asset Handoff**: It should be possible to hold a "live" asset
handle, which correlates to runtime data, without actually holding the
asset in memory. Ex: it must be possible to hold a reference to a GPU
mesh generated from a "mesh asset" without keeping the mesh data in CPU
memory
* **Per-Platform Processed Assets**: Different platforms and app
distributions have different capabilities and requirements. Some
platforms need lower asset resolutions or different asset formats to
operate within the hardware constraints of the platform. It should be
possible to define per-platform asset processing profiles. And it should
be possible to deploy only the assets required for a given platform.
These features have architectural implications that are significant
enough to require a full rewrite. The current Bevy Asset implementation
got us this far, but it can take us no farther. This PR defines a brand
new asset system that implements most of these features, while laying
the foundations for the remaining features to be built.
## Bevy Asset V2
Here is a quick overview of the features introduced in this PR.
* **Asset Preprocessing**: Preprocess assets at development time into
more efficient (and configurable) representations
* **Dependency Aware**: Dependencies required to process an asset are
tracked. If an asset's processed dependency changes, it will be
reprocessed
* **Hot Reprocessing/Reloading**: detect changes to asset source files,
reprocess them if they have changed, and then hot-reload them in Bevy
Apps.
* **Only Process Changes**: Assets are only re-processed when their
source file (or meta file) has changed. This uses hashing and timestamps
to avoid processing assets that haven't changed.
* **Transactional and Reliable**: Uses write-ahead logging (a technique
commonly used by databases) to recover from crashes / forced-exits.
Whenever possible it avoids full-reprocessing / only uncompleted
transactions will be reprocessed. When the processor is running in
parallel with a Bevy App, processor asset writes block Bevy App asset
reads. Reading metadata + asset bytes is guaranteed to be transactional
/ correctly paired.
* **Portable / Run anywhere / Database-free**: The processor does not
rely on an in-memory database (although it uses some database techniques
for reliability). This is important because pretty much all in-memory
databases have unsupported platforms or build complications.
* **Configure Processor Defaults Per File Type**: You can say "use this
processor for all files of this type".
* **Custom Processors**: The `Processor` trait is flexible and
unopinionated. It can be implemented by downstream plugins.
* **LoadAndSave Processors**: Most asset processing scenarios can be
expressed as "run AssetLoader A, save the results using AssetSaver X,
and then load the result using AssetLoader B". For example, load this
png image using `PngImageLoader`, which produces an `Image` asset and
then save it using `CompressedImageSaver` (which also produces an
`Image` asset, but in a compressed format), which takes an `Image` asset
as input. This means if you have an `AssetLoader` for an asset, you are
already half way there! It also means that you can share AssetSavers
across multiple loaders. Because `CompressedImageSaver` accepts Bevy's
generic Image asset as input, it means you can also use it with some
future `JpegImageLoader`.
* **Loader and Saver Settings**: Asset Loaders and Savers can now define
their own settings types, which are passed in as input when an asset is
loaded / saved. Each asset can define its own settings.
* **Asset `.meta` files**: configure asset loaders, their settings,
enable/disable processing, and configure processor settings
* **Runtime Asset Dependency Tracking** Runtime asset dependencies (ex:
if an asset contains a `Handle<Image>`) are tracked by the asset server.
An event is emitted when an asset and all of its dependencies have been
loaded
* **Unprocessed Asset Loading**: Assets do not require preprocessing.
They can be loaded directly. A processed asset is just a "normal" asset
with some extra metadata. Asset Loaders don't need to know or care about
whether or not an asset was processed.
* **Async Asset IO**: Asset readers/writers use async non-blocking
interfaces. Note that because Rust doesn't yet support async traits,
there is a bit of manual Boxing / Future boilerplate. This will
hopefully be removed in the near future when Rust gets async traits.
* **Pluggable Asset Readers and Writers**: Arbitrary asset source
readers/writers are supported, both by the processor and the asset
server.
* **Better Asset Handles**
* **Single Arc Tree**: Asset Handles now use a single arc tree that
represents the lifetime of the asset. This makes their implementation
simpler, more efficient, and allows us to cheaply attach metadata to
handles. Ex: the AssetPath of a handle is now directly accessible on the
handle itself!
* **Const Typed Handles**: typed handles can be constructed in a const
context. No more weird "const untyped converted to typed at runtime"
patterns!
* **Handles and Ids are Smaller / Faster To Hash / Compare**: Typed
`Handle<T>` is now much smaller in memory and `AssetId<T>` is even
smaller.
* **Weak Handle Usage Reduction**: In general Handles are now considered
to be "strong". Bevy features that previously used "weak `Handle<T>`"
have been ported to `AssetId<T>`, which makes it statically clear that
the features do not hold strong handles (while retaining strong type
information). Currently Handle::Weak still exists, but it is very
possible that we can remove that entirely.
* **Efficient / Dense Asset Ids**: Assets now have efficient dense
runtime asset ids, which means we can avoid expensive hash lookups.
Assets are stored in Vecs instead of HashMaps. There are now typed and
untyped ids, which means we no longer need to store dynamic type
information in the ID for typed handles. "AssetPathId" (which was a
nightmare from a performance and correctness standpoint) has been
entirely removed in favor of dense ids (which are retrieved for a path
on load)
* **Direct Asset Loading, with Dependency Tracking**: Assets that are
defined at runtime can still have their dependencies tracked by the
Asset Server (ex: if you create a material at runtime, you can still
wait for its textures to load). This is accomplished via the (currently
optional) "asset dependency visitor" trait. This system can also be used
to define a set of assets to load, then wait for those assets to load.
* **Async folder loading**: Folder loading also uses this system and
immediately returns a handle to the LoadedFolder asset, which means
folder loading no longer blocks on directory traversals.
