# Objective
^ enable this
Concretely, I need to
- list all handle ids for an asset type
- fetch the asset as `dyn Reflect`, given a `HandleUntyped`
- when encountering a `Handle<T>`, find out what asset type that handle refers to (`T`'s type id) and turn the handle into a `HandleUntyped`
## Solution
- add `ReflectAsset` type containing function pointers for working with assets
```rust
pub struct ReflectAsset {
type_uuid: Uuid,
assets_resource_type_id: TypeId, // TypeId of the `Assets<T>` resource
get: fn(&World, HandleUntyped) -> Option<&dyn Reflect>,
get_mut: fn(&mut World, HandleUntyped) -> Option<&mut dyn Reflect>,
get_unchecked_mut: unsafe fn(&World, HandleUntyped) -> Option<&mut dyn Reflect>,
add: fn(&mut World, &dyn Reflect) -> HandleUntyped,
set: fn(&mut World, HandleUntyped, &dyn Reflect) -> HandleUntyped,
len: fn(&World) -> usize,
ids: for<'w> fn(&'w World) -> Box<dyn Iterator<Item = HandleId> + 'w>,
remove: fn(&mut World, HandleUntyped) -> Option<Box<dyn Reflect>>,
}
```
- add `ReflectHandle` type relating the handle back to the asset type and providing a way to create a `HandleUntyped`
```rust
pub struct ReflectHandle {
type_uuid: Uuid,
asset_type_id: TypeId,
downcast_handle_untyped: fn(&dyn Any) -> Option<HandleUntyped>,
}
```
- add the corresponding `FromType` impls
- add a function `app.register_asset_reflect` which is supposed to be called after `.add_asset` and registers `ReflectAsset` and `ReflectHandle` in the type registry
---
## Changelog
- add `ReflectAsset` and `ReflectHandle` types, which allow code to use reflection to manipulate arbitrary assets without knowing their types at compile time
# Objective
Bevy's internal plugins have lots of execution-order ambiguities, which makes the ambiguity detection tool very noisy for our users.
## Solution
Silence every last ambiguity that can currently be resolved.
Each time an ambiguity is silenced, it is accompanied by a comment describing why it is correct. This description should be based on the public API of the respective systems. Thus, I have added documentation to some systems describing how they use some resources.
# Future work
Some ambiguities remain, due to issues out of scope for this PR.
* The ambiguity checker does not respect `Without<>` filters, leading to false positives.
* Ambiguities between `bevy_ui` and `bevy_animation` cannot be resolved, since neither crate knows that the other exists. We will need a general solution to this problem.
Attempt to make features like bloom https://github.com/bevyengine/bevy/pull/2876 easier to implement.
**This PR:**
- Moves the tonemapping from `pbr.wgsl` into a separate pass
- also add a separate upscaling pass after the tonemapping which writes to the swap chain (enables resolution-independant rendering and post-processing after tonemapping)
- adds a `hdr` bool to the camera which controls whether the pbr and sprite shaders render into a `Rgba16Float` texture
**Open questions:**
- ~should the 2d graph work the same as the 3d one?~ it is the same now
- ~The current solution is a bit inflexible because while you can add a post processing pass that writes to e.g. the `hdr_texture`, you can't write to a separate `user_postprocess_texture` while reading the `hdr_texture` and tell the tone mapping pass to read from the `user_postprocess_texture` instead. If the tonemapping and upscaling render graph nodes were to take in a `TextureView` instead of the view entity this would almost work, but the bind groups for their respective input textures are already created in the `Queue` render stage in the hardcoded order.~ solved by creating bind groups in render node
**New render graph:**
<details>
<summary>Before</summary>
</details>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Improve ergonomics by passing on the `IntoIterator` impl of the underlying type to wrapper types.
## Solution
Implement `IntoIterator` for ECS wrapper types (Mut, Local, Res, etc.).
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
Use saturate wgsl function now implemented in naga (version 0.10.0). There is now no need for one in utils.wgsl.
naga's version allows usage for not only scalars but vectors as well.
## Solution
Remove the utils.wgsl saturate function.
## Changelog
Remove saturate function from utils.wgsl in favor of saturate in naga v0.10.0.
# Objective
- It's possible to create a mesh without positions or normals, but currently bevy forces these attributes to be present on any mesh.
## Solution
- Don't assume these attributes are present and add a shader defs for each attributes
- I updated 2d and 3d meshes to use the same logic.
---
## Changelog
- Meshes don't require any attributes
# Notes
I didn't update the pbr.wgsl shader because I'm not sure how to handle it. It doesn't really make sense to use it without positions or normals.
# Objective
There is no Srgb support on some GPU and display protocols with `winit` (for example, Nvidia's GPUs with Wayland). Thus `TextureFormat::bevy_default()` which returns `Rgba8UnormSrgb` or `Bgra8UnormSrgb` will cause panics on such platforms. This patch will resolve this problem. Fix https://github.com/bevyengine/bevy/issues/3897.
## Solution
Make `initialize_renderer` expose `wgpu::Adapter` and `first_available_texture_format`, use the `first_available_texture_format` by default.
## Changelog
* Fixed https://github.com/bevyengine/bevy/issues/3897.
# Objective
fix error with pbr shader's spotlight direction calculation when direction.y ~= 0
## Solution
in pbr_lighting.wgsl, clamp `1-x^2-z^2` to `>= 0` so that we can safely `sqrt` it
# Objective
The `Wireframe` type implements `Reflect`, but is never registered, making its reflection inaccessible.
## Solution
Call `App::register_type::<Wireframe>()` in the `Plugin::build` implementation of `WireframePlugin`.
---
## Changelog
Fixed `Wireframe` type reflection not getting registered.
# Objective
Add more documentation on `StandardMaterial` and improve
consistency on existing doc.
Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>
# Objective
- Alpha mask was previously ignored when using an unlit material.
- Fixes https://github.com/bevyengine/bevy/issues/4479
## Solution
- Extract the alpha discard to a separate function and use it when unlit is true
## Notes
I tried calling `alpha_discard()` before the `if` in pbr.wgsl, but I had errors related to having a `discard` at the beginning before doing the texture sampling. I'm not sure if there's a way to fix that instead of having the function being called in 2 places.
# Objective
Simple docs/comments only PR that just fixes some outdated file references left over from the render rewrite.
