75130bd5ec
# Objective > This PR is based on discussion from #6601 The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as both: 1. Dynamic containers which may hold any arbitrary data 2. Proxy types which may represent any other type Currently, the only way we can represent the proxy-ness of a Dynamic is by giving it a name. ```rust // This is just a dynamic container let mut data = DynamicStruct::default(); // This is a "proxy" data.set_name(std::any::type_name::<Foo>()); ``` This type name is the only way we check that the given Dynamic is a proxy of some other type. When we need to "assert the type" of a `dyn Reflect`, we call `Reflect::type_name` on it. However, because we're only using a string to denote the type, we run into a few gotchas and limitations. For example, hashing a Dynamic proxy may work differently than the type it proxies: ```rust #[derive(Reflect, Hash)] #[reflect(Hash)] struct Foo(i32); let concrete = Foo(123); let dynamic = concrete.clone_dynamic(); let concrete_hash = concrete.reflect_hash(); let dynamic_hash = dynamic.reflect_hash(); // The hashes are not equal because `concrete` uses its own `Hash` impl // while `dynamic` uses a reflection-based hashing algorithm assert_ne!(concrete_hash, dynamic_hash); ``` Because the Dynamic proxy only knows about the name of the type, it's unaware of any other information about it. This means it also differs on `Reflect::reflect_partial_eq`, and may include ignored or skipped fields in places the concrete type wouldn't. ## Solution Rather than having Dynamics pass along just the type name of proxied types, we can instead have them pass around the `TypeInfo`. Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than a `String`: ```diff pub struct DynamicTupleStruct { - type_name: String, + represented_type: Option<&'static TypeInfo>, fields: Vec<Box<dyn Reflect>>, } ``` By changing `Reflect::get_type_info` to `Reflect::represented_type_info`, hopefully we make this behavior a little clearer. And to account for `None` values on these dynamic types, `Reflect::represented_type_info` now returns `Option<&'static TypeInfo>`. ```rust let mut data = DynamicTupleStruct::default(); // Not proxying any specific type assert!(dyn_tuple_struct.represented_type_info().is_none()); let type_info = <Foo as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); // Alternatively: // let dyn_tuple_struct = foo.clone_dynamic(); // Now we're proxying `Foo` assert!(dyn_tuple_struct.represented_type_info().is_some()); ``` This means that we can have full access to all the static type information for the proxied type. Future work would include transitioning more static type information (trait impls, attributes, etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic proxies. ### Alternatives & Rationale > **Note** > These alternatives were written when this PR was first made using a `Proxy` trait. This trait has since been removed. <details> <summary>View</summary> #### Alternative: The `Proxy<T>` Approach I had considered adding something like a `Proxy<T>` type where `T` would be the Dynamic and would contain the proxied type information. This was nice in that it allows us to explicitly determine whether something is a proxy or not at a type level. `Proxy<DynamicStruct>` proxies a struct. Makes sense. The reason I didn't go with this approach is because (1) tuples, (2) complexity, and (3) `PartialReflect`. The `DynamicTuple` struct allows us to represent tuples at runtime. It also allows us to do something you normally can't with tuples: add new fields. Because of this, adding a field immediately invalidates the proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32, NewField)`). By going with this PR's approach, we can just remove the type info on `DynamicTuple` when that happens. However, with the `Proxy<T>` approach, it becomes difficult to represent this behavior— we'd have to completely control how we access data for `T` for each `T`. Secondly, it introduces some added complexities (aside from the manual impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we want to represent it as `dyn Reflect`. What `TypeInfo` do we give it? How would we forward reflection methods to the inner type (remember, we don't have specialization)? How do we separate this from Dynamic types? And finally, how do all this in a way that's both logical and intuitive for users? Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is actually more inline with the [Unique Reflect RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy` trait is really one part of the `PartialReflect` trait introduced in that RFC (it's technically not in that RFC but it fits well with it), where the `PartialReflect` serves as a way for proxies to work _like_ concrete types without having full access to everything a concrete `Reflect` type can do. This would help bridge the gap between the current state of the crate and the implementation of that RFC. All that said, this is still a viable solution. If the community believes this is the better path forward, then we can do that instead. These were just my reasons for not initially going with it in this PR. #### Alternative: The Type Registry Approach The `Proxy` trait is great and all, but how does it solve the original problem? Well, it doesn't— yet! The goal would be to start moving information from the derive macro and its attributes to the generated `TypeInfo` since these are known statically and shouldn't change. For example, adding `ignored: bool` to `[Un]NamedField` or a list of impls. However, there is another way of storing this information. This is, of course, one of the uses of the `TypeRegistry`. If we're worried about Dynamic proxies not aligning with their concrete counterparts, we could move more type information to the registry and require its usage. For example, we could replace `Reflect::reflect_hash(&self)` with `Reflect::reflect_hash(&self, registry: &TypeRegistry)`. That's not the _worst_ thing in the world, but it is an ergonomics loss. Additionally, other attributes may have their own requirements, further restricting what's possible without the registry. The `Reflect::apply` method will require the registry as well now. Why? Well because the `map_apply` function used for the `Reflect::apply` impls on `Map` types depends on `Map::insert_boxed`, which (at least for `DynamicMap`) requires `Reflect::reflect_hash`. The same would apply when adding support for reflection-based diffing, which will require `Reflect::reflect_partial_eq`. Again, this is a totally viable alternative. I just chose not to go with it for the reasons above. If we want to go with it, then we can close this PR and we can pursue this alternative instead. #### Downsides Just to highlight a quick potential downside (likely needs more investigation): retrieving the `TypeInfo` requires acquiring a lock on the `GenericTypeInfoCell` used by the `Typed` impls for generic types (non-generic types use a `OnceBox which should be faster). I am not sure how much of a performance hit that is and will need to run some benchmarks to compare against. </details> ### Open Questions 1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be easier for modding? Perhaps, in that case, we need to update `Typed::type_info` and friends as well? 2. Are the alternatives better than the approach this PR takes? Are there other alternatives? --- ## Changelog ### Changed - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` - This method now returns `Option<&'static TypeInfo>` rather than just `&'static TypeInfo` ### Added - Added `Reflect::is_dynamic` method to indicate when a type is dynamic - Added a `set_represented_type` method on all dynamic types ### Removed - Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead) - Removed `Typed` impls for all dynamic types ## Migration Guide - The Dynamic types no longer take a string type name. Instead, they require a static reference to `TypeInfo`: ```rust #[derive(Reflect)] struct MyTupleStruct(f32, f32); let mut dyn_tuple_struct = DynamicTupleStruct::default(); dyn_tuple_struct.insert(1.23_f32); dyn_tuple_struct.insert(3.21_f32); // BEFORE: let type_name = std::any::type_name::<MyTupleStruct>(); dyn_tuple_struct.set_name(type_name); // AFTER: let type_info = <MyTupleStruct as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); ``` - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` and now also returns an `Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`): ```rust // BEFORE: let info: &'static TypeInfo = value.get_type_info(); // AFTER: let info: &'static TypeInfo = value.represented_type_info().unwrap(); ``` - `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use `Reflect::is_dynamic` instead: ```rust // BEFORE: if matches!(value.get_type_info(), TypeInfo::Dynamic) { // ... } // AFTER: if value.is_dynamic() { // ... } ``` --------- Co-authored-by: radiish <cb.setho@gmail.com> |
||
|---|---|---|
| .cargo | ||
| .github | ||
| assets | ||
| benches | ||
| crates | ||
| docs | ||
| docs-template | ||
| errors | ||
| examples | ||
| src | ||
| tests | ||
| tools | ||
| .gitattributes | ||
| .gitignore | ||
| Cargo.toml | ||
| CHANGELOG.md | ||
| clippy.toml | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| CREDITS.md | ||
| deny.toml | ||
| LICENSE-APACHE | ||
| LICENSE-MIT | ||
| README.md | ||
| rustfmt.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 "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
- The Bevy Book: Bevy's official documentation. 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.
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 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
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.
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
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, Fyrox, 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.
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.