Keeping track of explicit visibility per cluster between frames does not
work with LODs, and leads to worse culling (using the final depth buffer
from the previous frame is more accurate).
Instead, we need to generate a second depth pyramid after the second
raster pass, and then use that in the first culling pass in the next
frame to test if a cluster would have been visible last frame or not.
As part of these changes, the write_index_buffer pass has been folded
into the culling pass for a large performance gain, and to avoid
tracking a lot of extra state that would be needed between passes.
Prepass previous model/view stuff was adapted to work with meshlets as
well.
Also fixed a bug with materials, and other misc improvements.
---------
Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: atlas dostal <rodol@rivalrebels.com>
Co-authored-by: vero <email@atlasdostal.com>
Co-authored-by: Patrick Walton <pcwalton@mimiga.net>
Co-authored-by: Robert Swain <robert.swain@gmail.com>
https://github.com/bevyengine/bevy/assets/2632925/e046205e-3317-47c3-9959-fc94c529f7e0
# Objective
- Adds per-object motion blur to the core 3d pipeline. This is a common
effect used in games and other simulations.
- Partially resolves#4710
## Solution
- This is a post-process effect that uses the depth and motion vector
buffers to estimate per-object motion blur. The implementation is
combined from knowledge from multiple papers and articles. The approach
itself, and the shader are quite simple. Most of the effort was in
wiring up the bevy rendering plumbing, and properly specializing for HDR
and MSAA.
- To work with MSAA, the MULTISAMPLED_SHADING wgpu capability is
required. I've extracted this code from #9000. This is because the
prepass buffers are multisampled, and require accessing with
`textureLoad` as opposed to the widely compatible `textureSample`.
- Added an example to demonstrate the effect of motion blur parameters.
## Future Improvements
- While this approach does have limitations, it's one of the most
commonly used, and is much better than camera motion blur, which does
not consider object velocity. For example, this implementation allows a
dolly to track an object, and that object will remain unblurred while
the background is blurred. The biggest issue with this implementation is
that blur is constrained to the boundaries of objects which results in
hard edges. There are solutions to this by either dilating the object or
the motion vector buffer, or by taking a different approach such as
https://casual-effects.com/research/McGuire2012Blur/index.html
- I'm using a noise PRNG function to jitter samples. This could be
replaced with a blue noise texture lookup or similar, however after
playing with the parameters, it gives quite nice results with 4 samples,
and is significantly better than the artifacts generated when not
jittering.
---
## Changelog
- Added: per-object motion blur. This can be enabled and configured by
adding the `MotionBlurBundle` to a camera entity.
---------
Co-authored-by: Torstein Grindvik <52322338+torsteingrindvik@users.noreply.github.com>
# Objective
Clarify the comment about the camera's coordinate system in
`examples/3d/generate_custom_mesh.rs` by explicitly stating which axes
point where.
Fixes#13018
## Solution
Copy the wording from #13012 into the example.
# Objective
- The docs says the WireframeColor is supposed to override the default
global color but it doesn't.
## Solution
- Use WireframeColor to override global color like docs said it was
supposed to do.
- Updated the example to document this feature
- I also took the opportunity to clean up the code a bit
Fixes#13032
# Objective
When learning about creating meshes in bevy using this example I
couldn't tell which coordinate system bevy uses, which caused confusion
and having to look it up else where.
## Solution
Add a comment that says what coordinate system bevy uses.
[Alpha to coverage] (A2C) replaces alpha blending with a
hardware-specific multisample coverage mask when multisample
antialiasing is in use. It's a simple form of [order-independent
transparency] that relies on MSAA. ["Anti-aliased Alpha Test: The
Esoteric Alpha To Coverage"] is a good summary of the motivation for and
best practices relating to A2C.
This commit implements alpha to coverage support as a new variant for
`AlphaMode`. You can supply `AlphaMode::AlphaToCoverage` as the
`alpha_mode` field in `StandardMaterial` to use it. When in use, the
standard material shader automatically applies the texture filtering
method from ["Anti-aliased Alpha Test: The Esoteric Alpha To Coverage"].
Objects with alpha-to-coverage materials are binned in the opaque pass,
as they're fully order-independent.
The `transparency_3d` example has been updated to feature an object with
alpha to coverage. Happily, the example was already using MSAA.
This is part of #2223, as far as I can tell.
[Alpha to coverage]: https://en.wikipedia.org/wiki/Alpha_to_coverage
[order-independent transparency]:
https://en.wikipedia.org/wiki/Order-independent_transparency
["Anti-aliased Alpha Test: The Esoteric Alpha To Coverage"]:
https://bgolus.medium.com/anti-aliased-alpha-test-the-esoteric-alpha-to-coverage-8b177335ae4f
---
## Changelog
### Added
* The `AlphaMode` enum now supports `AlphaToCoverage`, to provide
limited order-independent transparency when multisample antialiasing is
in use.
I ported the two existing PCF techniques to the cubemap domain as best I
could. Generally, the technique is to create a 2D orthonormal basis
using Gram-Schmidt normalization, then apply the technique over that
basis. The results look fine, though the shadow bias often needs
adjusting.
For comparison, Unity uses a 4-tap pattern for PCF on point lights of
(1, 1, 1), (-1, -1, 1), (-1, 1, -1), (1, -1, -1). I tried this but
didn't like the look, so I went with the design above, which ports the
2D techniques to the 3D domain. There's surprisingly little material on
point light PCF.
I've gone through every example using point lights and verified that the
shadow maps look fine, adjusting biases as necessary.
Fixes#3628.
---
## Changelog
### Added
* Shadows from point lights now support percentage-closer filtering
(PCF), and as a result look less aliased.
### Changed
* `ShadowFilteringMethod::Castano13` and
`ShadowFilteringMethod::Jimenez14` have been renamed to
`ShadowFilteringMethod::Gaussian` and `ShadowFilteringMethod::Temporal`
respectively.
## Migration Guide
* `ShadowFilteringMethod::Castano13` and
`ShadowFilteringMethod::Jimenez14` have been renamed to
`ShadowFilteringMethod::Gaussian` and `ShadowFilteringMethod::Temporal`
respectively.
