10da4dc9ae
# Objective Fixes #9367. Yet another follow-up to #16547. These traits were initially based on `Borrow<Entity>` because that trait was what they were replacing, and it felt close enough in meaning. However, they ultimately don't quite match: `borrow` always returns references, whereas `EntityBorrow` always returns a plain `Entity`. Additionally, `EntityBorrow` can imply that we are borrowing an `Entity` from the ECS, which is not what it does. Due to its safety contract, `TrustedEntityBorrow` is important an important and widely used trait for `EntitySet` functionality. In contrast, the safe `EntityBorrow` does not see much use, because even outside of `EntitySet`-related functionality, it is a better idea to accept `TrustedEntityBorrow` over `EntityBorrow`. Furthermore, as #9367 points out, abstracting over returning `Entity` from pointers/structs that contain it can skip some ergonomic friction. On top of that, there are aspects of #18319 and #18408 that are relevant to naming: We've run into the issue that relying on a type default can switch generic order. This is livable in some contexts, but unacceptable in others. To remedy that, we'd need to switch to a type alias approach: The "defaulted" `Entity` case becomes a `UniqueEntity*`/`Entity*Map`/`Entity*Set` alias, and the base type receives a more general name. `TrustedEntityBorrow` does not mesh clearly with sensible base type names. ## Solution Replace any `EntityBorrow` bounds with `TrustedEntityBorrow`. + Rename them as such: `EntityBorrow` -> `ContainsEntity` `TrustedEntityBorrow` -> `EntityEquivalent` For `EntityBorrow` we produce a change in meaning; We designate it for types that aren't necessarily strict wrappers around `Entity` or some pointer to `Entity`, but rather any of the myriad of types that contain a single associated `Entity`. This pattern can already be seen in the common `entity`/`id` methods across the engine. We do not mean for `ContainsEntity` to be a trait that abstracts input API (like how `AsRef<T>` is often used, f.e.), because eliding `entity()` would be too implicit in the general case. We prefix "Contains" to match the intuition of a struct with an `Entity` field, like some contain a `length` or `capacity`. It gives the impression of structure, which avoids the implication of a relationship to the `ECS`. `HasEntity` f.e. could be interpreted as "a currently live entity", As an input trait for APIs like #9367 envisioned, `TrustedEntityBorrow` is a better fit, because it *does* restrict itself to strict wrappers and pointers. Which is why we replace any `EntityBorrow`/`ContainsEntity` bounds with `TrustedEntityBorrow`/`EntityEquivalent`. Here, the name `EntityEquivalent` is a lot closer to its actual meaning, which is "A type that is both equivalent to an `Entity`, and forms the same total order when compared". Prior art for this is the [`Equivalent`](https://docs.rs/hashbrown/latest/hashbrown/trait.Equivalent.html) trait in `hashbrown`, which utilizes both `Borrow` and `Eq` for its one blanket impl! Given that we lose the `Borrow` moniker, and `Equivalent` can carry various meanings, we expand on the safety comment of `EntityEquivalent` somewhat. That should help prevent the confusion we saw in [#18408](https://github.com/bevyengine/bevy/pull/18408#issuecomment-2742094176). The new name meshes a lot better with the type aliasing approach in #18408, by aligning with the base name `EntityEquivalentHashMap`. For a consistent scheme among all set types, we can use this scheme for the `UniqueEntity*` wrapper types as well! This allows us to undo the switched generic order that was introduced to `UniqueEntityArray` by its `Entity` default. Even without the type aliases, I think these renames are worth doing! ## Migration Guide Any use of `EntityBorrow` becomes `ContainsEntity`. Any use of `TrustedEntityBorrow` becomes `EntityEquivalent`. |
||
|---|---|---|
| .cargo | ||
| .github | ||
| assets | ||
| benches | ||
| crates | ||
| docs | ||
| docs-rs | ||
| docs-template | ||
| errors | ||
| examples | ||
| src | ||
| tests | ||
| tests-integration/simple-ecs-test | ||
| tools | ||
| .gitattributes | ||
| .gitignore | ||
| Cargo.toml | ||
| clippy.toml | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| CREDITS.md | ||
| deny.toml | ||
| LICENSE-APACHE | ||
| LICENSE-MIT | ||
| README.md | ||
| rustfmt.toml | ||
| typos.toml | ||
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.