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Patrick Walton df8ccb8735
Implement PBR anisotropy per KHR_materials_anisotropy. (#13450)
This commit implements support for physically-based anisotropy in Bevy's
`StandardMaterial`, following the specification for the
[`KHR_materials_anisotropy`] glTF extension.

[*Anisotropy*] (not to be confused with [anisotropic filtering]) is a
PBR feature that allows roughness to vary along the tangent and
bitangent directions of a mesh. In effect, this causes the specular
light to stretch out into lines instead of a round lobe. This is useful
for modeling brushed metal, hair, and similar surfaces. Support for
anisotropy is a common feature in major game and graphics engines;
Unity, Unreal, Godot, three.js, and Blender all support it to varying
degrees.

Two new parameters have been added to `StandardMaterial`:
`anisotropy_strength` and `anisotropy_rotation`. Anisotropy strength,
which ranges from 0 to 1, represents how much the roughness differs
between the tangent and the bitangent of the mesh. In effect, it
controls how stretched the specular highlight is. Anisotropy rotation
allows the roughness direction to differ from the tangent of the model.

In addition to these two fixed parameters, an *anisotropy texture* can
be supplied. Such a texture should be a 3-channel RGB texture, where the
red and green values specify a direction vector using the same
conventions as a normal map ([0, 1] color values map to [-1, 1] vector
values), and the the blue value represents the strength. This matches
the format that the [`KHR_materials_anisotropy`] specification requires.
Such textures should be loaded as linear and not sRGB. Note that this
texture does consume one additional texture binding in the standard
material shader.

The glTF loader has been updated to properly parse the
`KHR_materials_anisotropy` extension.

A new example, `anisotropy`, has been added. This example loads and
displays the barn lamp example from the [`glTF-Sample-Assets`]
repository. Note that the textures were rather large, so I shrunk them
down and converted them to a mixture of JPEG and KTX2 format, in the
interests of saving space in the Bevy repository.

[*Anisotropy*]:
https://google.github.io/filament/Filament.md.html#materialsystem/anisotropicmodel

[anisotropic filtering]:
https://en.wikipedia.org/wiki/Anisotropic_filtering

[`KHR_materials_anisotropy`]:
https://github.com/KhronosGroup/glTF/blob/main/extensions/2.0/Khronos/KHR_materials_anisotropy/README.md

[`glTF-Sample-Assets`]:
https://github.com/KhronosGroup/glTF-Sample-Assets/

## Changelog

### Added

* Physically-based anisotropy is now available for materials, which
enhances the look of surfaces such as brushed metal or hair. glTF scenes
can use the new feature with the `KHR_materials_anisotropy` extension.

## Screenshots

With anisotropy:
![Screenshot 2024-05-20
233414](https://github.com/bevyengine/bevy/assets/157897/379f1e42-24e9-40b6-a430-f7d1479d0335)

Without anisotropy:
![Screenshot 2024-05-20
233420](https://github.com/bevyengine/bevy/assets/157897/aa220f05-b8e7-417c-9671-b242d4bf9fc4)
2024-06-03 23:46:06 +00:00
.cargo Add cargo ci alias for ci tool (#13280) 2024-05-13 18:33:47 +00:00
.github Update release workflow pr body (#13274) 2024-05-12 20:51:14 +00:00
assets Implement PBR anisotropy per KHR_materials_anisotropy. (#13450) 2024-06-03 23:46:06 +00:00
benches #12502 Remove limit on RenderLayers. (#13317) 2024-05-16 16:15:47 +00:00
crates Implement PBR anisotropy per KHR_materials_anisotropy. (#13450) 2024-06-03 23:46:06 +00:00
docs Separate state crate (#13216) 2024-05-09 18:06:05 +00:00
docs-template Update wgpu to v0.19.3 and unpin web-sys. (#12247) 2024-03-02 00:44:51 +00:00
errors Remove version field for non-publish crates and update descriptions (#13100) 2024-04-26 11:55:03 +00:00
examples Implement PBR anisotropy per KHR_materials_anisotropy. (#13450) 2024-06-03 23:46:06 +00:00
src Give alt text to Bevy logo (#13205) 2024-05-03 19:50:17 +00:00
tests Fixes #12000: When viewport is set to camera and switched to SizedFul… (#12861) 2024-04-06 02:22:50 +00:00
tools Regenerate light cluster patch file (#13655) 2024-06-03 18:19:32 +00:00
.gitattributes Enforce linux-style line endings for .rs and .toml (#3197) 2021-11-26 21:05:35 +00:00
.gitignore Use folder for example showcase reports and add show logs flag (#13198) 2024-05-03 13:03:06 +00:00
Cargo.toml Implement PBR anisotropy per KHR_materials_anisotropy. (#13450) 2024-06-03 23:46:06 +00:00
CHANGELOG.md 0.13 changelog (#11918) 2024-02-17 07:22:02 +00:00
clippy.toml Fix beta lints (#12980) 2024-04-16 02:46:46 +00:00
CODE_OF_CONDUCT.md Update CODE_OF_CONDUCT.md 2020-08-19 20:25:58 +01:00
CONTRIBUTING.md Add a process for working groups (#13162) 2024-05-03 01:01:42 +00:00
CREDITS.md Programmed soundtrack example (#12774) 2024-03-29 20:32:30 +00:00
deny.toml Fix duplicate dependencies on raw-window-handle (#12309) 2024-03-05 08:24:37 +00:00
LICENSE-APACHE Let the project page support GitHub's new ability to display open source licenses (#4966) 2022-06-08 17:55:57 +00:00
LICENSE-MIT Let the project page support GitHub's new ability to display open source licenses (#4966) 2022-06-08 17:55:57 +00:00
README.md Update funding link (#12425) 2024-03-11 21:46:04 +00:00
rustfmt.toml Cargo fmt with unstable features (#1903) 2021-04-21 23:19:34 +00:00
typos.toml Implement PBR anisotropy per KHR_materials_anisotropy. (#13450) 2024-06-03 23:46:06 +00:00

Bevy

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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

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:

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.