# Objective
- As @james7132 said [on
Discord](https://discord.com/channels/691052431525675048/692572690833473578/1224626740773523536),
the `close_on_esc` system is forcing `bevy_window` to depend on
`bevy_input`.
- `close_on_esc` is not likely to be used in production, so it arguably
does not have a place in `bevy_window`.
## Solution
- As suggested by @afonsolage, move `close_on_esc` into
`bevy_dev_tools`.
- Add an example to the documentation too.
- Remove `bevy_window`'s dependency on `bevy_input`.
- Add `bevy_reflect`'s `smol_str` feature to `bevy_window` because it
was implicitly depended upon with `bevy_input` before it was removed.
- Remove any usage of `close_on_esc` from the examples.
- `bevy_dev_tools` is not enabled by default. I personally find it
frustrating to run examples with additional features, so I opted to
remove it entirely.
- This is up for discussion if you have an alternate solution.
---
## Changelog
- Moved `bevy_window::close_on_esc` to `bevy_dev_tools::close_on_esc`.
- Removed usage of `bevy_dev_tools::close_on_esc` from all examples.
## Migration Guide
`bevy_window::close_on_esc` has been moved to
`bevy_dev_tools::close_on_esc`. You will first need to enable
`bevy_dev_tools` as a feature in your `Cargo.toml`:
```toml
[dependencies]
bevy = { version = "0.14", features = ["bevy_dev_tools"] }
```
Finally, modify any imports to use `bevy_dev_tools` instead:
```rust
// Old:
// use bevy:🪟:close_on_esc;
// New:
use bevy::dev_tools::close_on_esc;
App::new()
.add_systems(Update, close_on_esc)
// ...
.run();
```
# Objective
- There are several redundant imports in the tests and examples that are
not caught by CI because additional flags need to be passed.
## Solution
- Run `cargo check --workspace --tests` and `cargo check --workspace
--examples`, then fix all warnings.
- Add `test-check` to CI, which will be run in the check-compiles job.
This should catch future warnings for tests. Examples are already
checked, but I'm not yet sure why they weren't caught.
## Discussion
- Should the `--tests` and `--examples` flags be added to CI, so this is
caught in the future?
- If so, #12818 will need to be merged first. It was also a warning
raised by checking the examples, but I chose to split off into a
separate PR.
---------
Co-authored-by: François Mockers <francois.mockers@vleue.com>
# Objective
- Since #12453, `DeterministicRenderingConfig` doesn't do anything
## Solution
- Remove it
---
## Migration Guide
- Removed `DeterministicRenderingConfig`. There shouldn't be any z
fighting anymore in the rendering even without setting
`stable_sort_z_fighting`
# Objective
Fixes issue #12613 - the RNG used in examples is _deterministic_, but
its implementation is not _portable_ across platforms. We want to switch
to using a portable RNG that does not vary across platforms, to ensure
certain examples play out the same way every time.
## Solution
Replace all occurences of `rand::rngs::StdRng` with
`rand_chacha::ChaCha8Rng`, as recommended in issue #12613
---
## Changelog
- Add `rand_chacha` as a new dependency (controversial?)
- Replace all occurences of `rand::rngs::StdRng` with
`rand_chacha::ChaCha8Rng`
# Objective
Fixes#12200 .
## Solution
I added a Hue Trait with the rotate_hue method to enable hue rotation.
Additionally, I modified the implementation of animations in the
animated_material sample.
---
## Changelog
- Added a `Hue` trait to `bevy_color/src/color_ops.rs`.
- Added the `Hue` trait implementation to `Hsla`, `Hsva`, `Hwba`,
`Lcha`, and `Oklcha`.
- Updated animated_material sample.
## Migration Guide
Users of Oklcha need to change their usage to use the with_hue method
instead of the with_h method.
---------
Co-authored-by: Pablo Reinhardt <126117294+pablo-lua@users.noreply.github.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
I was wondering why the `lighting` example was still looking quite
different lately (specifically, the intensity of the green light on the
cube) and noticed that we had one more color change I didn't catch
before.
Prior to the `bevy_color` port, `PINK` was actually "deep pink" from the
css4 spec.
`palettes::css::PINK` is now correctly a lighter pink color defined by
the same spec.
```rust
// Bevy 0.13
pub const PINK: Color = Color::rgb(1.0, 0.08, 0.58);
// Bevy 0.14-dev
pub const PINK: Srgba = Srgba::new(1.0, 0.753, 0.796, 1.0);
pub const DEEP_PINK: Srgba = Srgba::new(1.0, 0.078, 0.576, 1.0);
```
## Solution
Change usages of `css::PINK` to `DEEP_PINK` to restore the examples to
their former colors.
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
- With the recent lighting changes, the default configuration in the
`bloom_3d` example is less clear what bloom actually does
- See [this
screenshot](4fdb1455d5 (r1494648414))
for a comparison.
- `bloom_3d` additionally uses a for-loop to spawn the spheres, which
can be turned into `commands::spawn_batch` call.
- The text is black, which is difficult to see on the gray background.
## Solution
- Increase emmisive values of materials.
- Set text to white.
## Showcase
Before:
<img width="1392" alt="before"
src="https://github.com/bevyengine/bevy/assets/59022059/757057ad-ed9f-4eed-b135-8e2032fcdeb5">
After:
<img width="1392" alt="image"
src="https://github.com/bevyengine/bevy/assets/59022059/3f9dc7a8-94b2-44b9-8ac3-deef1905221b">
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Fixes#12226
Prior to the `bevy_color` port, `DARK GRAY` used to mean "dark grey."
But it is now lighter than `GRAY`, matching the css4 spec.
## Solution
Change usages of `css::DARK_GRAY` to `Color::srgb(0.25, 0.25, 0.25)` to
restore the examples to their former colors.
With one exception: `display_and_visibility`. I think the new color is
an improvement.
## Note
A lot of these examples could use nicer colors. I'm not trying to revamp
everything here.
The css4 palette is truly a horror. See #12176 and #12080 for some
discussion about alternatives.
