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Robert Swain bc5916cce7 Frustum culling (#2861)
# 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. 😄
2021-11-07 21:45:52 +00:00
.cargo Removed irrelevant note for Mac users (#2017) 2021-04-27 00:46:41 +00:00
.github Update for edition 2021 (#2997) 2021-10-25 18:00:13 +00:00
assets Pipeline Specialization, Shader Assets, and Shader Preprocessing (#3031) 2021-10-28 19:07:47 +00:00
benches Update for edition 2021 (#2997) 2021-10-25 18:00:13 +00:00
crates Add System Command apply and RenderGraph node spans (#3069) 2021-11-06 20:15:36 +00:00
docs Relicense Bevy under the dual MIT or Apache-2.0 license (#2509) 2021-07-23 21:11:51 +00:00
examples Sprite Batching (#3060) 2021-11-04 20:28:53 +00:00
pipelined Frustum culling (#2861) 2021-11-07 21:45:52 +00:00
src pipelined rendering proof of concept 2021-07-24 16:43:37 -07:00
tests examples on how to tests systems (#1714) 2021-04-15 00:57:37 +00:00
tools Update for edition 2021 (#2997) 2021-10-25 18:00:13 +00:00
.gitignore add .cargo/config.toml to .gitignore 2020-12-12 17:17:35 -08:00
Cargo.toml MSAA example (#3049) 2021-11-03 22:20:23 +00:00
CHANGELOG.md update CHANGELOG for 0.5 (#1967) 2021-04-19 22:41:19 +00:00
CODE_OF_CONDUCT.md Update CODE_OF_CONDUCT.md 2020-08-19 20:25:58 +01:00
CREDITS.md Cleanup of Markdown Files and add CI Checking (#1463) 2021-02-22 04:50:05 +00:00
deny.toml add proc-macro-crate as a known duplicate (#2456) 2021-07-13 21:51:44 +00:00
LICENSE Relicense Bevy under the dual MIT or Apache-2.0 license (#2509) 2021-07-23 21:11:51 +00:00
README.md Relicense Bevy under the dual MIT or Apache-2.0 license (#2509) 2021-07-23 21:11:51 +00:00
rustfmt.toml Cargo fmt with unstable features (#1903) 2021-04-21 23:19:34 +00:00

Bevy

Crates.io MIT/Apache 2.0 Crates.io Rust iOS cron CI Discord

What is Bevy?

Bevy is a refreshingly simple data-driven game engine built in Rust. It is free and open-source forever!

WARNING

Bevy is still in the very early stages of development. APIs can and will change (now is the time to make suggestions!). Important features are missing. Documentation is sparse. Please don't build any serious projects in Bevy unless you are prepared to be broken by API changes constantly.

Design Goals

  • Capable: Offer a complete 2D and 3D feature set
  • Simple: Easy for newbies to pick up, but infinitely flexible for power users
  • Data Focused: Data-oriented architecture using the Entity Component System paradigm
  • Modular: Use only what you need. Replace what you don't like
  • Fast: App logic should run quickly, and when possible, in parallel
  • Productive: Changes should compile quickly ... waiting isn't fun

About

Docs

Community

Before contributing or participating in discussions with the community, you should familiarize yourself with our Code of Conduct and How to Contribute

Getting Started

We recommend checking out The Bevy Book for a full tutorial.

Follow the Setup guide to ensure your development environment is set up correctly. Once set up, you can quickly try out the examples by cloning this repo and running the following commands:

# Switch to the correct version (latest release, default is main development branch)
git checkout latest
# Runs the "breakout" example
cargo run --example breakout

Fast Compiles

Bevy can be built just fine using default configuration on stable Rust. However for really fast iterative compiles, you should enable the "fast compiles" setup by following the instructions here.

Focus Areas

Bevy has the following Focus Areas. We are currently focusing our development efforts in these areas, and they will receive priority for Bevy developers' time. If you would like to contribute to Bevy, you are heavily encouraged to join in on these efforts:

Editor-Ready UI

PBR / Clustered Forward Rendering

Scenes

Libraries Used

Bevy is only possible because of the hard work put into these foundational technologies:

  • wgpu: modern / low-level / cross-platform graphics library inspired by Vulkan
  • glam-rs: a simple and fast 3D math library for games and graphics
  • winit: cross-platform window creation and management in Rust
  • spirv-reflect: Reflection API in rust for SPIR-V shader byte code

Bevy Cargo Features

This list outlines the different cargo features supported by Bevy. These allow you to customize the Bevy feature set for your use-case.

Third Party Plugins

Plugins are very welcome to extend Bevy's features. Guidelines are available to help integration and usage.

Thanks and Alternatives

Additionally, we would like to thank the Amethyst, macroquad, coffee, ggez, rg3d, and Piston projects for providing solid examples of game engine development in Rust. If you are looking for a Rust game engine, it is worth considering all of your options. Each engine has different design goals, and some will likely resonate with you more than others.

License

Bevy is free and open source! All code in this repository is dual-licensed under either:

at your option. This means you can select the license you prefer! This dual-licensing approach is the de-facto standard in the Rust ecosystem and there are very good reasons to include both.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.