## Solution
- Change the references to point to the correct files
# Objective
The [Stageless RFC](https://github.com/bevyengine/rfcs/pull/45) involves allowing exclusive systems to be referenced and ordered relative to parallel systems. We've agreed that unifying systems under `System` is the right move.
This is an alternative to #4166 (see rationale in the comments I left there). Note that this builds on the learnings established there (and borrows some patterns).
## Solution
This unifies parallel and exclusive systems under the shared `System` trait, removing the old `ExclusiveSystem` trait / impls. This is accomplished by adding a new `ExclusiveFunctionSystem` impl similar to `FunctionSystem`. It is backed by `ExclusiveSystemParam`, which is similar to `SystemParam`. There is a new flattened out SystemContainer api (which cuts out a lot of trait and type complexity).
This means you can remove all cases of `exclusive_system()`:
```rust
// before
commands.add_system(some_system.exclusive_system());
// after
commands.add_system(some_system);
```
I've also implemented `ExclusiveSystemParam` for `&mut QueryState` and `&mut SystemState`, which makes this possible in exclusive systems:
```rust
fn some_exclusive_system(
world: &mut World,
transforms: &mut QueryState<&Transform>,
state: &mut SystemState<(Res<Time>, Query<&Player>)>,
) {
for transform in transforms.iter(world) {
println!("{transform:?}");
}
let (time, players) = state.get(world);
for player in players.iter() {
println!("{player:?}");
}
}
```
Note that "exclusive function systems" assume `&mut World` is present (and the first param). I think this is a fair assumption, given that the presence of `&mut World` is what defines the need for an exclusive system.
I added some targeted SystemParam `static` constraints, which removed the need for this:
``` rust
fn some_exclusive_system(state: &mut SystemState<(Res<'static, Time>, Query<&'static Player>)>) {}
```
## Related
- #2923
- #3001
- #3946
## Changelog
- `ExclusiveSystem` trait (and implementations) has been removed in favor of sharing the `System` trait.
- `ExclusiveFunctionSystem` and `ExclusiveSystemParam` were added, enabling flexible exclusive function systems
- `&mut SystemState` and `&mut QueryState` now implement `ExclusiveSystemParam`
- Exclusive and parallel System configuration is now done via a unified `SystemDescriptor`, `IntoSystemDescriptor`, and `SystemContainer` api.
## Migration Guide
Calling `.exclusive_system()` is no longer required (or supported) for converting exclusive system functions to exclusive systems:
```rust
// Old (0.8)
app.add_system(some_exclusive_system.exclusive_system());
// New (0.9)
app.add_system(some_exclusive_system);
```
Converting "normal" parallel systems to exclusive systems is done by calling the exclusive ordering apis:
```rust
// Old (0.8)
app.add_system(some_system.exclusive_system().at_end());
// New (0.9)
app.add_system(some_system.at_end());
```
Query state in exclusive systems can now be cached via ExclusiveSystemParams, which should be preferred for clarity and performance reasons:
```rust
// Old (0.8)
fn some_system(world: &mut World) {
let mut transforms = world.query::<&Transform>();
for transform in transforms.iter(world) {
}
}
// New (0.9)
fn some_system(world: &mut World, transforms: &mut QueryState<&Transform>) {
for transform in transforms.iter(world) {
}
}
```
# Objective
Now that we can consolidate Bundles and Components under a single insert (thanks to #2975 and #6039), almost 100% of world spawns now look like `world.spawn().insert((Some, Tuple, Here))`. Spawning an entity without any components is an extremely uncommon pattern, so it makes sense to give spawn the "first class" ergonomic api. This consolidated api should be made consistent across all spawn apis (such as World and Commands).
## Solution
All `spawn` apis (`World::spawn`, `Commands:;spawn`, `ChildBuilder::spawn`, and `WorldChildBuilder::spawn`) now accept a bundle as input:
```rust
// before:
commands
.spawn()
.insert((A, B, C));
world
.spawn()
.insert((A, B, C);
// after
commands.spawn((A, B, C));
world.spawn((A, B, C));
```
All existing instances of `spawn_bundle` have been deprecated in favor of the new `spawn` api. A new `spawn_empty` has been added, replacing the old `spawn` api.
By allowing `world.spawn(some_bundle)` to replace `world.spawn().insert(some_bundle)`, this opened the door to removing the initial entity allocation in the "empty" archetype / table done in `spawn()` (and subsequent move to the actual archetype in `.insert(some_bundle)`).
This improves spawn performance by over 10%:
To take this measurement, I added a new `world_spawn` benchmark.
Unfortunately, optimizing `Commands::spawn` is slightly less trivial, as Commands expose the Entity id of spawned entities prior to actually spawning. Doing the optimization would (naively) require assurances that the `spawn(some_bundle)` command is applied before all other commands involving the entity (which would not necessarily be true, if memory serves). Optimizing `Commands::spawn` this way does feel possible, but it will require careful thought (and maybe some additional checks), which deserves its own PR. For now, it has the same performance characteristics of the current `Commands::spawn_bundle` on main.
**Note that 99% of this PR is simple renames and refactors. The only code that needs careful scrutiny is the new `World::spawn()` impl, which is relatively straightforward, but it has some new unsafe code (which re-uses battle tested BundlerSpawner code path).**
---
## Changelog
- All `spawn` apis (`World::spawn`, `Commands:;spawn`, `ChildBuilder::spawn`, and `WorldChildBuilder::spawn`) now accept a bundle as input
- All instances of `spawn_bundle` have been deprecated in favor of the new `spawn` api
- World and Commands now have `spawn_empty()`, which is equivalent to the old `spawn()` behavior.
## Migration Guide
```rust
// Old (0.8):
commands
.spawn()
.insert_bundle((A, B, C));
// New (0.9)
commands.spawn((A, B, C));
// Old (0.8):
commands.spawn_bundle((A, B, C));
// New (0.9)
commands.spawn((A, B, C));
// Old (0.8):
let entity = commands.spawn().id();
// New (0.9)
let entity = commands.spawn_empty().id();
// Old (0.8)
let entity = world.spawn().id();
// New (0.9)
let entity = world.spawn_empty();
```
# Objective
Take advantage of the "impl Bundle for Component" changes in #2975 / add the follow up changes discussed there.