# Objective
Fixes#12225
Prior to the `bevy_color` port, `GREEN` used to mean "full green." But
it is now a much darker color matching the css1 spec.
## Solution
Change usages of `basic::GREEN` or `css::GREEN` to `LIME` to restore the
examples to their former colors.
This also removes the duplicate definition of `GREEN` from `css`. (it
was already re-exported from `basic`)
## Note
A lot of these examples could use nicer colors. I'm not trying to do
that here.
"Dark Grey" will be tackled separately and has its own tracking issue.
# Objective
Fixes https://github.com/bevyengine/bevy/issues/11157.
## Solution
Stop using `BackgroundColor` as a color tint for `UiImage`. Add a
`UiImage::color` field for color tint instead. Allow a UI node to
simultaneously include a solid-color background and an image, with the
image rendered on top of the background (this is already how it works
for e.g. text).
![2024-02-29_1709239666_563x520](https://github.com/bevyengine/bevy/assets/12173779/ec50c9ef-4c7f-4ab8-a457-d086ce5b3425)
---
## Changelog
- The `BackgroundColor` component now renders a solid-color background
behind `UiImage` instead of tinting its color.
- Removed `BackgroundColor` from `ImageBundle`, `AtlasImageBundle`, and
`ButtonBundle`.
- Added `UiImage::color`.
- Expanded `RenderUiSystem` variants.
- Renamed `bevy_ui::extract_text_uinodes` to `extract_uinodes_text` for
consistency.
## Migration Guide
- `BackgroundColor` no longer tints the color of UI images. Use
`UiImage::color` for that instead.
- For solid color buttons, replace `ButtonBundle { background_color:
my_color.into(), ... }` with `ButtonBundle { image:
UiImage::default().with_color(my_color), ... }`, and update button
interaction systems to use `UiImage::color` instead of `BackgroundColor`
as well.
- `bevy_ui::RenderUiSystem::ExtractNode` has been split into
`ExtractBackgrounds`, `ExtractImages`, `ExtractBorders`, and
`ExtractText`.
- `bevy_ui::extract_uinodes` has been split into
`bevy_ui::extract_uinode_background_colors` and
`bevy_ui::extract_uinode_images`.
- `bevy_ui::extract_text_uinodes` has been renamed to
`extract_uinode_text`.
This is an implementation within `bevy_window::window` that fixes
#12229.
# Objective
Fixes#12229, allow users to retrieve the window's size and physical
size as Vectors without having to manually construct them using
`height()` and `width()` or `physical_height()` and `physical_width()`
## Solution
As suggested in #12229, created two public functions within `window`:
`size() -> Vec` and `physical_size() -> UVec` that return the needed
Vectors ready-to-go.
### Discussion
My first FOSS PRQ ever, so bear with me a bit. I'm new to this.
- I replaced instances of ```Vec2::new(window.width(),
window.height());``` or `UVec2::new(window.physical_width(),
window.physical_height());` within bevy examples be replaced with their
`size()`/`physical_size()` counterparts?
- Discussion within #12229 still holds: should these also be added to
WindowResolution?
Although we cached hashes of `MeshVertexBufferLayout`, we were paying
the cost of `PartialEq` on `InnerMeshVertexBufferLayout` for every
entity, every frame. This patch changes that logic to place
`MeshVertexBufferLayout`s in `Arc`s so that they can be compared and
hashed by pointer. This results in a 28% speedup in the
`queue_material_meshes` phase of `many_cubes`, with frustum culling
disabled.
Additionally, this patch contains two minor changes:
1. This commit flattens the specialized mesh pipeline cache to one level
of hash tables instead of two. This saves a hash lookup.
2. The example `many_cubes` has been given a `--no-frustum-culling`
flag, to aid in benchmarking.
See the Tracy profile:
<img width="1064" alt="Screenshot 2024-02-29 144406"
src="https://github.com/bevyengine/bevy/assets/157897/18632f1d-1fdd-4ac7-90ed-2d10306b2a1e">
## Migration guide
* Duplicate `MeshVertexBufferLayout`s are now combined into a single
object, `MeshVertexBufferLayoutRef`, which contains an
atomically-reference-counted pointer to the layout. Code that was using
`MeshVertexBufferLayout` may need to be updated to use
`MeshVertexBufferLayoutRef` instead.
# Objective
- As part of the migration process we need to a) see the end effect of
the migration on user ergonomics b) check for serious perf regressions
c) actually migrate the code
- To accomplish this, I'm going to attempt to migrate all of the
remaining user-facing usages of `LegacyColor` in one PR, being careful
to keep a clean commit history.
- Fixes#12056.
## Solution
I've chosen to use the polymorphic `Color` type as our standard
user-facing API.
- [x] Migrate `bevy_gizmos`.
- [x] Take `impl Into<Color>` in all `bevy_gizmos` APIs
- [x] Migrate sprites
- [x] Migrate UI
- [x] Migrate `ColorMaterial`
- [x] Migrate `MaterialMesh2D`
- [x] Migrate fog
- [x] Migrate lights
- [x] Migrate StandardMaterial
- [x] Migrate wireframes
- [x] Migrate clear color
- [x] Migrate text
- [x] Migrate gltf loader
- [x] Register color types for reflection
- [x] Remove `LegacyColor`
- [x] Make sure CI passes
Incidental improvements to ease migration:
- added `Color::srgba_u8`, `Color::srgba_from_array` and friends
- added `set_alpha`, `is_fully_transparent` and `is_fully_opaque` to the
`Alpha` trait
- add and immediately deprecate (lol) `Color::rgb` and friends in favor
of more explicit and consistent `Color::srgb`
- standardized on white and black for most example text colors
- added vector field traits to `LinearRgba`: ~~`Add`, `Sub`,
`AddAssign`, `SubAssign`,~~ `Mul<f32>` and `Div<f32>`. Multiplications
and divisions do not scale alpha. `Add` and `Sub` have been cut from
this PR.
- added `LinearRgba` and `Srgba` `RED/GREEN/BLUE`
- added `LinearRgba_to_f32_array` and `LinearRgba::to_u32`
## Migration Guide
Bevy's color types have changed! Wherever you used a
`bevy::render::Color`, a `bevy::color::Color` is used instead.