* **Improved Loader Interface**: Loaders now have a specific "top level
asset type", which makes returning the top-level asset simpler and
statically typed.
* **Basic Image Settings and Processing**: Image assets can now be
processed into the gpu-friendly Basic Universal format. The ImageLoader
now has a setting to define what format the image should be loaded as.
Note that this is just a minimal MVP ... plenty of additional work to do
here. To demo this, enable the `basis-universal` feature and turn on
asset processing.
* **Simpler Audio Play / AudioSink API**: Asset handle providers are
cloneable, which means the Audio resource can mint its own handles. This
means you can now do `let sink_handle = audio.play(music)` instead of
`let sink_handle = audio_sinks.get_handle(audio.play(music))`. Note that
this might still be replaced by
https://github.com/bevyengine/bevy/pull/8424.
**Removed Handle Casting From Engine Features**: Ex: FontAtlases no
longer use casting between handle types
## Using The New Asset System
### Normal Unprocessed Asset Loading
By default the `AssetPlugin` does not use processing. It behaves pretty
much the same way as the old system.
If you are defining a custom asset, first derive `Asset`:
```rust
#[derive(Asset)]
struct Thing {
value: String,
}
```
Initialize the asset:
```rust
app.init_asset:<Thing>()
```
Implement a new `AssetLoader` for it:
```rust
#[derive(Default)]
struct ThingLoader;
#[derive(Serialize, Deserialize, Default)]
pub struct ThingSettings {
some_setting: bool,
}
impl AssetLoader for ThingLoader {
type Asset = Thing;
type Settings = ThingSettings;
fn load<'a>(
&'a self,
reader: &'a mut Reader,
settings: &'a ThingSettings,
load_context: &'a mut LoadContext,
) -> BoxedFuture<'a, Result<Thing, anyhow::Error>> {
Box::pin(async move {
let mut bytes = Vec::new();
reader.read_to_end(&mut bytes).await?;
// convert bytes to value somehow
Ok(Thing {
value
})
})
}
fn extensions(&self) -> &[&str] {
&["thing"]
}
}
```
Note that this interface will get much cleaner once Rust gets support
for async traits. `Reader` is an async futures_io::AsyncRead. You can
stream bytes as they come in or read them all into a `Vec<u8>`,
depending on the context. You can use `let handle =
load_context.load(path)` to kick off a dependency load, retrieve a
handle, and register the dependency for the asset.
Then just register the loader in your Bevy app:
```rust
app.init_asset_loader::<ThingLoader>()
```
Now just add your `Thing` asset files into the `assets` folder and load
them like this:
```rust
fn system(asset_server: Res<AssetServer>) {
let handle = Handle<Thing> = asset_server.load("cool.thing");
}
```
You can check load states directly via the asset server:
```rust
if asset_server.load_state(&handle) == LoadState::Loaded { }
```
You can also listen for events:
```rust
fn system(mut events: EventReader<AssetEvent<Thing>>, handle: Res<SomeThingHandle>) {
for event in events.iter() {
if event.is_loaded_with_dependencies(&handle) {
}
}
}
```
Note the new `AssetEvent::LoadedWithDependencies`, which only fires when
the asset is loaded _and_ all dependencies (and their dependencies) have
loaded.
Unlike the old asset system, for a given asset path all `Handle<T>`
values point to the same underlying Arc. This means Handles can cheaply
hold more asset information, such as the AssetPath:
```rust
// prints the AssetPath of the handle
info!("{:?}", handle.path())
```
### Processed Assets
Asset processing can be enabled via the `AssetPlugin`. When developing
Bevy Apps with processed assets, do this:
```rust
app.add_plugins(DefaultPlugins.set(AssetPlugin::processed_dev()))
```
This runs the `AssetProcessor` in the background with hot-reloading. It
reads assets from the `assets` folder, processes them, and writes them
to the `.imported_assets` folder. Asset loads in the Bevy App will wait
for a processed version of the asset to become available. If an asset in
the `assets` folder changes, it will be reprocessed and hot-reloaded in
the Bevy App.
When deploying processed Bevy apps, do this:
```rust
app.add_plugins(DefaultPlugins.set(AssetPlugin::processed()))
```
This does not run the `AssetProcessor` in the background. It behaves
like `AssetPlugin::unprocessed()`, but reads assets from
`.imported_assets`.
When the `AssetProcessor` is running, it will populate sibling `.meta`
files for assets in the `assets` folder. Meta files for assets that do
not have a processor configured look like this:
```rust
(
meta_format_version: "1.0",
asset: Load(
loader: "bevy_render::texture::image_loader::ImageLoader",
settings: (
format: FromExtension,
),
),
)
```
This is metadata for an image asset. For example, if you have
`assets/my_sprite.png`, this could be the metadata stored at
`assets/my_sprite.png.meta`. Meta files are totally optional. If no
metadata exists, the default settings will be used.
In short, this file says "load this asset with the ImageLoader and use
the file extension to determine the image type". This type of meta file
is supported in all AssetPlugin modes. If in `Unprocessed` mode, the
asset (with the meta settings) will be loaded directly. If in
`ProcessedDev` mode, the asset file will be copied directly to the
`.imported_assets` folder. The meta will also be copied directly to the
`.imported_assets` folder, but with one addition:
```rust
(
meta_format_version: "1.0",
processed_info: Some((
hash: 12415480888597742505,
full_hash: 14344495437905856884,
process_dependencies: [],
)),
asset: Load(
loader: "bevy_render::texture::image_loader::ImageLoader",
settings: (
format: FromExtension,
),
),
)
```
`processed_info` contains `hash` (a direct hash of the asset and meta
bytes), `full_hash` (a hash of `hash` and the hashes of all
`process_dependencies`), and `process_dependencies` (the `path` and
`full_hash` of every process_dependency). A "process dependency" is an
asset dependency that is _directly_ used when processing the asset.