## Solution
- Change `insert` and `remove` to accept a Bundle instead of a Component (for both Commands and World)
- Deprecate `insert_bundle`, `remove_bundle`, and `remove_bundle_intersection`
- Add `remove_intersection`
---
## Changelog
- Change `insert` and `remove` now accept a Bundle instead of a Component (for both Commands and World)
- `insert_bundle` and `remove_bundle` are deprecated
## Migration Guide
Replace `insert_bundle` with `insert`:
```rust
// Old (0.8)
commands.spawn().insert_bundle(SomeBundle::default());
// New (0.9)
commands.spawn().insert(SomeBundle::default());
```
Replace `remove_bundle` with `remove`:
```rust
// Old (0.8)
commands.entity(some_entity).remove_bundle::<SomeBundle>();
// New (0.9)
commands.entity(some_entity).remove::<SomeBundle>();
```
Replace `remove_bundle_intersection` with `remove_intersection`:
```rust
// Old (0.8)
world.entity_mut(some_entity).remove_bundle_intersection::<SomeBundle>();
// New (0.9)
world.entity_mut(some_entity).remove_intersection::<SomeBundle>();
```
Consider consolidating as many operations as possible to improve ergonomics and cut down on archetype moves:
```rust
// Old (0.8)
commands.spawn()
.insert_bundle(SomeBundle::default())
.insert(SomeComponent);
// New (0.9) - Option 1
commands.spawn().insert((
SomeBundle::default(),
SomeComponent,
))
// New (0.9) - Option 2
commands.spawn_bundle((
SomeBundle::default(),
SomeComponent,
))
```
## Next Steps
Consider changing `spawn` to accept a bundle and deprecate `spawn_bundle`.
# Objective
Implement `IntoIterator` for `&Extract<P>` if the system parameter it wraps implements `IntoIterator`.
Enables the use of `IntoIterator` with an extracted query.
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
fixes#5946
## Solution
adjust cluster index calculation for viewport origin.
from reading point 2 of the rasterization algorithm description in https://gpuweb.github.io/gpuweb/#rasterization, it looks like framebuffer space (and so @bulitin(position)) is not meant to be adjusted for viewport origin, so we need to subtract that to get the right cluster index.
- add viewport origin to rust `ExtractedView` and wgsl `View` structs
- subtract from frag coord for cluster index calculation
# Objective
Since `identity` is a const fn that takes no arguments it seems logical to make it an associated constant.
This is also more in line with types from glam (eg. `Quat::IDENTITY`).
## Migration Guide
The method `identity()` on `Transform`, `GlobalTransform` and `TransformBundle` has been deprecated.
Use the associated constant `IDENTITY` instead.
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
- Morten Mikkelsen clarified that the world normal and tangent must be normalized in the vertex stage and the interpolated values must not be normalized in the fragment stage. This is in order to match the mikktspace approach exactly.
- Fixes#5514 by ensuring the tangent basis matrix (TBN) is orthonormal
## Solution
- Normalize the world normal in the vertex stage and not the fragment stage
- Normalize the world tangent xyz in the vertex stage
- Take into account the sign of the determinant of the local to world matrix when calculating the bitangent
---
## Changelog
- Fixed - scaling a model that uses normal mapping now has correct lighting again
*This PR description is an edited copy of #5007, written by @alice-i-cecile.*
# Objective
Follow-up to https://github.com/bevyengine/bevy/pull/2254. The `Resource` trait currently has a blanket implementation for all types that meet its bounds.
While ergonomic, this results in several drawbacks:
* it is possible to make confusing, silent mistakes such as inserting a function pointer (Foo) rather than a value (Foo::Bar) as a resource
* it is challenging to discover if a type is intended to be used as a resource
* we cannot later add customization options (see the [RFC](https://github.com/bevyengine/rfcs/blob/main/rfcs/27-derive-component.md) for the equivalent choice for Component).
* dependencies can use the same Rust type as a resource in invisibly conflicting ways
* raw Rust types used as resources cannot preserve privacy appropriately, as anyone able to access that type can read and write to internal values
* we cannot capture a definitive list of possible resources to display to users in an editor
## Notes to reviewers
* Review this commit-by-commit; there's effectively no back-tracking and there's a lot of churn in some of these commits.
*ira: My commits are not as well organized :')*
* I've relaxed the bound on Local to Send + Sync + 'static: I don't think these concerns apply there, so this can keep things simple. Storing e.g. a u32 in a Local is fine, because there's a variable name attached explaining what it does.
* I think this is a bad place for the Resource trait to live, but I've left it in place to make reviewing easier. IMO that's best tackled with https://github.com/bevyengine/bevy/issues/4981.
## Changelog
`Resource` is no longer automatically implemented for all matching types. Instead, use the new `#[derive(Resource)]` macro.
## Migration Guide
Add `#[derive(Resource)]` to all types you are using as a resource.
If you are using a third party type as a resource, wrap it in a tuple struct to bypass orphan rules. Consider deriving `Deref` and `DerefMut` to improve ergonomics.
`ClearColor` no longer implements `Component`. Using `ClearColor` as a component in 0.8 did nothing.
Use the `ClearColorConfig` in the `Camera3d` and `Camera2d` components instead.
Co-authored-by: Alice <alice.i.cecile@gmail.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: devil-ira <justthecooldude@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
fix an error in shadow map indexing that occurs when point lights without shadows are used in conjunction with spotlights with shadows
## Solution
calculate point_light_count correctly
# Objective
the bevy pbr shader doesn't handle at all normal maps
if a mesh doesn't have backed tangents. This is a pitfall
(that I fell into) and needs to be documented.
# Solution
Document the behavior. (Also document a few other
`StandardMaterial` fields)
## Changelog
* Add documentation to `emissive`, `normal_map_texture` and `occlusion_texture` fields of `StandardMaterial`.
# Objective
[This unwrap()](de484c1e41/crates/bevy_pbr/src/pbr_material.rs (L195)) in pbr_material.rs will be hit if a StandardMaterial normal_map image has not finished loading, resulting in an error message that is hard to debug.
## Solution
~~This PR improves the error message including a potential indication of why the unwrap() could have panic'd by using expect() instead of unwrap().~~
This PR removes the panic by only proceeding if the image is found.
---
## Changelog
Don't panic when StandardMaterial normal_map images have not finished loading.
# Objective
- Add capability to use `Affine3A`s for some `GlobalTransform`s. This allows affine transformations that are not possible using a single `Transform` such as shear and non-uniform scaling along an arbitrary axis.
- Related to #1755 and #2026
## Solution
- `GlobalTransform` becomes an enum wrapping either a `Transform` or an `Affine3A`.
- The API of `GlobalTransform` is minimized to avoid inefficiency, and to make it clear that operations should be performed using the underlying data types.
