11817f4ba4
Currently, `MeshUniform`s are rather large: 160 bytes. They're also somewhat expensive to compute, because they involve taking the inverse of a 3x4 matrix. Finally, if a mesh is present in multiple views, that mesh will have a separate `MeshUniform` for each and every view, which is wasteful. This commit fixes these issues by introducing the concept of a *mesh input uniform* and adding a *mesh uniform building* compute shader pass. The `MeshInputUniform` is simply the minimum amount of data needed for the GPU to compute the full `MeshUniform`. Most of this data is just the transform and is therefore only 64 bytes. `MeshInputUniform`s are computed during the *extraction* phase, much like skins are today, in order to avoid needlessly copying transforms around on CPU. (In fact, the render app has been changed to only store the translation of each mesh; it no longer cares about any other part of the transform, which is stored only on the GPU and the main world.) Before rendering, the `build_mesh_uniforms` pass runs to expand the `MeshInputUniform`s to the full `MeshUniform`. The mesh uniform building pass does the following, all on GPU: 1. Copy the appropriate fields of the `MeshInputUniform` to the `MeshUniform` slot. If a single mesh is present in multiple views, this effectively duplicates it into each view. 2. Compute the inverse transpose of the model transform, used for transforming normals. 3. If applicable, copy the mesh's transform from the previous frame for TAA. To support this, we double-buffer the `MeshInputUniform`s over two frames and swap the buffers each frame. The `MeshInputUniform`s for the current frame contain the index of that mesh's `MeshInputUniform` for the previous frame. This commit produces wins in virtually every CPU part of the pipeline: `extract_meshes`, `queue_material_meshes`, `batch_and_prepare_render_phase`, and especially `write_batched_instance_buffer` are all faster. Shrinking the amount of CPU data that has to be shuffled around speeds up the entire rendering process. | Benchmark | This branch | `main` | Speedup | |------------------------|-------------|---------|---------| | `many_cubes -nfc` | 17.259 | 24.529 | 42.12% | | `many_cubes -nfc -vpi` | 302.116 | 312.123 | 3.31% | | `many_foxes` | 3.227 | 3.515 | 8.92% | Because mesh uniform building requires compute shader, and WebGL 2 has no compute shader, the existing CPU mesh uniform building code has been left as-is. Many types now have both CPU mesh uniform building and GPU mesh uniform building modes. Developers can opt into the old CPU mesh uniform building by setting the `use_gpu_uniform_builder` option on `PbrPlugin` to `false`. Below are graphs of the CPU portions of `many-cubes --no-frustum-culling`. Yellow is this branch, red is `main`. `extract_meshes`:  It's notable that we get a small win even though we're now writing to a GPU buffer. `queue_material_meshes`:  There's a bit of a regression here; not sure what's causing it. In any case it's very outweighed by the other gains. `batch_and_prepare_render_phase`:  There's a huge win here, enough to make batching basically drop off the profile. `write_batched_instance_buffer`:  There's a massive improvement here, as expected. Note that a lot of it simply comes from the fact that `MeshInputUniform` is `Pod`. (This isn't a maintainability problem in my view because `MeshInputUniform` is so simple: just 16 tightly-packed words.) ## Changelog ### Added * Per-mesh instance data is now generated on GPU with a compute shader instead of CPU, resulting in rendering performance improvements on platforms where compute shaders are supported. ## Migration guide * Custom render phases now need multiple systems beyond just `batch_and_prepare_render_phase`. Code that was previously creating custom render phases should now add a `BinnedRenderPhasePlugin` or `SortedRenderPhasePlugin` as appropriate instead of directly adding `batch_and_prepare_render_phase`. |
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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 early stages of development. Important features are missing. Documentation is sparse. A new version of Bevy containing breaking changes to the API is released approximately once every 3 months. We provide migration guides, but we can't guarantee migrations will always be easy. Use only if you are willing to work in this environment.
MSRV: Bevy relies heavily on improvements in the Rust language and compiler. As a result, the Minimum Supported Rust Version (MSRV) is generally close to "the latest stable release" of Rust.
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
- Features: A quick overview of Bevy's features.
- News: A development blog that covers our progress, plans and shiny new features.
Docs
- Quick Start Guide: Bevy's official Quick Start Guide. The best place to start learning Bevy.
- Bevy Rust API Docs: Bevy's Rust API docs, which are automatically generated from the doc comments in this repo.
- Official Examples: Bevy's dedicated, runnable examples, which are great for digging into specific concepts.
- Community-Made Learning Resources: More tutorials, documentation, and examples made by the Bevy community.
Community
Before contributing or participating in discussions with the community, you should familiarize yourself with our Code of Conduct.
- Discord: Bevy's official discord server.
- Reddit: Bevy's official subreddit.
- GitHub Discussions: The best place for questions about Bevy, answered right here!
- Bevy Assets: A collection of awesome Bevy projects, tools, plugins and learning materials.
Contributing
If you'd like to help build Bevy, check out the Contributor's Guide. For simple problems, feel free to open an issue or PR and tackle it yourself!
For more complex architecture decisions and experimental mad science, please open an RFC (Request For Comments) so we can brainstorm together effectively!
Getting Started
We recommend checking out the Quick Start Guide for a brief introduction.
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
To draw a window with standard functionality enabled, use:
use bevy::prelude::*;
fn main(){
App::new()
.add_plugins(DefaultPlugins)
.run();
}
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.
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.
Thanks
Bevy is the result of the hard work of many people. A huge thanks to all Bevy contributors, the many open source projects that have come before us, the Rust gamedev ecosystem, and the many libraries we build on.
A huge thanks to Bevy's generous sponsors. Bevy will always be free and open source, but it isn't free to make. Please consider sponsoring our work if you like what we're building.
This project is tested with BrowserStack.
License
Bevy is free, open source and permissively licensed! Except where noted (below and/or in individual files), all code in this repository is dual-licensed under either:
- MIT License (LICENSE-MIT or http://opensource.org/licenses/MIT)
- Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
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.
Some of the engine's code carries additional copyright notices and license terms due to their external origins.
These are generally BSD-like, but exact details vary by crate:
If the README of a crate contains a 'License' header (or similar), the additional copyright notices and license terms applicable to that crate will be listed.
The above licensing requirement still applies to contributions to those crates, and sections of those crates will carry those license terms.
The license field of each crate will also reflect this.
For example, bevy_mikktspace has code under the Zlib license (as well as a copyright notice when choosing the MIT license).
The assets included in this repository (for our examples) typically fall under different open licenses. These will not be included in your game (unless copied in by you), and they are not distributed in the published bevy crates. See CREDITS.md for the details of the licenses of those files.
Your contributions
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.