Images do not have process dependencies, so this is empty.
When the processor is enabled, you can use the `Process` metadata
config:
```rust
(
meta_format_version: "1.0",
asset: Process(
processor: "bevy_asset::processor::process::LoadAndSave<bevy_render::texture::image_loader::ImageLoader, bevy_render::texture::compressed_image_saver::CompressedImageSaver>",
settings: (
loader_settings: (
format: FromExtension,
),
saver_settings: (
generate_mipmaps: true,
),
),
),
)
```
This configures the asset to use the `LoadAndSave` processor, which runs
an AssetLoader and feeds the result into an AssetSaver (which saves the
given Asset and defines a loader to load it with). (for terseness
LoadAndSave will likely get a shorter/friendlier type name when [Stable
Type Paths](#7184) lands). `LoadAndSave` is likely to be the most common
processor type, but arbitrary processors are supported.
`CompressedImageSaver` saves an `Image` in the Basis Universal format
and configures the ImageLoader to load it as basis universal. The
`AssetProcessor` will read this meta, run it through the LoadAndSave
processor, and write the basis-universal version of the image to
`.imported_assets`. The final metadata will look like this:
```rust
(
meta_format_version: "1.0",
processed_info: Some((
hash: 905599590923828066,
full_hash: 9948823010183819117,
process_dependencies: [],
)),
asset: Load(
loader: "bevy_render::texture::image_loader::ImageLoader",
settings: (
format: Format(Basis),
),
),
)
```
To try basis-universal processing out in Bevy examples, (for example
`sprite.rs`), change `add_plugins(DefaultPlugins)` to
`add_plugins(DefaultPlugins.set(AssetPlugin::processed_dev()))` and run
with the `basis-universal` feature enabled: `cargo run
--features=basis-universal --example sprite`.
To create a custom processor, there are two main paths:
1. Use the `LoadAndSave` processor with an existing `AssetLoader`.
Implement the `AssetSaver` trait, register the processor using
`asset_processor.register_processor::<LoadAndSave<ImageLoader,
CompressedImageSaver>>(image_saver.into())`.
2. Implement the `Process` trait directly and register it using:
`asset_processor.register_processor(thing_processor)`.
You can configure default processors for file extensions like this:
```rust
asset_processor.set_default_processor::<ThingProcessor>("thing")
```
There is one more metadata type to be aware of:
```rust
(
meta_format_version: "1.0",
asset: Ignore,
)
```
This will ignore the asset during processing / prevent it from being
written to `.imported_assets`.
The AssetProcessor stores a transaction log at `.imported_assets/log`
and uses it to gracefully recover from unexpected stops. This means you
can force-quit the processor (and Bevy Apps running the processor in
parallel) at arbitrary times!
`.imported_assets` is "local state". It should _not_ be checked into
source control. It should also be considered "read only". In practice,
you _can_ modify processed assets and processed metadata if you really
need to test something. But those modifications will not be represented
in the hashes of the assets, so the processed state will be "out of
sync" with the source assets. The processor _will not_ fix this for you.
Either revert the change after you have tested it, or delete the
processed files so they can be re-populated.
## Open Questions
There are a number of open questions to be discussed. We should decide
if they need to be addressed in this PR and if so, how we will address
them:
### Implied Dependencies vs Dependency Enumeration
There are currently two ways to populate asset dependencies:
* **Implied via AssetLoaders**: if an AssetLoader loads an asset (and
retrieves a handle), a dependency is added to the list.
* **Explicit via the optional Asset::visit_dependencies**: if
`server.load_asset(my_asset)` is called, it will call
`my_asset.visit_dependencies`, which will grab dependencies that have
been manually defined for the asset via the Asset trait impl (which can
be derived).
This means that defining explicit dependencies is optional for "loaded
assets". And the list of dependencies is always accurate because loaders
can only produce Handles if they register dependencies. If an asset was
loaded with an AssetLoader, it only uses the implied dependencies. If an
asset was created at runtime and added with
`asset_server.load_asset(MyAsset)`, it will use
`Asset::visit_dependencies`.
However this can create a behavior mismatch between loaded assets and
equivalent "created at runtime" assets if `Assets::visit_dependencies`
doesn't exactly match the dependencies produced by the AssetLoader. This
behavior mismatch can be resolved by completely removing "implied loader
dependencies" and requiring `Asset::visit_dependencies` to supply
dependency data. But this creates two problems:
* It makes defining loaded assets harder and more error prone: Devs must
remember to manually annotate asset dependencies with `#[dependency]`
when deriving `Asset`. For more complicated assets (such as scenes), the
derive likely wouldn't be sufficient and a manual `visit_dependencies`
impl would be required.
* Removes the ability to immediately kick off dependency loads: When
AssetLoaders retrieve a Handle, they also immediately kick off an asset
load for the handle, which means it can start loading in parallel
_before_ the asset finishes loading. For large assets, this could be
significant. (although this could be mitigated for processed assets if
we store dependencies in the processed meta file and load them ahead of
time)
### Eager ProcessorDev Asset Loading
I made a controversial call in the interest of fast startup times ("time
to first pixel") for the "processor dev mode configuration". When
initializing the AssetProcessor, current processed versions of unchanged
assets are yielded immediately, even if their dependencies haven't been
checked yet for reprocessing. This means that
non-current-state-of-filesystem-but-previously-valid assets might be
returned to the App first, then hot-reloaded if/when their dependencies
change and the asset is reprocessed.