- using `GlobalTransform::Affine3A` disables transform propagation, because the main use is for cases that `Transform`s cannot support.
---
## Changelog
- `GlobalTransform`s can optionally support any affine transformation using an `Affine3A`.
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Fixes#4907. Fixes#838. Fixes#5089.
Supersedes #5146. Supersedes #2087. Supersedes #865. Supersedes #5114
Visibility is currently entirely local. Set a parent entity to be invisible, and the children are still visible. This makes it hard for users to hide entire hierarchies of entities.
Additionally, the semantics of `Visibility` vs `ComputedVisibility` are inconsistent across entity types. 3D meshes use `ComputedVisibility` as the "definitive" visibility component, with `Visibility` being just one data source. Sprites just use `Visibility`, which means they can't feed off of `ComputedVisibility` data, such as culling information, RenderLayers, and (added in this pr) visibility inheritance information.
## Solution
Splits `ComputedVisibilty::is_visible` into `ComputedVisibilty::is_visible_in_view` and `ComputedVisibilty::is_visible_in_hierarchy`. For each visible entity, `is_visible_in_hierarchy` is computed by propagating visibility down the hierarchy. The `ComputedVisibility::is_visible()` function combines these two booleans for the canonical "is this entity visible" function.
Additionally, all entities that have `Visibility` now also have `ComputedVisibility`. Sprites, Lights, and UI entities now use `ComputedVisibility` when appropriate.
This means that in addition to visibility inheritance, everything using Visibility now also supports RenderLayers. Notably, Sprites (and other 2d objects) now support `RenderLayers` and work properly across multiple views.
Also note that this does increase the amount of work done per sprite. Bevymark with 100,000 sprites on `main` runs in `0.017612` seconds and this runs in `0.01902`. That is certainly a gap, but I believe the api consistency and extra functionality this buys us is worth it. See [this thread](https://github.com/bevyengine/bevy/pull/5146#issuecomment-1182783452) for more info. Note that #5146 in combination with #5114 _are_ a viable alternative to this PR and _would_ perform better, but that comes at the cost of api inconsistencies and doing visibility calculations in the "wrong" place. The current visibility system does have potential for performance improvements. I would prefer to evolve that one system as a whole rather than doing custom hacks / different behaviors for each feature slice.
Here is a "split screen" example where the left camera uses RenderLayers to filter out the blue sprite.
Note that this builds directly on #5146 and that @james7132 deserves the credit for the baseline visibility inheritance work. This pr moves the inherited visibility field into `ComputedVisibility`, then does the additional work of porting everything to `ComputedVisibility`. See my [comments here](https://github.com/bevyengine/bevy/pull/5146#issuecomment-1182783452) for rationale.
## Follow up work
* Now that lights use ComputedVisibility, VisibleEntities now includes "visible lights" in the entity list. Functionally not a problem as we use queries to filter the list down in the desired context. But we should consider splitting this out into a separate`VisibleLights` collection for both clarity and performance reasons. And _maybe_ even consider scoping `VisibleEntities` down to `VisibleMeshes`?.
* Investigate alternative sprite rendering impls (in combination with visibility system tweaks) that avoid re-generating a per-view fixedbitset of visible entities every frame, then checking each ExtractedEntity. This is where most of the performance overhead lives. Ex: we could generate ExtractedEntities per-view using the VisibleEntities list, avoiding the need for the bitset.
* Should ComputedVisibility use bitflags under the hood? This would cut down on the size of the component, potentially speed up the `is_visible()` function, and allow us to cheaply expand ComputedVisibility with more data (ex: split out local visibility and parent visibility, add more culling classes, etc).
---
## Changelog
* ComputedVisibility now takes hierarchy visibility into account.
* 2D, UI and Light entities now use the ComputedVisibility component.
## Migration Guide
If you were previously reading `Visibility::is_visible` as the "actual visibility" for sprites or lights, use `ComputedVisibilty::is_visible()` instead:
```rust
// before (0.7)
fn system(query: Query<&Visibility>) {
for visibility in query.iter() {
if visibility.is_visible {
log!("found visible entity");
}
}
}
// after (0.8)
fn system(query: Query<&ComputedVisibility>) {
for visibility in query.iter() {
if visibility.is_visible() {
log!("found visible entity");
}
}
}
```
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- Wireframes are currently not rendering on main because they aren't being extracted correctly
## Solution
- Extract the wireframes correctly
# Objective
- Added a bunch of backticks to things that should have them, like equations, abstract variable names,
- Changed all small x, y, and z to capitals X, Y, Z.
This might be more annoying than helpful; Feel free to refuse this PR.
Remove unnecessary calls to `iter()`/`iter_mut()`.
Mainly updates the use of queries in our code, docs, and examples.
```rust
// From
for _ in list.iter() {
for _ in list.iter_mut() {
// To
for _ in &list {
for _ in &mut list {
```
We already enable the pedantic lint [clippy::explicit_iter_loop](https://rust-lang.github.io/rust-clippy/stable/) inside of Bevy. However, this only warns for a few known types from the standard library.
## Note for reviewers
As you can see the additions and deletions are exactly equal.
Maybe give it a quick skim to check I didn't sneak in a crypto miner, but you don't have to torture yourself by reading every line.
I already experienced enough pain making this PR :)
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
- Currently, the `Extract` `RenderStage` is executed on the main world, with the render world available as a resource.
- However, when needing access to resources in the render world (e.g. to mutate them), the only way to do so was to get exclusive access to the whole `RenderWorld` resource.
- This meant that effectively only one extract which wrote to resources could run at a time.
- We didn't previously make `Extract`ing writing to the world a non-happy path, even though we want to discourage that.
## Solution
- Move the extract stage to run on the render world.
- Add the main world as a `MainWorld` resource.
- Add an `Extract` `SystemParam` as a convenience to access a (read only) `SystemParam` in the main world during `Extract`.
## Future work
It should be possible to avoid needing to use `get_or_spawn` for the render commands, since now the `Commands`' `Entities` matches up with the world being executed on.
We need to determine how this interacts with https://github.com/bevyengine/bevy/pull/3519
It's theoretically possible to remove the need for the `value` method on `Extract`. However, that requires slightly changing the `SystemParam` interface, which would make it more complicated. That would probably mess up the `SystemState` api too.
## Todo
I still need to add doc comments to `Extract`.