These are quite similar! Both are enums storing a color in a specific
color space (or to be more precise, using a specific color model).
However, each of the different color models now has its own type.
TODO...
- `Color::rgba`, `Color::rgb`, `Color::rbga_u8`, `Color::rgb_u8`,
`Color::rgb_from_array` are now `Color::srgba`, `Color::srgb`,
`Color::srgba_u8`, `Color::srgb_u8` and `Color::srgb_from_array`.
- `Color::set_a` and `Color::a` is now `Color::set_alpha` and
`Color::alpha`. These are part of the `Alpha` trait in `bevy_color`.
- `Color::is_fully_transparent` is now part of the `Alpha` trait in
`bevy_color`
- `Color::r`, `Color::set_r`, `Color::with_r` and the equivalents for
`g`, `b` `h`, `s` and `l` have been removed due to causing silent
relatively expensive conversions. Convert your `Color` into the desired
color space, perform your operations there, and then convert it back
into a polymorphic `Color` enum.
- `Color::hex` is now `Srgba::hex`. Call `.into` or construct a
`Color::Srgba` variant manually to convert it.
- `WireframeMaterial`, `ExtractedUiNode`, `ExtractedDirectionalLight`,
`ExtractedPointLight`, `ExtractedSpotLight` and `ExtractedSprite` now
store a `LinearRgba`, rather than a polymorphic `Color`
- `Color::rgb_linear` and `Color::rgba_linear` are now
`Color::linear_rgb` and `Color::linear_rgba`
- The various CSS color constants are no longer stored directly on
`Color`. Instead, they're defined in the `Srgba` color space, and
accessed via `bevy::color::palettes::css`. Call `.into()` on them to
convert them into a `Color` for quick debugging use, and consider using
the much prettier `tailwind` palette for prototyping.
- The `LIME_GREEN` color has been renamed to `LIMEGREEN` to comply with
the standard naming.
- Vector field arithmetic operations on `Color` (add, subtract, multiply
and divide by a f32) have been removed. Instead, convert your colors
into `LinearRgba` space, and perform your operations explicitly there.
This is particularly relevant when working with emissive or HDR colors,
whose color channel values are routinely outside of the ordinary 0 to 1
range.
- `Color::as_linear_rgba_f32` has been removed. Call
`LinearRgba::to_f32_array` instead, converting if needed.
- `Color::as_linear_rgba_u32` has been removed. Call
`LinearRgba::to_u32` instead, converting if needed.
- Several other color conversion methods to transform LCH or HSL colors
into float arrays or `Vec` types have been removed. Please reimplement
these externally or open a PR to re-add them if you found them
particularly useful.
- Various methods on `Color` such as `rgb` or `hsl` to convert the color
into a specific color space have been removed. Convert into
`LinearRgba`, then to the color space of your choice.
- Various implicitly-converting color value methods on `Color` such as
`r`, `g`, `b` or `h` have been removed. Please convert it into the color
space of your choice, then check these properties.
- `Color` no longer implements `AsBindGroup`. Store a `LinearRgba`
internally instead to avoid conversion costs.
---------
Co-authored-by: Alice Cecile <alice.i.cecil@gmail.com>
Co-authored-by: Afonso Lage <lage.afonso@gmail.com>
Co-authored-by: Rob Parrett <robparrett@gmail.com>
Co-authored-by: Zachary Harrold <zac@harrold.com.au>
# Objective
Split up from #12017, rename Bevy's direction types.
Currently, Bevy has the `Direction2d`, `Direction3d`, and `Direction3dA`
types, which provide a type-level guarantee that their contained vectors
remain normalized. They can be very useful for a lot of APIs for safety,
explicitness, and in some cases performance, as they can sometimes avoid
unnecessary normalizations.
However, many consider them to be inconvenient to use, and opt for
standard vector types like `Vec3` because of this. One reason is that
the direction type names are a bit long and can be annoying to write (of
course you can use autocomplete, but just typing `Vec3` is still nicer),
and in some intances, the extra characters can make formatting worse.
The naming is also inconsistent with Glam's shorter type names, and
results in names like `Direction3dA`, which (in my opinion) are
difficult to read and even a bit ugly.
This PR proposes renaming the types to `Dir2`, `Dir3`, and `Dir3A`.
These names are nice and easy to write, consistent with Glam, and work
well for variants like the SIMD aligned `Dir3A`. As a bonus, it can also
result in nicer formatting in a lot of cases, which can be seen from the
diff of this PR.
Some examples of what it looks like: (copied from #12017)
```rust
// Before
let ray_cast = RayCast2d::new(Vec2::ZERO, Direction2d::X, 5.0);
// After
let ray_cast = RayCast2d::new(Vec2::ZERO, Dir2::X, 5.0);
```
```rust
// Before (an example using Bevy XPBD)
let hit = spatial_query.cast_ray(
Vec3::ZERO,
Direction3d::X,
f32::MAX,
true,
SpatialQueryFilter::default(),
);
// After
let hit = spatial_query.cast_ray(
Vec3::ZERO,
Dir3::X,
f32::MAX,
true,
SpatialQueryFilter::default(),
);
```
```rust
// Before
self.circle(
Vec3::new(0.0, -2.0, 0.0),
Direction3d::Y,
5.0,
Color::TURQUOISE,
);
// After (formatting is collapsed in this case)
self.circle(Vec3::new(0.0, -2.0, 0.0), Dir3::Y, 5.0, Color::TURQUOISE);
```
## Solution
Rename `Direction2d`, `Direction3d`, and `Direction3dA` to `Dir2`,
`Dir3`, and `Dir3A`.
---
## Migration Guide
The `Direction2d` and `Direction3d` types have been renamed to `Dir2`
and `Dir3`.
## Additional Context
This has been brought up on the Discord a few times, and we had a small
[poll](https://discord.com/channels/691052431525675048/1203087353850364004/1212465038711984158)
on this. `Dir2`/`Dir3`/`Dir3A` was quite unanimously chosen as the best
option, but of course it was a very small poll and inconclusive, so
other opinions are certainly welcome too.