Is this behavior desirable? There is largely one alternative: do not
yield an asset from the processor to the app until all of its
dependencies have been checked for changes. In some common cases (load
dependency has not changed since last run) this will increase startup
time. The main question is "by how much" and is that slower startup time
worth it in the interest of only yielding assets that are true to the
current state of the filesystem. Should this be configurable? I'm
starting to think we should only yield an asset after its (historical)
dependencies have been checked for changes + processed as necessary, but
I'm curious what you all think.
### Paths Are Currently The Only Canonical ID / Do We Want Asset UUIDs?
In this implementation AssetPaths are the only canonical asset
identifier (just like the previous Bevy Asset system and Godot). Moving
assets will result in re-scans (and currently reprocessing, although
reprocessing can easily be avoided with some changes). Asset
renames/moves will break code and assets that rely on specific paths,
unless those paths are fixed up.
Do we want / need "stable asset uuids"? Introducing them is very
possible:
1. Generate a UUID and include it in .meta files
2. Support UUID in AssetPath
3. Generate "asset indices" which are loaded on startup and map UUIDs to
paths.
4 (maybe). Consider only supporting UUIDs for processed assets so we can
generate quick-to-load indices instead of scanning meta files.
The main "pro" is that assets referencing UUIDs don't need to be
migrated when a path changes. The main "con" is that UUIDs cannot be
"lazily resolved" like paths. They need a full view of all assets to
answer the question "does this UUID exist". Which means UUIDs require
the AssetProcessor to fully finish startup scans before saying an asset
doesnt exist. And they essentially require asset pre-processing to use
in apps, because scanning all asset metadata files at runtime to resolve
a UUID is not viable for medium-to-large apps. It really requires a
pre-generated UUID index, which must be loaded before querying for
assets.
I personally think this should be investigated in a separate PR. Paths
aren't going anywhere ... _everyone_ uses filesystems (and
filesystem-like apis) to manage their asset source files. I consider
them permanent canonical asset information. Additionally, they behave
well for both processed and unprocessed asset modes. Given that Bevy is
supporting both, this feels like the right canonical ID to start with.
UUIDS (and maybe even other indexed-identifier types) can be added later
as necessary.
### Folder / File Naming Conventions
All asset processing config currently lives in the `.imported_assets`
folder. The processor transaction log is in `.imported_assets/log`.
Processed assets are added to `.imported_assets/Default`, which will
make migrating to processed asset profiles (ex: a
`.imported_assets/Mobile` profile) a non-breaking change. It also allows
us to create top-level files like `.imported_assets/log` without it
being interpreted as an asset. Meta files currently have a `.meta`
suffix. Do we like these names and conventions?
### Should the `AssetPlugin::processed_dev` configuration enable
`watch_for_changes` automatically?
Currently it does (which I think makes sense), but it does make it the
only configuration that enables watch_for_changes by default.
### Discuss on_loaded High Level Interface:
This PR includes a very rough "proof of concept" `on_loaded` system
adapter that uses the `LoadedWithDependencies` event in combination with
`asset_server.load_asset` dependency tracking to support this pattern
```rust
fn main() {
App::new()
.init_asset::<MyAssets>()
.add_systems(Update, on_loaded(create_array_texture))
.run();
}
#[derive(Asset, Clone)]
struct MyAssets {
#[dependency]
picture_of_my_cat: Handle<Image>,
#[dependency]
picture_of_my_other_cat: Handle<Image>,
}
impl FromWorld for ArrayTexture {
fn from_world(world: &mut World) -> Self {
picture_of_my_cat: server.load("meow.png"),
picture_of_my_other_cat: server.load("meeeeeeeow.png"),
}
}
fn spawn_cat(In(my_assets): In<MyAssets>, mut commands: Commands) {
commands.spawn(SpriteBundle {
texture: my_assets.picture_of_my_cat.clone(),
..default()
});
commands.spawn(SpriteBundle {
texture: my_assets.picture_of_my_other_cat.clone(),
..default()
});
}
```
The implementation is _very_ rough. And it is currently unsafe because
`bevy_ecs` doesn't expose some internals to do this safely from inside
`bevy_asset`. There are plenty of unanswered questions like:
* "do we add a Loadable" derive? (effectively automate the FromWorld
implementation above)
* Should `MyAssets` even be an Asset? (largely implemented this way
because it elegantly builds on `server.load_asset(MyAsset { .. })`
dependency tracking).
We should think hard about what our ideal API looks like (and if this is
a pattern we want to support). Not necessarily something we need to
solve in this PR. The current `on_loaded` impl should probably be
removed from this PR before merging.
## Clarifying Questions
### What about Assets as Entities?
This Bevy Asset V2 proposal implementation initially stored Assets as
ECS Entities. Instead of `AssetId<T>` + the `Assets<T>` resource it used
`Entity` as the asset id and Asset values were just ECS components.
There are plenty of compelling reasons to do this:
1. Easier to inline assets in Bevy Scenes (as they are "just" normal
entities + components)
2. More flexible queries: use the power of the ECS to filter assets (ex:
`Query<Mesh, With<Tree>>`).
3. Extensible. Users can add arbitrary component data to assets.
4. Things like "component visualization tools" work out of the box to
visualize asset data.
However Assets as Entities has a ton of caveats right now:
* We need to be able to allocate entity ids without a direct World
reference (aka rework id allocator in Entities ... i worked around this
in my prototypes by just pre allocating big chunks of entities)
* We want asset change events in addition to ECS change tracking ... how
do we populate them when mutations can come from anywhere? Do we use
Changed queries? This would require iterating over the change data for
all assets every frame. Is this acceptable or should we implement a new
"event based" component change detection option?
* Reconciling manually created assets with asset-system managed assets
has some nuance (ex: are they "loaded" / do they also have that
component metadata?)
