This is a squash-and-rebase of @Ku95's documentation of the new renderer onto the latest `pipelined-rendering` branch.
Original PR is #2884.
Co-authored-by: dataphract <dataphract@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Implement frustum culling for much better performance on more complex scenes. With the Amazon Lumberyard Bistro scene, I was getting roughly 15fps without frustum culling and 60+fps with frustum culling on a MacBook Pro 16 with i9 9980HK 8c/16t CPU and Radeon Pro 5500M.
macOS does weird things with vsync so even though vsync was off, it really looked like sometimes other applications or the desktop window compositor were interfering, but the difference could be even more as I even saw up to 90+fps sometimes.
## Solution
- Until the https://github.com/bevyengine/rfcs/pull/12 RFC is completed, I wanted to implement at least some of the bounding volume functionality we needed to be able to unblock a bunch of rendering features and optimisations such as frustum culling, fitting the directional light orthographic projection to the relevant meshes in the view, clustered forward rendering, etc.
- I have added `Aabb`, `Frustum`, and `Sphere` types with only the necessary intersection tests for the algorithms used. I also added `CubemapFrusta` which contains a `[Frustum; 6]` and can be used by cube maps such as environment maps, and point light shadow maps.
- I did do a bit of benchmarking and optimisation on the intersection tests. I compared the [rafx parallel-comparison bitmask approach](c91bd5fcfd/rafx-visibility/src/geometry/frustum.rs (L64-L92)) with a naïve loop that has an early-out in case of a bounding volume being outside of any one of the `Frustum` planes and found them to be very similar, so I chose the simpler and more readable option. I also compared using Vec3 and Vec3A and it turned out that promoting Vec3s to Vec3A improved performance of the culling significantly due to Vec3A operations using SIMD optimisations where Vec3 uses plain scalar operations.
- When loading glTF models, the vertex attribute accessors generally store the minimum and maximum values, which allows for adding AABBs to meshes loaded from glTF for free.
- For meshes without an AABB (`PbrBundle` deliberately does not have an AABB by default), a system is executed that scans over the vertex positions to find the minimum and maximum values along each axis. This is used to construct the AABB.
- The `Frustum::intersects_obb` and `Sphere::insersects_obb` algorithm is from Foundations of Game Engine Development 2: Rendering by Eric Lengyel. There is no OBB type, yet, rather an AABB and the model matrix are passed in as arguments. This calculates a 'relative radius' of the AABB with respect to the plane normal (the plane normal in the Sphere case being something I came up with as the direction pointing from the centre of the sphere to the centre of the AABB) such that it can then do a sphere-sphere intersection test in practice.
- `RenderLayers` were copied over from the current renderer.
- `VisibleEntities` was copied over from the current renderer and a `CubemapVisibleEntities` was added to support `PointLight`s for now. `VisibleEntities` are added to views (cameras and lights) and contain a `Vec<Entity>` that is populated by culling/visibility systems that run in PostUpdate of the app world, and are iterated over in the render world for, for example, queuing up meshes to be drawn by lights for shadow maps and the main pass for cameras.
- `Visibility` and `ComputedVisibility` components were added. The `Visibility` component is user-facing so that, for example, the entity can be marked as not visible in an editor. `ComputedVisibility` on the other hand is the result of the culling/visibility systems and takes `Visibility` into account. So if an entity is marked as not being visible in its `Visibility` component, that will skip culling/visibility intersection tests and just mark the `ComputedVisibility` as false.
- The `ComputedVisibility` is used to decide which meshes to extract.
- I had to add a way to get the far plane from the `CameraProjection` in order to define an explicit far frustum plane for culling. This should perhaps be optional as it is not always desired and in that case, testing 5 planes instead of 6 is a performance win.
I think that's about all. I discussed some of the design with @cart on Discord already so hopefully it's not too far from being mergeable. It works well at least. 😄
# Objective
Make possible to use wgpu gles backend on in the browser (wasm32 + WebGL2).
## Solution
It is built on top of old @cart patch initializing windows before wgpu. Also:
- initializes wgpu with `Backends::GL` and proper `wgpu::Limits` on wasm32
- changes default texture format to `wgpu::TextureFormat::Rgba8UnormSrgb`
Co-authored-by: Mariusz Kryński <mrk@sed.pl>
## New Features
This adds the following to the new renderer:
* **Shader Assets**
* Shaders are assets again! Users no longer need to call `include_str!` for their shaders
* Shader hot-reloading
* **Shader Defs / Shader Preprocessing**
* Shaders now support `# ifdef NAME`, `# ifndef NAME`, and `# endif` preprocessor directives
* **Bevy RenderPipelineDescriptor and RenderPipelineCache**
* Bevy now provides its own `RenderPipelineDescriptor` and the wgpu version is now exported as `RawRenderPipelineDescriptor`. This allows users to define pipelines with `Handle<Shader>` instead of needing to manually compile and reference `ShaderModules`, enables passing in shader defs to configure the shader preprocessor, makes hot reloading possible (because the descriptor can be owned and used to create new pipelines when a shader changes), and opens the doors to pipeline specialization.