---
## Changelog
### Changed
- The `Extract` `RenderStage` now runs on the render world (instead of the main world as before).
You must use the `Extract` `SystemParam` to access the main world during the extract phase.
Resources on the render world can now be accessed using `ResMut` during extract.
### Removed
- `Commands::spawn_and_forget`. Use `Commands::get_or_spawn(e).insert_bundle(bundle)` instead
## Migration Guide
The `Extract` `RenderStage` now runs on the render world (instead of the main world as before).
You must use the `Extract` `SystemParam` to access the main world during the extract phase. `Extract` takes a single type parameter, which is any system parameter (such as `Res`, `Query` etc.). It will extract this from the main world, and returns the result of this extraction when `value` is called on it.
For example, if previously your extract system looked like:
```rust
fn extract_clouds(mut commands: Commands, clouds: Query<Entity, With<Cloud>>) {
for cloud in clouds.iter() {
commands.get_or_spawn(cloud).insert(Cloud);
}
}
```
the new version would be:
```rust
fn extract_clouds(mut commands: Commands, mut clouds: Extract<Query<Entity, With<Cloud>>>) {
for cloud in clouds.value().iter() {
commands.get_or_spawn(cloud).insert(Cloud);
}
}
```
The diff is:
```diff
--- a/src/clouds.rs
+++ b/src/clouds.rs
@@ -1,5 +1,5 @@
-fn extract_clouds(mut commands: Commands, clouds: Query<Entity, With<Cloud>>) {
- for cloud in clouds.iter() {
+fn extract_clouds(mut commands: Commands, mut clouds: Extract<Query<Entity, With<Cloud>>>) {
+ for cloud in clouds.value().iter() {
commands.get_or_spawn(cloud).insert(Cloud);
}
}
```
You can now also access resources from the render world using the normal system parameters during `Extract`:
```rust
fn extract_assets(mut render_assets: ResMut<MyAssets>, source_assets: Extract<Res<MyAssets>>) {
*render_assets = source_assets.clone();
}
```
Please note that all existing extract systems need to be updated to match this new style; even if they currently compile they will not run as expected. A warning will be emitted on a best-effort basis if this is not met.
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Bevy requires meshes to include UV coordinates, even if the material does not use any textures, and will fail with an error `ERROR bevy_pbr::material: Mesh is missing requested attribute: Vertex_Uv (MeshVertexAttributeId(2), pipeline type: Some("bevy_pbr::material::MaterialPipeline<bevy_pbr::pbr_material::StandardMaterial>"))` otherwise. The objective of this PR is to permit this.
## Solution
This PR follows the design of #4528, which added support for per-vertex colours. It adds a shader define called VERTEX_UVS which indicates the presence of UV coordinates to the shader.
# Objective
add spotlight support
## Solution / Changelog
- add spotlight angles (inner, outer) to ``PointLight`` struct. emitted light is linearly attenuated from 100% to 0% as angle tends from inner to outer. Direction is taken from the existing transform rotation.
- add spotlight direction (vec3) and angles (f32,f32) to ``GpuPointLight`` struct (60 bytes -> 80 bytes) in ``pbr/render/lights.rs`` and ``mesh_view_bind_group.wgsl``
- reduce no-buffer-support max point light count to 204 due to above
- use spotlight data to attenuate light in ``pbr.wgsl``
- do additional cluster culling on spotlights to minimise cost in ``assign_lights_to_clusters``
- changed one of the lights in the lighting demo to a spotlight
- also added a ``spotlight`` demo - probably not justified but so reviewers can see it more easily
## notes
increasing the size of the GpuPointLight struct on my machine reduces the FPS of ``many_lights -- sphere`` from ~150fps to 140fps.
i thought this was a reasonable tradeoff, and felt better than handling spotlights separately which is possible but would mean introducing a new bind group, refactoring light-assignment code and adding new spotlight-specific code in pbr.wgsl. the FPS impact for smaller numbers of lights should be very small.
the cluster culling strategy reintroduces the cluster aabb code which was recently removed... sorry. the aabb is used to get a cluster bounding sphere, which can then be tested fairly efficiently using the strategy described at the end of https://bartwronski.com/2017/04/13/cull-that-cone/. this works well with roughly cubic clusters (where the cluster z size is close to the same as x/y size), less well for other cases like single Z slice / tiled forward rendering. In the worst case we will end up just keeping the culling of the equivalent point light.
Co-authored-by: François <mockersf@gmail.com>
# Objective
Reduce the boilerplate code needed to make draw order sorting work correctly when queuing items through new common functionality. Also fix several instances in the bevy code-base (mostly examples) where this boilerplate appears to be incorrect.
## Solution
- Moved the logic for handling back-to-front vs front-to-back draw ordering into the PhaseItems by inverting the sort key ordering of Opaque3d and AlphaMask3d. The means that all the standard 3d rendering phases measure distance in the same way. Clients of these structs no longer need to know to negate the distance.
- Added a new utility struct, ViewRangefinder3d, which encapsulates the maths needed to calculate a "distance" from an ExtractedView and a mesh's transform matrix.
- Converted all the occurrences of the distance calculations in Bevy and its examples to use ViewRangefinder3d. Several of these occurrences appear to be buggy because they don't invert the view matrix or don't negate the distance where appropriate. This leads me to the view that Bevy should expose a facility to correctly perform this calculation.
## Migration Guide
Code which creates Opaque3d, AlphaMask3d, or Transparent3d phase items _should_ use ViewRangefinder3d to calculate the distance value.
Code which manually calculated the distance for Opaque3d or AlphaMask3d phase items and correctly negated the z value will no longer depth sort correctly. However, incorrect depth sorting for these types will not impact the rendered output as sorting is only a performance optimisation when drawing with depth-testing enabled. Code which manually calculated the distance for Transparent3d phase items will continue to work as before.
# Objective
We don't have reflection for resources.
## Solution
Introduce reflection for resources.
Continues #3580 (by @Davier), related to #3576.
---
## Changelog
### Added
* Reflection on a resource type (by adding `ReflectResource`):
```rust
#[derive(Reflect)]
#[reflect(Resource)]
struct MyResourse;
```
### Changed
* Rename `ReflectComponent::add_component` into `ReflectComponent::insert_component` for consistency.
## Migration Guide
* Rename `ReflectComponent::add_component` into `ReflectComponent::insert_component`.
# Objective
Transform screen-space coordinates into world space in shaders. (My use case is for generating rays for ray tracing with the same perspective as the 3d camera).