* "how do we handle "static" / default entity handles" (ties in to the
Entity Indices discussion:
https://github.com/bevyengine/bevy/discussions/8319). This is necessary
for things like "built in" assets and default handles in things like
SpriteBundle.
* Storing asset information as a component makes it easy to "invalidate"
asset state by removing the component (or forcing modifications).
Ideally we have ways to lock this down (some combination of Rust type
privacy and ECS validation)
In practice, how we store and identify assets is a reasonably
superficial change (porting off of Assets as Entities and implementing
dedicated storage + ids took less than a day). So once we sort out the
remaining challenges the flip should be straightforward. Additionally, I
do still have "Assets as Entities" in my commit history, so we can reuse
that work. I personally think "assets as entities" is a good endgame,
but it also doesn't provide _significant_ value at the moment and it
certainly isn't ready yet with the current state of things.
### Why not Distill?
[Distill](https://github.com/amethyst/distill) is a high quality fully
featured asset system built in Rust. It is very natural to ask "why not
just use Distill?".
It is also worth calling out that for awhile, [we planned on adopting
Distill / I signed off on
it](https://github.com/bevyengine/bevy/issues/708).
However I think Bevy has a number of constraints that make Distill
adoption suboptimal:
* **Architectural Simplicity:**
* Distill's processor requires an in-memory database (lmdb) and RPC
networked API (using Cap'n Proto). Each of these introduces API
complexity that increases maintenance burden and "code grokability".
Ignoring tests, documentation, and examples, Distill has 24,237 lines of
Rust code (including generated code for RPC + database interactions). If
you ignore generated code, it has 11,499 lines.
* Bevy builds the AssetProcessor and AssetServer using pluggable
AssetReader/AssetWriter Rust traits with simple io interfaces. They do
not necessitate databases or RPC interfaces (although Readers/Writers
could use them if that is desired). Bevy Asset V2 (at the time of
writing this PR) is 5,384 lines of Rust code (ignoring tests,
documentation, and examples). Grain of salt: Distill does have more
features currently (ex: Asset Packing, GUIDS, remote-out-of-process
asset processor). I do plan to implement these features in Bevy Asset V2
and I personally highly doubt they will meaningfully close the 6115
lines-of-code gap.
* This complexity gap (which while illustrated by lines of code, is much
bigger than just that) is noteworthy to me. Bevy should be hackable and
there are pillars of Distill that are very hard to understand and
extend. This is a matter of opinion (and Bevy Asset V2 also has
complicated areas), but I think Bevy Asset V2 is much more approachable
for the average developer.
* Necessary disclaimer: counting lines of code is an extremely rough
complexity metric. Read the code and form your own opinions.
* **Optional Asset Processing:** Not all Bevy Apps (or Bevy App
developers) need / want asset preprocessing. Processing increases the
complexity of the development environment by introducing things like
meta files, imported asset storage, running processors in the
background, waiting for processing to finish, etc. Distill _requires_
preprocessing to work. With Bevy Asset V2 processing is fully opt-in.
The AssetServer isn't directly aware of asset processors at all.
AssetLoaders only care about converting bytes to runtime Assets ... they
don't know or care if the bytes were pre-processed or not. Processing is
"elegantly" (forgive my self-congratulatory phrasing) layered on top and
builds on the existing Asset system primitives.
* **Direct Filesystem Access to Processed Asset State:** Distill stores
processed assets in a database. This makes debugging / inspecting the
processed outputs harder (either requires special tooling to query the
database or they need to be "deployed" to be inspected). Bevy Asset V2,
on the other hand, stores processed assets in the filesystem (by default
... this is configurable). This makes interacting with the processed
state more natural. Note that both Godot and Unity's new asset system
store processed assets in the filesystem.
* **Portability**: Because Distill's processor uses lmdb and RPC
networking, it cannot be run on certain platforms (ex: lmdb is a
non-rust dependency that cannot run on the web, some platforms don't
support running network servers). Bevy should be able to process assets
everywhere (ex: run the Bevy Editor on the web, compile + process
shaders on mobile, etc). Distill does partially mitigate this problem by
supporting "streaming" assets via the RPC protocol, but this is not a
full solve from my perspective. And Bevy Asset V2 can (in theory) also
stream assets (without requiring RPC, although this isn't implemented
yet)
Note that I _do_ still think Distill would be a solid asset system for
Bevy. But I think the approach in this PR is a better solve for Bevy's
specific "asset system requirements".
### Doesn't async-fs just shim requests to "sync" `std::fs`? What is the
point?
"True async file io" has limited / spotty platform support. async-fs
(and the rust async ecosystem generally ... ex Tokio) currently use
async wrappers over std::fs that offload blocking requests to separate
threads. This may feel unsatisfying, but it _does_ still provide value
because it prevents our task pools from blocking on file system
operations (which would prevent progress when there are many tasks to
do, but all threads in a pool are currently blocking on file system
ops).
Additionally, using async APIs for our AssetReaders and AssetWriters
also provides value because we can later add support for "true async
file io" for platforms that support it. _And_ we can implement other
"true async io" asset backends (such as networked asset io).
## Draft TODO
- [x] Fill in missing filesystem event APIs: file removed event (which
is expressed as dangling RenameFrom events in some cases), file/folder
renamed event
- [x] Assets without loaders are not moved to the processed folder. This
breaks things like referenced `.bin` files for GLTFs. This should be
configurable per-non-asset-type.
- [x] Initial implementation of Reflect and FromReflect for Handle. The
"deserialization" parity bar is low here as this only worked with static
UUIDs in the old impl ... this is a non-trivial problem. Either we add a
Handle::AssetPath variant that gets "upgraded" to a strong handle on
scene load or we use a separate AssetRef type for Bevy scenes (which is
converted to a runtime Handle on load). This deserves its own discussion
in a different pr.