---------
Co-authored-by: IceSentry <c.giguere42@gmail.com>
# Objective
`FromWorld` is often used to group loading and creation of assets for
resources.
With this setup, users often end up repetitively calling
`.resource::<AssetServer>` and `.resource_mut::<Assets<T>>`, and may
have difficulties handling lifetimes of the returned references.
## Solution
Add extension methods to `World` to add and load assets, through a new
extension trait defined in `bevy_asset`.
### Other considerations
* This might be a bit too "magic", as it makes implicit the resource
access.
* We could also implement `DirectAssetAccessExt` on `App`, but it didn't
feel necessary, as `FromWorld` is the principal use-case here.
---
## Changelog
* Add the `DirectAssetAccessExt` trait, which adds the `add_asset`,
`load_asset` and `load_asset_with_settings` method to the `World` type.
# Objective
Split up from #12017, add an aligned version of `Direction3d` for SIMD,
and move direction types out of `primitives`.
## Solution
Add `Direction3dA` and move direction types into a new `direction`
module.
---
## Migration Guide
The `Direction2d`, `Direction3d`, and `InvalidDirectionError` types have
been moved out of `bevy::math::primitives`.
Before:
```rust
use bevy::math::primitives::Direction3d;
```
After:
```rust
use bevy::math::Direction3d;
```
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
- The 3D Lighting example is meant to show using multiple lights in the
same scene.
- It currently looks very dark. (See [this
image](4fdb1455d5 (r1494653511)).)
- Resetting the physical camera properties sets the shutter speed to 1 /
125, even though it initially starts at 1 / 100.
## Solution
- Increase the intensity of all 3 lights in the example.
- Now it is much closer to the example in Bevy 0.12.
- I had to remove the comment explaining the lightbulb equivalent of the
intensities because I don't know how it was calculated. Does anyone know
what light emits 100,000 lumens?
- Set the initial shutter speed to 1 / 125.
## Showcase
Before:
<img width="1392" alt="before"
src="https://github.com/bevyengine/bevy/assets/59022059/ac353e02-58e9-4661-aa6d-e5fdf0dcd2f6">
After:
<img width="1392" alt="after"
src="https://github.com/bevyengine/bevy/assets/59022059/4ff0beb6-0ced-4fb2-a953-04be2c77f437">
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
The migration process for `bevy_color` (#12013) will be fairly involved:
there will be hundreds of affected files, and a large number of APIs.
## Solution
To allow us to proceed granularly, we're going to keep both
`bevy_color::Color` (new) and `bevy_render::Color` (old) around until
the migration is complete.
However, simply doing this directly is confusing! They're both called
`Color`, making it very hard to tell when a portion of the code has been
ported.
As discussed in #12056, by renaming the old `Color` type, we can make it
easier to gradually migrate over, one API at a time.
## Migration Guide
THIS MIGRATION GUIDE INTENTIONALLY LEFT BLANK.
This change should not be shipped to end users: delete this section in
the final migration guide!
---------
Co-authored-by: Alice Cecile <alice.i.cecil@gmail.com>
# Objective
- Example reflection_probe is not frame rate independent
## Solution
- Use time delta to rotate the camera, use the same rotation speed as
the load_gltf example
31d7fcd9cb/examples/3d/load_gltf.rs (L63)
---
# Objective
Move Gizmo examples into the separate directory
Fixes#11899
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Joona Aalto <jondolf.dev@gmail.com>
# Objective
Fixes two small quality issues:
1. With the new default ev100 exposure value, the irradiance intensity
was too low
2. The camera was rotating at a fixed speed (instead of a speed
multiplied by delta time), resulting in frame-rate dependent rotation
speed.
# Objective
Fixes#11846
## Solution
Add a `synchronous_pipeline_compilation ` field to `RenderPlugin`,
defaulting to `false`.
Most of the diff is whitespace.
## Changelog
Added `synchronous_pipeline_compilation ` to `RenderPlugin` for
disabling async pipeline creation.
## Migration Guide
TODO: consider combining this with the guide for #11846
`RenderPlugin` has a new `synchronous_pipeline_compilation ` property.
The default value is `false`. Set this to `true` if you want to retain
the previous synchronous behavior.
---------
Co-authored-by: JMS55 <47158642+JMS55@users.noreply.github.com>
Co-authored-by: François <mockersf@gmail.com>
# Objective
After adding configurable exposure, we set the default ev100 value to
`7` (indoor). This brought us out of sync with Blender's configuration
and defaults. This PR changes the default to `9.7` (bright indoor or
very overcast outdoors), as I calibrated in #11577. This feels like a
very reasonable default.
The other changes generally center around tweaking Bevy's lighting
defaults and examples to play nicely with this number, alongside a few
other tweaks and improvements.
Note that for artistic reasons I have reverted some examples, which
changed to directional lights in #11581, back to point lights.
Fixes#11577
---
## Changelog
- Changed `Exposure::ev100` from `7` to `9.7` to better match Blender
- Renamed `ExposureSettings` to `Exposure`
- `Camera3dBundle` now includes `Exposure` for discoverability
- Bumped `FULL_DAYLIGHT ` and `DIRECT_SUNLIGHT` to represent the
middle-to-top of those ranges instead of near the bottom
- Added new `AMBIENT_DAYLIGHT` constant and set that as the new
`DirectionalLight` default illuminance.
- `PointLight` and `SpotLight` now have a default `intensity` of
1,000,000 lumens. This makes them actually useful in the context of the
new "semi-outdoor" exposure and puts them in the "cinema lighting"
category instead of the "common household light" category. They are also
reasonably close to the Blender default.
- `AmbientLight` default has been bumped from `20` to `80`.
## Migration Guide
- The increased `Exposure::ev100` means that all existing 3D lighting
will need to be adjusted to match (DirectionalLights, PointLights,
SpotLights, EnvironmentMapLights, etc). Or alternatively, you can adjust
the `Exposure::ev100` on your cameras to work nicely with your current
lighting values. If you are currently relying on default intensity
values, you might need to change the intensity to achieve the same
effect. Note that in Bevy 0.12, point/spot lights had a different hard
coded ev100 value than directional lights. In Bevy 0.13, they use the
same ev100, so if you have both in your scene, the _scale_ between these
light types has changed and you will likely need to adjust one or both
of them.