## Solution
Add `inverse_projection` and `inverse_view_proj` fields to shader view uniform
---
## Changelog
### Added
`inverse_projection` and `inverse_view_proj` fields to shader view uniform
## Note
It'd probably be good to double-check that I did the matrix multiplication in the right order for `inverse_proj_view`. Thanks!
* Cleanup redundant code
* Use a type alias to make sure the `caster_query` and
`not_caster_query` really do the same thing and access the same things
**Objective**
Cleanup code that would otherwise be difficult to understand
**Solution**
* `extract_meshes` had two for loops which are functionally identical,
just copy-pasted code. I extracted the common code between the two
and put them into an anonymous function.
* I flattened the tuple literal for the bundle batch, it looks much
less nested and the code is much more readable as a result.
* The parameters of `extract_meshes` were also very daunting, but they
turned out to be the same query repeated twice. I extracted the query
into a type alias.
EDIT: I reworked the PR to **not do anything breaking**, and keep the old allocation behavior. Removing the memorized length was clearly a performance loss, so I kept it.
Removed `const_vec2`/`const_vec3`
and replaced with equivalent `.from_array`.
# Objective
Fixes#5112
## Solution
- `encase` needs to update to `glam` as well. See teoxoy/encase#4 on progress on that.
- `hexasphere` also needs to be updated, see OptimisticPeach/hexasphere#12.
# Objective
Fixes#5153
## Solution
Search for all enums and manually check if they have default impls that can use this new derive.
By my reckoning:
| enum | num |
|-|-|
| total | 159 |
| has default impl | 29 |
| default is unit variant | 23 |
# Objective
This PR reworks Bevy's Material system, making the user experience of defining Materials _much_ nicer. Bevy's previous material system leaves a lot to be desired:
* Materials require manually implementing the `RenderAsset` trait, which involves manually generating the bind group, handling gpu buffer data transfer, looking up image textures, etc. Even the simplest single-texture material involves writing ~80 unnecessary lines of code. This was never the long term plan.
* There are two material traits, which is confusing, hard to document, and often redundant: `Material` and `SpecializedMaterial`. `Material` implicitly implements `SpecializedMaterial`, and `SpecializedMaterial` is used in most high level apis to support both use cases. Most users shouldn't need to think about specialization at all (I consider it a "power-user tool"), so the fact that `SpecializedMaterial` is front-and-center in our apis is a miss.
* Implementing either material trait involves a lot of "type soup". The "prepared asset" parameter is particularly heinous: `&<Self as RenderAsset>::PreparedAsset`. Defining vertex and fragment shaders is also more verbose than it needs to be.
## Solution
Say hello to the new `Material` system:
```rust
#[derive(AsBindGroup, TypeUuid, Debug, Clone)]
#[uuid = "f690fdae-d598-45ab-8225-97e2a3f056e0"]
pub struct CoolMaterial {
#[uniform(0)]
color: Color,
#[texture(1)]
#[sampler(2)]
color_texture: Handle<Image>,
}
impl Material for CoolMaterial {
fn fragment_shader() -> ShaderRef {
"cool_material.wgsl".into()
}
}
```
Thats it! This same material would have required [~80 lines of complicated "type heavy" code](https://github.com/bevyengine/bevy/blob/v0.7.0/examples/shader/shader_material.rs) in the old Material system. Now it is just 14 lines of simple, readable code.
This is thanks to a new consolidated `Material` trait and the new `AsBindGroup` trait / derive.
### The new `Material` trait
The old "split" `Material` and `SpecializedMaterial` traits have been removed in favor of a new consolidated `Material` trait. All of the functions on the trait are optional.
The difficulty of implementing `Material` has been reduced by simplifying dataflow and removing type complexity:
```rust
// Old
impl Material for CustomMaterial {
fn fragment_shader(asset_server: &AssetServer) -> Option<Handle<Shader>> {
Some(asset_server.load("custom_material.wgsl"))
}
fn alpha_mode(render_asset: &<Self as RenderAsset>::PreparedAsset) -> AlphaMode {
render_asset.alpha_mode
}
}
// New
impl Material for CustomMaterial {
fn fragment_shader() -> ShaderRef {
"custom_material.wgsl".into()
}
fn alpha_mode(&self) -> AlphaMode {
self.alpha_mode
}
}
```
Specialization is still supported, but it is hidden by default under the `specialize()` function (more on this later).
### The `AsBindGroup` trait / derive
The `Material` trait now requires the `AsBindGroup` derive. This can be implemented manually relatively easily, but deriving it will almost always be preferable.
Field attributes like `uniform` and `texture` are used to define which fields should be bindings,
what their binding type is, and what index they should be bound at:
```rust
#[derive(AsBindGroup)]
struct CoolMaterial {
#[uniform(0)]
color: Color,
#[texture(1)]
#[sampler(2)]
color_texture: Handle<Image>,
}
```
In WGSL shaders, the binding looks like this:
```wgsl
struct CoolMaterial {
color: vec4<f32>;
};
[[group(1), binding(0)]]
var<uniform> material: CoolMaterial;
[[group(1), binding(1)]]
var color_texture: texture_2d<f32>;
[[group(1), binding(2)]]
var color_sampler: sampler;
```
Note that the "group" index is determined by the usage context. It is not defined in `AsBindGroup`. Bevy material bind groups are bound to group 1.
The following field-level attributes are supported:
* `uniform(BINDING_INDEX)`
* The field will be converted to a shader-compatible type using the `ShaderType` trait, written to a `Buffer`, and bound as a uniform. It can also be derived for custom structs.
* `texture(BINDING_INDEX)`
* This field's `Handle<Image>` will be used to look up the matching `Texture` gpu resource, which will be bound as a texture in shaders. The field will be assumed to implement `Into<Option<Handle<Image>>>`. In practice, most fields should be a `Handle<Image>` or `Option<Handle<Image>>`. If the value of an `Option<Handle<Image>>` is `None`, the new `FallbackImage` resource will be used instead. This attribute can be used in conjunction with a `sampler` binding attribute (with a different binding index).
* `sampler(BINDING_INDEX)`
* Behaves exactly like the `texture` attribute, but sets the Image's sampler binding instead of the texture.
Note that fields without field-level binding attributes will be ignored.