- [x] Populate read_asset_bytes hash when run by the processor (a bit of
a special case .. when run by the processor the processed meta will
contain the hash so we don't need to compute it on the spot, but we
don't want/need to read the meta when run by the main AssetServer)
- [x] Delay hot reloading: currently filesystem events are handled
immediately, which creates timing issues in some cases. For example hot
reloading images can sometimes break because the image isn't finished
writing. We should add a delay, likely similar to the [implementation in
this PR](https://github.com/bevyengine/bevy/pull/8503).
- [x] Port old platform-specific AssetIo implementations to the new
AssetReader interface (currently missing Android and web)
- [x] Resolve on_loaded unsafety (either by removing the API entirely or
removing the unsafe)
- [x] Runtime loader setting overrides
- [x] Remove remaining unwraps that should be error-handled. There are
number of TODOs here
- [x] Pretty AssetPath Display impl
- [x] Document more APIs
- [x] Resolve spurious "reloading because it has changed" events (to
repro run load_gltf with `processed_dev()`)
- [x] load_dependency hot reloading currently only works for processed
assets. If processing is disabled, load_dependency changes are not hot
reloaded.
- [x] Replace AssetInfo dependency load/fail counters with
`loading_dependencies: HashSet<UntypedAssetId>` to prevent reloads from
(potentially) breaking counters. Storing this will also enable
"dependency reloaded" events (see [Next Steps](#next-steps))
- [x] Re-add filesystem watcher cargo feature gate (currently it is not
optional)
- [ ] Migration Guide
- [ ] Changelog
## Followup TODO
- [ ] Replace "eager unchanged processed asset loading" behavior with
"don't returned unchanged processed asset until dependencies have been
checked".
- [ ] Add true `Ignore` AssetAction that does not copy the asset to the
imported_assets folder.
- [ ] Finish "live asset unloading" (ex: free up CPU asset memory after
uploading an image to the GPU), rethink RenderAssets, and port renderer
features. The `Assets` collection uses `Option<T>` for asset storage to
support its removal. (1) the Option might not actually be necessary ...
might be able to just remove from the collection entirely (2) need to
finalize removal apis
- [ ] Try replacing the "channel based" asset id recycling with
something a bit more efficient (ex: we might be able to use raw atomic
ints with some cleverness)
- [ ] Consider adding UUIDs to processed assets (scoped just to helping
identify moved assets ... not exposed to load queries ... see [Next
Steps](#next-steps))
- [ ] Store "last modified" source asset and meta timestamps in
processed meta files to enable skipping expensive hashing when the file
wasn't changed
- [ ] Fix "slow loop" handle drop fix
- [ ] Migrate to TypeName
- [x] Handle "loader preregistration". See #9429
## Next Steps
* **Configurable per-type defaults for AssetMeta**: It should be
possible to add configuration like "all png image meta should default to
using nearest sampling" (currently this hard-coded per-loader/processor
Settings::default() impls). Also see the "Folder Meta" bullet point.
* **Avoid Reprocessing on Asset Renames / Moves**: See the "canonical
asset ids" discussion in [Open Questions](#open-questions) and the
relevant bullet point in [Draft TODO](#draft-todo). Even without
canonical ids, folder renames could avoid reprocessing in some cases.
* **Multiple Asset Sources**: Expand AssetPath to support "asset source
names" and support multiple AssetReaders in the asset server (ex:
`webserver://some_path/image.png` backed by an Http webserver
AssetReader). The "default" asset reader would use normal
`some_path/image.png` paths. Ideally this works in combination with
multiple AssetWatchers for hot-reloading
* **Stable Type Names**: this pr removes the TypeUuid requirement from
assets in favor of `std::any::type_name`. This makes defining assets
easier (no need to generate a new uuid / use weird proc macro syntax).
It also makes reading meta files easier (because things have "friendly
names"). We also use type names for components in scene files. If they
are good enough for components, they are good enough for assets. And
consistency across Bevy pillars is desirable. However,
`std::any::type_name` is not guaranteed to be stable (although in
practice it is). We've developed a [stable type
path](https://github.com/bevyengine/bevy/pull/7184) to resolve this,
which should be adopted when it is ready.
* **Command Line Interface**: It should be possible to run the asset
processor in a separate process from the command line. This will also
require building a network-server-backed AssetReader to communicate
between the app and the processor. We've been planning to build a "bevy
cli" for awhile. This seems like a good excuse to build it.
* **Asset Packing**: This is largely an additive feature, so it made
sense to me to punt this until we've laid the foundations in this PR.
* **Per-Platform Processed Assets**: It should be possible to generate
assets for multiple platforms by supporting multiple "processor
profiles" per asset (ex: compress with format X on PC and Y on iOS). I
think there should probably be arbitrary "profiles" (which can be
separate from actual platforms), which are then assigned to a given
platform when generating the final asset distribution for that platform.
Ex: maybe devs want a "Mobile" profile that is shared between iOS and
Android. Or a "LowEnd" profile shared between web and mobile.
* **Versioning and Migrations**: Assets, Loaders, Savers, and Processors
need to have versions to determine if their schema is valid. If an asset
/ loader version is incompatible with the current version expected at
runtime, the processor should be able to migrate them. I think we should
try using Bevy Reflect for this, as it would allow us to load the old
version as a dynamic Reflect type without actually having the old Rust
type. It would also allow us to define "patches" to migrate between
versions (Bevy Reflect devs are currently working on patching). The
`.meta` file already has its own format version. Migrating that to new
versions should also be possible.
* **Real Copy-on-write AssetPaths**: Rust's actual Cow (clone-on-write
type) currently used by AssetPath can still result in String clones that
aren't actually necessary (cloning an Owned Cow clones the contents).