* The `RenderPipelineCache` now handles compiling and re-compiling Bevy RenderPipelineDescriptors. It has internal PipelineLayout and ShaderModule caches. Users receive a `CachedPipelineId`, which can be used to look up the actual `&RenderPipeline` during rendering.
* **Pipeline Specialization**
* This enables defining per-entity-configurable pipelines that specialize on arbitrary custom keys. In practice this will involve specializing based on things like MSAA values, Shader Defs, Bind Group existence, and Vertex Layouts.
* Adds a `SpecializedPipeline` trait and `SpecializedPipelines<MyPipeline>` resource. This is a simple layer that generates Bevy RenderPipelineDescriptors based on a custom key defined for the pipeline.
* Specialized pipelines are also hot-reloadable.
* This was the result of experimentation with two different approaches:
1. **"generic immediate mode multi-key hash pipeline specialization"**
* breaks up the pipeline into multiple "identities" (the core pipeline definition, shader defs, mesh layout, bind group layout). each of these identities has its own key. looking up / compiling a specific version of a pipeline requires composing all of these keys together
* the benefit of this approach is that it works for all pipelines / the pipeline is fully identified by the keys. the multiple keys allow pre-hashing parts of the pipeline identity where possible (ex: pre compute the mesh identity for all meshes)
* the downside is that any per-entity data that informs the values of these keys could require expensive re-hashes. computing each key for each sprite tanked bevymark performance (sprites don't actually need this level of specialization yet ... but things like pbr and future sprite scenarios might).
* this is the approach rafx used last time i checked
2. **"custom key specialization"**
* Pipelines by default are not specialized
* Pipelines that need specialization implement a SpecializedPipeline trait with a custom key associated type
* This allows specialization keys to encode exactly the amount of information required (instead of needing to be a combined hash of the entire pipeline). Generally this should fit in a small number of bytes. Per-entity specialization barely registers anymore on things like bevymark. It also makes things like "shader defs" way cheaper to hash because we can use context specific bitflags instead of strings.
* Despite the extra trait, it actually generally makes pipeline definitions + lookups simpler: managing multiple keys (and making the appropriate calls to manage these keys) was way more complicated.
* I opted for custom key specialization. It performs better generally and in my opinion is better UX. Fortunately the way this is implemented also allows for custom caches as this all builds on a common abstraction: the RenderPipelineCache. The built in custom key trait is just a simple / pre-defined way to interact with the cache
## Callouts
* The SpecializedPipeline trait makes it easy to inherit pipeline configuration in custom pipelines. The changes to `custom_shader_pipelined` and the new `shader_defs_pipelined` example illustrate how much simpler it is to define custom pipelines based on the PbrPipeline.
* The shader preprocessor is currently pretty naive (it just uses regexes to process each line). Ultimately we might want to build a more custom parser for more performance + better error handling, but for now I'm happy to optimize for "easy to implement and understand".
## Next Steps
* Port compute pipelines to the new system
* Add more preprocessor directives (else, elif, import)
* More flexible vertex attribute specialization / enable cheaply specializing on specific mesh vertex layouts
Upgrades both the old and new renderer to wgpu 0.11 (and naga 0.7). This builds on @zicklag's work here #2556.
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
This changes how render logic is composed to make it much more modular. Previously, all extraction logic was centralized for a given "type" of rendered thing. For example, we extracted meshes into a vector of ExtractedMesh, which contained the mesh and material asset handles, the transform, etc. We looked up bindings for "drawn things" using their index in the `Vec<ExtractedMesh>`. This worked fine for built in rendering, but made it hard to reuse logic for "custom" rendering. It also prevented us from reusing things like "extracted transforms" across contexts.