```rust
#[derive(AsBindGroup)]
struct CoolMaterial {
#[uniform(0)]
color: Color,
this_field_is_ignored: String,
}
```
As mentioned above, `Option<Handle<Image>>` is also supported:
```rust
#[derive(AsBindGroup)]
struct CoolMaterial {
#[uniform(0)]
color: Color,
#[texture(1)]
#[sampler(2)]
color_texture: Option<Handle<Image>>,
}
```
This is useful if you want a texture to be optional. When the value is `None`, the `FallbackImage` will be used for the binding instead, which defaults to "pure white".
Field uniforms with the same binding index will be combined into a single binding:
```rust
#[derive(AsBindGroup)]
struct CoolMaterial {
#[uniform(0)]
color: Color,
#[uniform(0)]
roughness: f32,
}
```
In WGSL shaders, the binding would look like this:
```wgsl
struct CoolMaterial {
color: vec4<f32>;
roughness: f32;
};
[[group(1), binding(0)]]
var<uniform> material: CoolMaterial;
```
Some less common scenarios will require "struct-level" attributes. These are the currently supported struct-level attributes:
* `uniform(BINDING_INDEX, ConvertedShaderType)`
* Similar to the field-level `uniform` attribute, but instead the entire `AsBindGroup` value is converted to `ConvertedShaderType`, which must implement `ShaderType`. This is useful if more complicated conversion logic is required.
* `bind_group_data(DataType)`
* The `AsBindGroup` type will be converted to some `DataType` using `Into<DataType>` and stored as `AsBindGroup::Data` as part of the `AsBindGroup::as_bind_group` call. This is useful if data needs to be stored alongside the generated bind group, such as a unique identifier for a material's bind group. The most common use case for this attribute is "shader pipeline specialization".
The previous `CoolMaterial` example illustrating "combining multiple field-level uniform attributes with the same binding index" can
also be equivalently represented with a single struct-level uniform attribute:
```rust
#[derive(AsBindGroup)]
#[uniform(0, CoolMaterialUniform)]
struct CoolMaterial {
color: Color,
roughness: f32,
}
#[derive(ShaderType)]
struct CoolMaterialUniform {
color: Color,
roughness: f32,
}
impl From<&CoolMaterial> for CoolMaterialUniform {
fn from(material: &CoolMaterial) -> CoolMaterialUniform {
CoolMaterialUniform {
color: material.color,
roughness: material.roughness,
}
}
}
```
### Material Specialization
Material shader specialization is now _much_ simpler:
```rust
#[derive(AsBindGroup, TypeUuid, Debug, Clone)]
#[uuid = "f690fdae-d598-45ab-8225-97e2a3f056e0"]
#[bind_group_data(CoolMaterialKey)]
struct CoolMaterial {
#[uniform(0)]
color: Color,
is_red: bool,
}
#[derive(Copy, Clone, Hash, Eq, PartialEq)]
struct CoolMaterialKey {
is_red: bool,
}
impl From<&CoolMaterial> for CoolMaterialKey {
fn from(material: &CoolMaterial) -> CoolMaterialKey {
CoolMaterialKey {
is_red: material.is_red,
}
}
}
impl Material for CoolMaterial {
fn fragment_shader() -> ShaderRef {
"cool_material.wgsl".into()
}
fn specialize(
pipeline: &MaterialPipeline<Self>,
descriptor: &mut RenderPipelineDescriptor,
layout: &MeshVertexBufferLayout,
key: MaterialPipelineKey<Self>,
) -> Result<(), SpecializedMeshPipelineError> {
if key.bind_group_data.is_red {
let fragment = descriptor.fragment.as_mut().unwrap();
fragment.shader_defs.push("IS_RED".to_string());
}
Ok(())
}
}
```
Setting `bind_group_data` is not required for specialization (it defaults to `()`). Scenarios like "custom vertex attributes" also benefit from this system:
```rust
impl Material for CustomMaterial {
fn vertex_shader() -> ShaderRef {
"custom_material.wgsl".into()
}
fn fragment_shader() -> ShaderRef {
"custom_material.wgsl".into()
}
fn specialize(
pipeline: &MaterialPipeline<Self>,
descriptor: &mut RenderPipelineDescriptor,
layout: &MeshVertexBufferLayout,
key: MaterialPipelineKey<Self>,
) -> Result<(), SpecializedMeshPipelineError> {
let vertex_layout = layout.get_layout(&[
Mesh::ATTRIBUTE_POSITION.at_shader_location(0),
ATTRIBUTE_BLEND_COLOR.at_shader_location(1),
])?;
descriptor.vertex.buffers = vec![vertex_layout];
Ok(())
}
}
```
### Ported `StandardMaterial` to the new `Material` system
Bevy's built-in PBR material uses the new Material system (including the AsBindGroup derive):
```rust
#[derive(AsBindGroup, Debug, Clone, TypeUuid)]
#[uuid = "7494888b-c082-457b-aacf-517228cc0c22"]
#[bind_group_data(StandardMaterialKey)]
#[uniform(0, StandardMaterialUniform)]
pub struct StandardMaterial {
pub base_color: Color,
#[texture(1)]
#[sampler(2)]
pub base_color_texture: Option<Handle<Image>>,
/* other fields omitted for brevity */
```
### Ported Bevy examples to the new `Material` system
The overall complexity of Bevy's "custom shader examples" has gone down significantly. Take a look at the diffs if you want a dopamine spike.
Please note that while this PR has a net increase in "lines of code", most of those extra lines come from added documentation. There is a significant reduction
in the overall complexity of the code (even accounting for the new derive logic).
---
## Changelog
### Added
* `AsBindGroup` trait and derive, which make it much easier to transfer data to the gpu and generate bind groups for a given type.
### Changed
* The old `Material` and `SpecializedMaterial` traits have been replaced by a consolidated (much simpler) `Material` trait. Materials no longer implement `RenderAsset`.
* `StandardMaterial` was ported to the new material system. There are no user-facing api changes to the `StandardMaterial` struct api, but it now implements `AsBindGroup` and `Material` instead of `RenderAsset` and `SpecializedMaterial`.
## Migration Guide
The Material system has been reworked to be much simpler. We've removed a lot of boilerplate with the new `AsBindGroup` derive and the `Material` trait is simpler as well!