Bevy's asset system requires cloning AssetPaths in a number of places,
which result in actual clones of the internal Strings. This is not
efficient. AssetPath internals should be reworked to exhibit truer
cow-like-behavior that reduces String clones to the absolute minimum.
* **Consider processor-less processing**: In theory the AssetServer
could run processors "inline" even if the background AssetProcessor is
disabled. If we decide this is actually desirable, we could add this.
But I don't think its a priority in the short or medium term.
* **Pre-emptive dependency loading**: We could encode dependencies in
processed meta files, which could then be used by the Asset Server to
kick of dependency loads as early as possible (prior to starting the
actual asset load). Is this desirable? How much time would this save in
practice?
* **Optimize Processor With UntypedAssetIds**: The processor exclusively
uses AssetPath to identify assets currently. It might be possible to
swap these out for UntypedAssetIds in some places, which are smaller /
cheaper to hash and compare.
* **One to Many Asset Processing**: An asset source file that produces
many assets currently must be processed into a single "processed" asset
source. If labeled assets can be written separately they can each have
their own configured savers _and_ they could be loaded more granularly.
Definitely worth exploring!
* **Automatically Track "Runtime-only" Asset Dependencies**: Right now,
tracking "created at runtime" asset dependencies requires adding them
via `asset_server.load_asset(StandardMaterial::default())`. I think with
some cleverness we could also do this for
`materials.add(StandardMaterial::default())`, making tracking work
"everywhere". There are challenges here relating to change detection /
ensuring the server is made aware of dependency changes. This could be
expensive in some cases.
* **"Dependency Changed" events**: Some assets have runtime artifacts
that need to be re-generated when one of their dependencies change (ex:
regenerate a material's bind group when a Texture needs to change). We
are generating the dependency graph so we can definitely produce these
events. Buuuuut generating these events will have a cost / they could be
high frequency for some assets, so we might want this to be opt-in for
specific cases.
* **Investigate Storing More Information In Handles**: Handles can now
store arbitrary information, which makes it cheaper and easier to
access. How much should we move into them? Canonical asset load states
(via atomics)? (`handle.is_loaded()` would be very cool). Should we
store the entire asset and remove the `Assets<T>` collection?
(`Arc<RwLock<Option<Image>>>`?)
* **Support processing and loading files without extensions**: This is a
pretty arbitrary restriction and could be supported with very minimal
changes.
* **Folder Meta**: It would be nice if we could define per folder
processor configuration defaults (likely in a `.meta` or `.folder_meta`
file). Things like "default to linear filtering for all Images in this
folder".
* **Replace async_broadcast with event-listener?** This might be
approximately drop-in for some uses and it feels more light weight
* **Support Running the AssetProcessor on the Web**: Most of the hard
work is done here, but there are some easy straggling TODOs (make the
transaction log an interface instead of a direct file writer so we can
write a web storage backend, implement an AssetReader/AssetWriter that
reads/writes to something like LocalStorage).
* **Consider identifying and preventing circular dependencies**: This is
especially important for "processor dependencies", as processing will
silently never finish in these cases.
* **Built-in/Inlined Asset Hot Reloading**: This PR regresses
"built-in/inlined" asset hot reloading (previously provided by the
DebugAssetServer). I'm intentionally punting this because I think it can
be cleanly implemented with "multiple asset sources" by registering a
"debug asset source" (ex: `debug://bevy_pbr/src/render/pbr.wgsl` asset
paths) in combination with an AssetWatcher for that asset source and
support for "manually loading pats with asset bytes instead of
AssetReaders". The old DebugAssetServer was quite nasty and I'd love to
avoid that hackery going forward.
* **Investigate ways to remove double-parsing meta files**: Parsing meta
files currently involves parsing once with "minimal" versions of the
meta file to extract the type name of the loader/processor config, then
parsing again to parse the "full" meta. This is suboptimal. We should be
able to define custom deserializers that (1) assume the loader/processor
type name comes first (2) dynamically looks up the loader/processor
registrations to deserialize settings in-line (similar to components in
the bevy scene format). Another alternative: deserialize as dynamic
Reflect objects and then convert.
* **More runtime loading configuration**: Support using the Handle type
as a hint to select an asset loader (instead of relying on AssetPath
extensions)
* **More high level Processor trait implementations**: For example, it
might be worth adding support for arbitrary chains of "asset transforms"
that modify an in-memory asset representation between loading and
saving. (ex: load a Mesh, run a `subdivide_mesh` transform, followed by
a `flip_normals` transform, then save the mesh to an efficient
compressed format).
* **Bevy Scene Handle Deserialization**: (see the relevant [Draft TODO
item](#draft-todo) for context)
* **Explore High Level Load Interfaces**: See [this
discussion](#discuss-on_loaded-high-level-interface) for one prototype.
* **Asset Streaming**: It would be great if we could stream Assets (ex:
stream a long video file piece by piece)
* **ID Exchanging**: In this PR Asset Handles/AssetIds are bigger than
they need to be because they have a Uuid enum variant. If we implement
an "id exchanging" system that trades Uuids for "efficient runtime ids",
we can cut down on the size of AssetIds, making them more efficient.
This has some open design questions, such as how to spawn entities with
"default" handle values (as these wouldn't have access to the exchange
api in the current system).
* **Asset Path Fixup Tooling**: Assets that inline asset paths inside
them will break when an asset moves. The asset system provides the
functionality to detect when paths break. We should build a framework
that enables formats to define "path migrations". This is especially
important for scene files. For editor-generated files, we should also
consider using UUIDs (see other bullet point) to avoid the need to
migrate in these cases.