# Objective
Fix https://github.com/bevyengine/bevy/issues/11577.
## Solution
Fix the examples, add a few constants to make setting light values
easier, and change the default lighting settings to be more realistic.
(Now designed for an overcast day instead of an indoor environment)
---
I did not include any example-related changes in here.
## Changelogs (not including breaking changes)
### bevy_pbr
- Added `light_consts` module (included in prelude), which contains
common lux and lumen values for lights.
- Added `AmbientLight::NONE` constant, which is an ambient light with a
brightness of 0.
- Added non-EV100 variants for `ExposureSettings`'s EV100 constants,
which allow easier construction of an `ExposureSettings` from a EV100
constant.
## Breaking changes
### bevy_pbr
The several default lighting values were changed:
- `PointLight`'s default `intensity` is now `2000.0`
- `SpotLight`'s default `intensity` is now `2000.0`
- `DirectionalLight`'s default `illuminance` is now
`light_consts::lux::OVERCAST_DAY` (`1000.`)
- `AmbientLight`'s default `brightness` is now `20.0`
I just implemented this to record a video for the new blog post, but I
figured it would also make a good dedicated example. This also allows us
to remove a lot of code from the 2d/3d gizmo examples since it
supersedes this portion of code.
Depends on: https://github.com/bevyengine/bevy/pull/11699
# Objective
#11431 and #11688 implemented meshing support for Bevy's new geometric
primitives. The next step is to deprecate the shapes in
`bevy_render::mesh::shape` and to later remove them completely for 0.14.
## Solution
Deprecate the shapes and reduce code duplication by utilizing the
primitive meshing API for the old shapes where possible.
Note that some shapes have behavior that can't be exactly reproduced
with the new primitives yet:
- `Box` is more of an AABB with min/max extents
- `Plane` supports a subdivision count
- `Quad` has a `flipped` property
These types have not been changed to utilize the new primitives yet.
---
## Changelog
- Deprecated all shapes in `bevy_render::mesh::shape`
- Changed all examples to use new primitives for meshing
## Migration Guide
Bevy has previously used rendering-specific types like `UVSphere` and
`Quad` for primitive mesh shapes. These have now been deprecated to use
the geometric primitives newly introduced in version 0.13.
Some examples:
```rust
let before = meshes.add(shape::Box::new(5.0, 0.15, 5.0));
let after = meshes.add(Cuboid::new(5.0, 0.15, 5.0));
let before = meshes.add(shape::Quad::default());
let after = meshes.add(Rectangle::default());
let before = meshes.add(shape::Plane::from_size(5.0));
// The surface normal can now also be specified when using `new`
let after = meshes.add(Plane3d::default().mesh().size(5.0, 5.0));
let before = meshes.add(
Mesh::try_from(shape::Icosphere {
radius: 0.5,
subdivisions: 5,
})
.unwrap(),
);
let after = meshes.add(Sphere::new(0.5).mesh().ico(5).unwrap());
```
# Objective
- Fixes#11740
## Solution
- Turned `Mesh::set_indices` into `Mesh::insert_indices` and added
related methods for completeness.
---
## Changelog
- Replaced `Mesh::set_indices(indices: Option<Indices>)` with
`Mesh::insert_indices(indices: Indices)`
- Replaced `Mesh::with_indices(indices: Option<Indices>)` with
`Mesh::with_inserted_indices(indices: Indices)` and
`Mesh::with_removed_indices()` mirroring the API for inserting /
removing attributes.
- Updated the examples and internal uses of the APIs described above.
## Migration Guide
- Use `Mesh::insert_indices` or `Mesh::with_inserted_indices` instead of
`Mesh::set_indices` / `Mesh::with_indices`.
- If you have passed `None` to `Mesh::set_indices` or
`Mesh::with_indices` you should use `Mesh::remove_indices` or
`Mesh::with_removed_indices` instead.
---------
Co-authored-by: François <mockersf@gmail.com>
# Objective
Bevy could benefit from *irradiance volumes*, also known as *voxel
global illumination* or simply as light probes (though this term is not
preferred, as multiple techniques can be called light probes).
Irradiance volumes are a form of baked global illumination; they work by
sampling the light at the centers of each voxel within a cuboid. At
runtime, the voxels surrounding the fragment center are sampled and
interpolated to produce indirect diffuse illumination.
## Solution
This is divided into two sections. The first is copied and pasted from
the irradiance volume module documentation and describes the technique.
The second part consists of notes on the implementation.
### Overview
An *irradiance volume* is a cuboid voxel region consisting of
regularly-spaced precomputed samples of diffuse indirect light. They're
ideal if you have a dynamic object such as a character that can move
about
static non-moving geometry such as a level in a game, and you want that
dynamic object to be affected by the light bouncing off that static
geometry.
To use irradiance volumes, you need to precompute, or *bake*, the
indirect
light in your scene. Bevy doesn't currently come with a way to do this.
Fortunately, [Blender] provides a [baking tool] as part of the Eevee
renderer, and its irradiance volumes are compatible with those used by
Bevy.
The [`bevy-baked-gi`] project provides a tool, `export-blender-gi`, that
can
extract the baked irradiance volumes from the Blender `.blend` file and
package them up into a `.ktx2` texture for use by the engine. See the
documentation in the `bevy-baked-gi` project for more details as to this
workflow.
Like all light probes in Bevy, irradiance volumes are 1×1×1 cubes that
can
be arbitrarily scaled, rotated, and positioned in a scene with the
[`bevy_transform::components::Transform`] component. The 3D voxel grid
will
be stretched to fill the interior of the cube, and the illumination from
the
irradiance volume will apply to all fragments within that bounding
region.
Bevy's irradiance volumes are based on Valve's [*ambient cubes*] as used
in
*Half-Life 2* ([Mitchell 2006], slide 27). These encode a single color
of
light from the six 3D cardinal directions and blend the sides together
according to the surface normal.