### Bevy 0.7 (old)
```rust
#[derive(Debug, Clone, TypeUuid)]
#[uuid = "f690fdae-d598-45ab-8225-97e2a3f056e0"]
pub struct CustomMaterial {
color: Color,
color_texture: Handle<Image>,
}
#[derive(Clone)]
pub struct GpuCustomMaterial {
_buffer: Buffer,
bind_group: BindGroup,
}
impl RenderAsset for CustomMaterial {
type ExtractedAsset = CustomMaterial;
type PreparedAsset = GpuCustomMaterial;
type Param = (SRes<RenderDevice>, SRes<MaterialPipeline<Self>>);
fn extract_asset(&self) -> Self::ExtractedAsset {
self.clone()
}
fn prepare_asset(
extracted_asset: Self::ExtractedAsset,
(render_device, material_pipeline): &mut SystemParamItem<Self::Param>,
) -> Result<Self::PreparedAsset, PrepareAssetError<Self::ExtractedAsset>> {
let color = Vec4::from_slice(&extracted_asset.color.as_linear_rgba_f32());
let byte_buffer = [0u8; Vec4::SIZE.get() as usize];
let mut buffer = encase::UniformBuffer::new(byte_buffer);
buffer.write(&color).unwrap();
let buffer = render_device.create_buffer_with_data(&BufferInitDescriptor {
contents: buffer.as_ref(),
label: None,
usage: BufferUsages::UNIFORM | BufferUsages::COPY_DST,
});
let (texture_view, texture_sampler) = if let Some(result) = material_pipeline
.mesh_pipeline
.get_image_texture(gpu_images, &Some(extracted_asset.color_texture.clone()))
{
result
} else {
return Err(PrepareAssetError::RetryNextUpdate(extracted_asset));
};
let bind_group = render_device.create_bind_group(&BindGroupDescriptor {
entries: &[
BindGroupEntry {
binding: 0,
resource: buffer.as_entire_binding(),
},
BindGroupEntry {
binding: 0,
resource: BindingResource::TextureView(texture_view),
},
BindGroupEntry {
binding: 1,
resource: BindingResource::Sampler(texture_sampler),
},
],
label: None,
layout: &material_pipeline.material_layout,
});
Ok(GpuCustomMaterial {
_buffer: buffer,
bind_group,
})
}
}
impl Material for CustomMaterial {
fn fragment_shader(asset_server: &AssetServer) -> Option<Handle<Shader>> {
Some(asset_server.load("custom_material.wgsl"))
}
fn bind_group(render_asset: &<Self as RenderAsset>::PreparedAsset) -> &BindGroup {
&render_asset.bind_group
}
fn bind_group_layout(render_device: &RenderDevice) -> BindGroupLayout {
render_device.create_bind_group_layout(&BindGroupLayoutDescriptor {
entries: &[
BindGroupLayoutEntry {
binding: 0,
visibility: ShaderStages::FRAGMENT,
ty: BindingType::Buffer {
ty: BufferBindingType::Uniform,
has_dynamic_offset: false,
min_binding_size: Some(Vec4::min_size()),
},
count: None,
},
BindGroupLayoutEntry {
binding: 1,
visibility: ShaderStages::FRAGMENT,
ty: BindingType::Texture {
multisampled: false,
sample_type: TextureSampleType::Float { filterable: true },
view_dimension: TextureViewDimension::D2Array,
},
count: None,
},
BindGroupLayoutEntry {
binding: 2,
visibility: ShaderStages::FRAGMENT,
ty: BindingType::Sampler(SamplerBindingType::Filtering),
count: None,
},
],
label: None,
})
}
}
```
### Bevy 0.8 (new)
```rust
impl Material for CustomMaterial {
fn fragment_shader() -> ShaderRef {
"custom_material.wgsl".into()
}
}
#[derive(AsBindGroup, TypeUuid, Debug, Clone)]
#[uuid = "f690fdae-d598-45ab-8225-97e2a3f056e0"]
pub struct CustomMaterial {
#[uniform(0)]
color: Color,
#[texture(1)]
#[sampler(2)]
color_texture: Handle<Image>,
}
```
## Future Work
* Add support for more binding types (cubemaps, buffers, etc). This PR intentionally includes a bare minimum number of binding types to keep "reviewability" in check.
* Consider optionally eliding binding indices using binding names. `AsBindGroup` could pass in (optional?) reflection info as a "hint".
* This would make it possible for the derive to do this:
```rust
#[derive(AsBindGroup)]
pub struct CustomMaterial {
#[uniform]
color: Color,
#[texture]
#[sampler]
color_texture: Option<Handle<Image>>,
alpha_mode: AlphaMode,
}
```
* Or this
```rust
#[derive(AsBindGroup)]
pub struct CustomMaterial {
#[binding]
color: Color,
#[binding]
color_texture: Option<Handle<Image>>,
alpha_mode: AlphaMode,
}
```
* Or even this (if we flip to "include bindings by default")
```rust
#[derive(AsBindGroup)]
pub struct CustomMaterial {
color: Color,
color_texture: Option<Handle<Image>>,
#[binding(ignore)]
alpha_mode: AlphaMode,
}
```
* If we add the option to define custom draw functions for materials (which could be done in a type-erased way), I think that would be enough to support extra non-material bindings. Worth considering!
# Objective
This fixes https://github.com/bevyengine/bevy/issues/5127
## Solution
- Moved texture sample out of branch in `prepare_normal()`.
Co-authored-by: DGriffin91 <github@dgdigital.net>
# Objective
- Make the reusable PBR shading functionality a little more reusable
- Add constructor functions for `StandardMaterial` and `PbrInput` structs to populate them with default values
- Document unclear `PbrInput` members
- Demonstrate how to reuse the bevy PBR shading functionality
- The final important piece from #3969 as the initial shot at making the PBR shader code reusable in custom materials
## Solution
- Add back and rework the 'old' `array_texture` example from pre-0.6.
- Create a custom shader material
- Use a single array texture binding and sampler for the material bind group
- Use a shader that calls `pbr()` from the `bevy_pbr::pbr_functions` import
- Spawn a row of cubes using the custom material
- In the shader, select the array texture layer to sample by using the world position x coordinate modulo the number of array texture layers
<img width="1392" alt="Screenshot 2022-06-23 at 12 28 05" src="https://user-images.githubusercontent.com/302146/175278593-2296f519-f577-4ece-81c0-d842283784a1.png">
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- Allow custom shaders to reuse the HDR results of PBR.
## Solution
- Separate `pbr()` and `tone_mapping()` into 2 functions in `pbr_functions.wgsl`.
# Objective
Update pbr mesh shader to use correct normals for skinned meshes.
## Solution
Only use `mesh_normal_local_to_world` for normals if `SKINNED` is not defined.