To make rendering more modular, I made a number of changes:
* Entities now drive rendering:
* We extract "render components" from "app components" and store them _on_ entities. No more centralized uber lists! We now have true "ECS-driven rendering"
* To make this perform well, I implemented #2673 in upstream Bevy for fast batch insertions into specific entities. This was merged into the `pipelined-rendering` branch here: #2815
* Reworked the `Draw` abstraction:
* Generic `PhaseItems`: each draw phase can define its own type of "rendered thing", which can define its own "sort key"
* Ported the 2d, 3d, and shadow phases to the new PhaseItem impl (currently Transparent2d, Transparent3d, and Shadow PhaseItems)
* `Draw` trait and and `DrawFunctions` are now generic on PhaseItem
* Modular / Ergonomic `DrawFunctions` via `RenderCommands`
* RenderCommand is a trait that runs an ECS query and produces one or more RenderPass calls. Types implementing this trait can be composed to create a final DrawFunction. For example the DrawPbr DrawFunction is created from the following DrawCommand tuple. Const generics are used to set specific bind group locations:
```rust
pub type DrawPbr = (
SetPbrPipeline,
SetMeshViewBindGroup<0>,
SetStandardMaterialBindGroup<1>,
SetTransformBindGroup<2>,
DrawMesh,
);
```
* The new `custom_shader_pipelined` example illustrates how the commands above can be reused to create a custom draw function:
```rust
type DrawCustom = (
SetCustomMaterialPipeline,
SetMeshViewBindGroup<0>,
SetTransformBindGroup<2>,
DrawMesh,
);
```
* ExtractComponentPlugin and UniformComponentPlugin:
* Simple, standardized ways to easily extract individual components and write them to GPU buffers
* Ported PBR and Sprite rendering to the new primitives above.
* Removed staging buffer from UniformVec in favor of direct Queue usage
* Makes UniformVec much easier to use and more ergonomic. Completely removes the need for custom render graph nodes in these contexts (see the PbrNode and view Node removals and the much simpler call patterns in the relevant Prepare systems).
* Added a many_cubes_pipelined example to benchmark baseline 3d rendering performance and ensure there were no major regressions during this port. Avoiding regressions was challenging given that the old approach of extracting into centralized vectors is basically the "optimal" approach. However thanks to a various ECS optimizations and render logic rephrasing, we pretty much break even on this benchmark!
* Lifetimeless SystemParams: this will be a bit divisive, but as we continue to embrace "trait driven systems" (ex: ExtractComponentPlugin, UniformComponentPlugin, DrawCommand), the ergonomics of `(Query<'static, 'static, (&'static A, &'static B, &'static)>, Res<'static, C>)` were getting very hard to bear. As a compromise, I added "static type aliases" for the relevant SystemParams. The previous example can now be expressed like this: `(SQuery<(Read<A>, Read<B>)>, SRes<C>)`. If anyone has better ideas / conflicting opinions, please let me know!
* RunSystem trait: a way to define Systems via a trait with a SystemParam associated type. This is used to implement the various plugins mentioned above. I also added SystemParamItem and QueryItem type aliases to make "trait stye" ecs interactions nicer on the eyes (and fingers).
* RenderAsset retrying: ensures that render assets are only created when they are "ready" and allows us to create bind groups directly inside render assets (which significantly simplified the StandardMaterial code). I think ultimately we should swap this out on "asset dependency" events to wait for dependencies to load, but this will require significant asset system changes.
* Updated some built in shaders to account for missing MeshUniform fields
Makes some tweaks to the SubApp labeling introduced in #2695:
* Ergonomics improvements
* Removes unnecessary allocation when retrieving subapp label
* Removes the newly added "app macros" crate in favor of bevy_derive
* renamed RenderSubApp to RenderApp
@zicklag (for reference)
This is a rather simple but wide change, and it involves adding a new `bevy_app_macros` crate. Let me know if there is a better way to do any of this!
---
# Objective
- Allow adding and accessing sub-apps by using a label instead of an index
## Solution
- Migrate the bevy label implementation and derive code to the `bevy_utils` and `bevy_macro_utils` crates and then add a new `SubAppLabel` trait to the `bevy_app` crate that is used when adding or getting a sub-app from an app.
This decouples the opinionated "core pipeline" from the new (less opinionated) bevy_render crate. The "core pipeline" is intended to be used by crates like bevy_sprites, bevy_pbr, bevy_ui, and 3rd party crates that extends core rendering functionality.
Makes the "Render App World" directly available to Extract step systems as a `RenderWorld` resource. Prior to this, there was no way to directly read / write render world state during the Extract step. The only way to make changes was through Commands (which were applied at the end of the stage).
```rust
// `thing` is an "app world resource".
fn extract_thing(thing: Res<Thing>, mut render_world: ResMut<RenderWorld>) {
render_world.insert_resource(ExtractedThing::from(thing));
}
```
RenderWorld makes a number of scenarios possible:
* When an extract system does big allocations, it is now possible to reuse them across frames by retrieving old values from RenderWorld (at the cost of reduced parallelism from unique RenderWorld borrows).
* Enables inserting into the same resource across multiple extract systems
* Enables using past RenderWorld state to inform future extract state (this should generally be avoided)
Ultimately this is just a subset of the functionality we want. In the future, it would be great to have "multi-world schedules" to enable fine grained parallelism on the render world during the extract step. But that is a research project that almost certainly won't make it into 0.6. This is a good interim solution that should easily port over to multi-world schedules if/when they land.