The primary reason for choosing ambient cubes is to match Blender, so
that
its Eevee renderer can be used for baking. However, they also have some
advantages over the common second-order spherical harmonics approach:
ambient cubes don't suffer from ringing artifacts, they are smaller (6
colors for ambient cubes as opposed to 9 for spherical harmonics), and
evaluation is faster. A smaller basis allows for a denser grid of voxels
with the same storage requirements.
If you wish to use a tool other than `export-blender-gi` to produce the
irradiance volumes, you'll need to pack the irradiance volumes in the
following format. The irradiance volume of resolution *(Rx, Ry, Rz)* is
expected to be a 3D texture of dimensions *(Rx, 2Ry, 3Rz)*. The
unnormalized
texture coordinate *(s, t, p)* of the voxel at coordinate *(x, y, z)*
with
side *S* ∈ *{-X, +X, -Y, +Y, -Z, +Z}* is as follows:
```text
s = x
t = y + ⎰ 0 if S ∈ {-X, -Y, -Z}
⎱ Ry if S ∈ {+X, +Y, +Z}
⎧ 0 if S ∈ {-X, +X}
p = z + ⎨ Rz if S ∈ {-Y, +Y}
⎩ 2Rz if S ∈ {-Z, +Z}
```
Visually, in a left-handed coordinate system with Y up, viewed from the
right, the 3D texture looks like a stacked series of voxel grids, one
for
each cube side, in this order:
| **+X** | **+Y** | **+Z** |
| ------ | ------ | ------ |
| **-X** | **-Y** | **-Z** |
A terminology note: Other engines may refer to irradiance volumes as
*voxel
global illumination*, *VXGI*, or simply as *light probes*. Sometimes
*light
probe* refers to what Bevy calls a reflection probe. In Bevy, *light
probe*
is a generic term that encompasses all cuboid bounding regions that
capture
indirect illumination, whether based on voxels or not.
Note that, if binding arrays aren't supported (e.g. on WebGPU or WebGL
2),
then only the closest irradiance volume to the view will be taken into
account during rendering.
[*ambient cubes*]:
https://advances.realtimerendering.com/s2006/Mitchell-ShadingInValvesSourceEngine.pdf
[Mitchell 2006]:
https://advances.realtimerendering.com/s2006/Mitchell-ShadingInValvesSourceEngine.pdf
[Blender]: http://blender.org/
[baking tool]:
https://docs.blender.org/manual/en/latest/render/eevee/render_settings/indirect_lighting.html
[`bevy-baked-gi`]: https://github.com/pcwalton/bevy-baked-gi
### Implementation notes
This patch generalizes light probes so as to reuse as much code as
possible between irradiance volumes and the existing reflection probes.
This approach was chosen because both techniques share numerous
similarities:
1. Both irradiance volumes and reflection probes are cuboid bounding
regions.
2. Both are responsible for providing baked indirect light.
3. Both techniques involve presenting a variable number of textures to
the shader from which indirect light is sampled. (In the current
implementation, this uses binding arrays.)
4. Both irradiance volumes and reflection probes require gathering and
sorting probes by distance on CPU.
5. Both techniques require the GPU to search through a list of bounding
regions.
6. Both will eventually want to have falloff so that we can smoothly
blend as objects enter and exit the probes' influence ranges. (This is
not implemented yet to keep this patch relatively small and reviewable.)
To do this, we generalize most of the methods in the reflection probes
patch #11366 to be generic over a trait, `LightProbeComponent`. This
trait is implemented by both `EnvironmentMapLight` (for reflection
probes) and `IrradianceVolume` (for irradiance volumes). Using a trait
will allow us to add more types of light probes in the future. In
particular, I highly suspect we will want real-time reflection planes
for mirrors in the future, which can be easily slotted into this
framework.
## Changelog
> This section is optional. If this was a trivial fix, or has no
externally-visible impact, you can delete this section.
### Added
* A new `IrradianceVolume` asset type is available for baked voxelized
light probes. You can bake the global illumination using Blender or
another tool of your choice and use it in Bevy to apply indirect
illumination to dynamic objects.
# Objective
Split up from #11007, fixing most of the remaining work for #10569.
Implement `Meshable` for `Cuboid`, `Sphere`, `Cylinder`, `Capsule`,
`Torus`, and `Plane3d`. This covers all shapes that Bevy has mesh
structs for in `bevy_render::mesh::shapes`.
`Cone` and `ConicalFrustum` are new shapes, so I can add them in a
follow-up, or I could just add them here directly if that's preferrable.
## Solution
Implement `Meshable` for `Cuboid`, `Sphere`, `Cylinder`, `Capsule`,
`Torus`, and `Plane3d`.
The logic is mostly just a copy of the the existing `bevy_render`
shapes, but `Plane3d` has a configurable surface normal that affects the
orientation. Some property names have also been changed to be more
consistent.
The default values differ from the old shapes to make them a bit more
logical:
- Spheres now have a radius of 0.5 instead of 1.0. The default capsule
is equivalent to the default cylinder with the sphere's halves glued on.
- The inner and outer radius of the torus are now 0.5 and 1.0 instead of
0.5 and 1.5 (i.e. the new minor and major radii are 0.25 and 0.75). It's
double the width of the default cuboid, half of its height, and the
default sphere matches the size of the hole.
- `Cuboid` is 1x1x1 by default unlike the dreaded `Box` which is 2x1x1.
Before, with "old" shapes:
![old](https://github.com/bevyengine/bevy/assets/57632562/733f3dda-258c-4491-8152-9829e056a1a3)
Now, with primitive meshing:
![new](https://github.com/bevyengine/bevy/assets/57632562/5a1af14f-bb98-401d-82cf-de8072fea4ec)
I only changed the `3d_shapes` example to use primitives for now. I can
change them all in this PR or a follow-up though, whichever way is
preferrable.
### Sphere API
Spheres have had separate `Icosphere` and `UVSphere` structs, but with
primitives we only have one `Sphere`.
We need to handle this with builders:
```rust
// Existing structs
let ico = Mesh::try_from(Icophere::default()).unwrap();
let uv = Mesh::from(UVSphere::default());
// Primitives
let ico = Sphere::default().mesh().ico(5).unwrap();
let uv = Sphere::default().mesh().uv(32, 18);
```
We could add methods on `Sphere` directly to skip calling `.mesh()`.