---------
Co-authored-by: BeastLe9enD <beastle9end@outlook.de>
Co-authored-by: Mike <mike.hsu@gmail.com>
Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>
# Objective
I've been collecting some mistakes in the documentation and fixed them
---------
Co-authored-by: Emi <emanuel.boehm@gmail.com>
Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>
# Objective
fixes#8357
gltf animations can affect multiple "root" nodes (i.e. top level nodes
within a gltf scene).
the current loader adds an AnimationPlayer to each root node which is
affected by any animation. when a clip which affects multiple root nodes
is played on a root node player, the root node name is not checked,
leading to potentially incorrect weights being applied.
also, the `AnimationClip::compatible_with` method will never return true
for those clips, as it checks that all paths start with the root node
name - not all paths start with the same name so it can't return true.
## Solution
- check the first path node name matches the given root
- change compatible_with to return true if `any` match is found
a better alternative would probably be to attach the player to the scene
root instead of the first child, and then walk the full path from there.
this would be breaking (and would stop multiple animations that *don't*
overlap from being played concurrently), but i'm happy to modify to that
if it's preferred.
---------
Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>
# Objective
Added `AnimationPlayer` API UX improvements.
- Succestor to https://github.com/bevyengine/bevy/pull/5912
- Fixes https://github.com/bevyengine/bevy/issues/5848
_(Credits to @asafigan for filing #5848, creating the initial pull
request, and the discussion in #5912)_
## Solution
- Created `RepeatAnimation` enum to describe an animation repetition
behavior.
- Added `is_finished()`, `set_repeat()`, and `is_playback_reversed()`
methods to the animation player.
- ~~Made the animation clip optional as per the comment from #5912~~
> ~~My problem is that the default handle [used the initialize a
`PlayingAnimation`] could actually refer to an actual animation if an
AnimationClip is set for the default handle, which leads me to ask,
"Should animation_clip should be an Option?"~~
- Added an accessor for the animation clip `animation_clip()` to the
animation player.
To determine if an animation is finished, we use the number of times the
animation has completed and the repetition behavior. If the animation is
playing in reverse then `elapsed < 0.0` counts as a completion.
Otherwise, `elapsed > animation.duration` counts as a completion. This
is what I would expect, personally. If there's any ambiguity, perhaps we
could add some `AnimationCompletionBehavior`, to specify that kind of
completion behavior to use.
Update: Previously `PlayingAnimation::elapsed` was being used as the
seek time into the animation clip. This was misleading because if you
increased the speed of the animation it would also increase (or
decrease) the elapsed time. In other words, the elapsed time was not
actually the elapsed time. To solve this, we introduce
`PlayingAnimation::seek_time` to serve as the value we manipulate the
move between keyframes. Consequently, `elapsed()` now returns the actual
elapsed time, and is not effected by the animation speed. Because
`set_elapsed` was being used to manipulate the displayed keyframe, we
introduce `AnimationPlayer::seek_to` and `AnimationPlayer::replay` to
provide this functionality.
## Migration Guide
- Removed `set_elapsed`.
- Removed `stop_repeating` in favour of
`AnimationPlayer::set_repeat(RepeatAnimation::Never)`.
- Introduced `seek_to` to seek to a given timestamp inside of the
animation.
- Introduced `seek_time` accessor for the `PlayingAnimation::seek_to`.
- Introduced `AnimationPlayer::replay` to reset the `PlayingAnimation`
to a state where no time has elapsed.
---------
Co-authored-by: Hennadii Chernyshchyk <genaloner@gmail.com>
Co-authored-by: François <mockersf@gmail.com>
# Objective
[Rust 1.72.0](https://blog.rust-lang.org/2023/08/24/Rust-1.72.0.html) is
now stable.
# Notes
- `let-else` formatting has arrived!
- I chose to allow `explicit_iter_loop` due to
https://github.com/rust-lang/rust-clippy/issues/11074.
We didn't hit any of the false positives that prevent compilation, but
fixing this did produce a lot of the "symbol soup" mentioned, e.g. `for
image in &mut *image_events {`.
Happy to undo this if there's consensus the other way.
---------
Co-authored-by: François <mockersf@gmail.com>
Need this for a custom `AnimationPlayer` that I tick in `FixedUpdate`
# Objective
- Need access to an animation clip's `paths` from outside the module
## Solution
- Add a getter method to return a reference to `paths`
---------
Co-authored-by: Tristan Guichaoua <33934311+tguichaoua@users.noreply.github.com>
# Objective
The `QueryParIter::for_each_mut` function is required when doing
parallel iteration with mutable queries.
This results in an unfortunate stutter:
`query.par_iter_mut().par_for_each_mut()` ('mut' is repeated).
## Solution
- Make `for_each` compatible with mutable queries, and deprecate
`for_each_mut`. In order to prevent `for_each` from being called
multiple times in parallel, we take ownership of the QueryParIter.
---
## Changelog
- `QueryParIter::for_each` is now compatible with mutable queries.
`for_each_mut` has been deprecated as it is now redundant.
## Migration Guide
The method `QueryParIter::for_each_mut` has been deprecated and is no
longer functional. Use `for_each` instead, which now supports mutable
queries.
```rust
// Before:
query.par_iter_mut().for_each_mut(|x| ...);
// After:
query.par_iter_mut().for_each(|x| ...);
```
The method `QueryParIter::for_each` now takes ownership of the
`QueryParIter`, rather than taking a shared reference.
```rust
// Before:
let par_iter = my_query.par_iter().batching_strategy(my_batching_strategy);
par_iter.for_each(|x| {
// ...Do stuff with x...
par_iter.for_each(|y| {
// ...Do nested stuff with y...
});
});
// After:
my_query.par_iter().batching_strategy(my_batching_strategy).for_each(|x| {
// ...Do stuff with x...
my_query.par_iter().batching_strategy(my_batching_strategy).for_each(|y| {
// ...Do nested stuff with y...
});
});
```