I also added a `SphereKind` enum that can be used with the `kind`
method:
```rust
let ico = Sphere::default()
.mesh()
.kind(SphereKind::Ico { subdivisions: 8 })
.build();
```
The default mesh for a `Sphere` is an icosphere with 5 subdivisions
(like the default `Icosphere`).
---
## Changelog
- Implement `Meshable` and `Default` for `Cuboid`, `Sphere`, `Cylinder`,
`Capsule`, `Torus`, and `Plane3d`
- Use primitives in `3d_shapes` example
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# 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.
The PR is in a reviewable state now in the sense that the basic
implementations are there. There are still some ToDos that I'm aware of:
- [x] docs for all the new structs and traits
- [x] implement `Default` and derive other useful traits for the new
structs
- [x] Take a look at the notes again (Do this after a first round of
reviews)
- [x] Take care of the repetition in the circle drawing functions
---
# Objective
- TLDR: This PR enables us to quickly draw all the newly added
primitives from `bevy_math` in immediate mode with gizmos
- Addresses #10571
## Solution
- This implements the first design idea I had that covered everything
that was mentioned in the Issue
https://github.com/bevyengine/bevy/issues/10571#issuecomment-1863646197
---
## Caveats
- I added the `Primitive(2/3)d` impls for `Direction(2/3)d` to make them
work with the current solution. We could impose less strict requirements
for the gizmoable objects and remove the impls afterwards if the
community doesn't like the current approach.
---
## Changelog
- implement capabilities to draw ellipses on the gizmo in general (this
was required to have some code which is able to draw the ellipse
primitive)
- refactored circle drawing code to use the more general ellipse drawing
code to keep code duplication low
- implement `Primitive2d` for `Direction2d` and impl `Primitive3d` for
`Direction3d`
- implement trait to draw primitives with specialized details with
gizmos
- `GizmoPrimitive2d` for all the 2D primitives
- `GizmoPrimitive3d` for all the 3D primitives
- (question while writing this: Does it actually matter if we split this
in 2D and 3D? I guess it could be useful in the future if we do
something based on the main rendering mode even though atm it's kinda
useless)
---
---------
Co-authored-by: nothendev <borodinov.ilya@gmail.com>
# Objective
Drawing a `Gizmos::circle` whose normal is derived from a Transform's
local axes now requires converting a Vec3 to a Direction3d and
unwrapping the result, and I think we shold move the conversion into
Bevy.
## Solution
We can make
`Transform::{left,right,up,down,forward,back,local_x,local_y,local_z}`
return a Direction3d, because they know that their results will be of
finite non-zero length (roughly 1.0).
---
## Changelog
`Transform::up()` and similar functions now return `Direction3d` instead
of `Vec3`.
## Migration Guide
Callers of `Transform::up()` and similar functions may have to
dereference the returned `Direction3d` to get to the inner `Vec3`.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Joona Aalto <jondolf.dev@gmail.com>
# Objective
Right now, all assets in the main world get extracted and prepared in
the render world (if the asset's using the RenderAssetPlugin). This is
unfortunate for two cases:
1. **TextureAtlas** / **FontAtlas**: This one's huge. The individual
`Image` assets that make up the atlas are cloned and prepared
individually when there's no reason for them to be. The atlas textures
are built on the CPU in the main world. *There can be hundreds of images
that get prepared for rendering only not to be used.*
2. If one loads an Image and needs to transform it in a system before
rendering it, kind of like the [decompression
example](https://github.com/bevyengine/bevy/blob/main/examples/asset/asset_decompression.rs#L120),
there's a price paid for extracting & preparing the asset that's not
intended to be rendered yet.
------
* References #10520
* References #1782
## Solution
This changes the `RenderAssetPersistencePolicy` enum to bitflags. I felt
that the objective with the parameter is so similar in nature to wgpu's
[`TextureUsages`](https://docs.rs/wgpu/latest/wgpu/struct.TextureUsages.html)
and
[`BufferUsages`](https://docs.rs/wgpu/latest/wgpu/struct.BufferUsages.html),
that it may as well be just like that.
```rust
// This asset only needs to be in the main world. Don't extract and prepare it.
RenderAssetUsages::MAIN_WORLD
// Keep this asset in the main world and
RenderAssetUsages::MAIN_WORLD | RenderAssetUsages::RENDER_WORLD
// This asset is only needed in the render world. Remove it from the asset server once extracted.
RenderAssetUsages::RENDER_WORLD
```
### Alternate Solution
I considered introducing a third field to `RenderAssetPersistencePolicy`
enum:
```rust
enum RenderAssetPersistencePolicy {
/// Keep the asset in the main world after extracting to the render world.
Keep,
/// Remove the asset from the main world after extracting to the render world.
Unload,
/// This doesn't need to be in the render world at all.
NoExtract, // <-----
}
```
Functional, but this seemed like shoehorning. Another option is renaming
the enum to something like:
```rust
enum RenderAssetExtractionPolicy {
/// Extract the asset and keep it in the main world.
Extract,
/// Remove the asset from the main world after extracting to the render world.
ExtractAndUnload,
/// This doesn't need to be in the render world at all.
NoExtract,
}
```
I think this last one could be a good option if the bitflags are too
clunky.
## Migration Guide
* `RenderAssetPersistencePolicy::Keep` → `RenderAssetUsage::MAIN_WORLD |
RenderAssetUsage::RENDER_WORLD` (or `RenderAssetUsage::default()`)
* `RenderAssetPersistencePolicy::Unload` →
`RenderAssetUsage::RENDER_WORLD`
* For types implementing the `RenderAsset` trait, change `fn
persistence_policy(&self) -> RenderAssetPersistencePolicy` to `fn
asset_usage(&self) -> RenderAssetUsages`.
* Change any references to `cpu_persistent_access`
(`RenderAssetPersistencePolicy`) to `asset_usage` (`RenderAssetUsage`).
This applies to `Image`, `Mesh`, and a few other types.