# Dexterous Developer
An experimental hot reload system for the bevy game engine. Inspired by [DGriffin91's Ridiculous bevy hot reloading](https://github.com/DGriffin91/ridiculous_bevy_hot_reloading), it aims to resolve two particular problems I had with it: the ability to re-load arbitrary systems, and then ability to transform resource/component structures over time.
## Features
- Define the reloadable areas of your game explicitly - which can include systems, components and resources (w/ some limitations)
- Reset resources to a default or pre-determined value upon reload
- serialize/deserialize your reloadable resources & components, allowing you to evolve their schemas so long as they are compatible with the de-serializer (using rmp_serde)
- mark entities to get removed on hot reload
- run systems after hot-reload
- create functions to set-up & tear down upon either entering/exiting a state or on hot reload
- default to bypassing hot reload - only add the costs of hot reload during development, using the "hot" feature
## Known issues
- Won't work on mobile or WASM, and only tested on Windows
- events and states still need to be pre-defined
- can't guarantee the main bevy thread will run on the main thread from an OS perspective, which can cause issues in some packages
- Relies on a fork of bevy_winit (only when hot reload is enabled, will use the regular bevy_winit otherwise). A PR for adding the required ability to bevy exists.
## Installation
In your `Cargo.toml` add the following:
```toml
[features]
hot = ["dexterous_developer_example/hot", "bevy/dynamic_linking"]
[lib]
name = "lib_THE_NAME_OF_YOUR_GAME"
path = "src/lib.rs"
crate-type = ["rlib", "dylib"]
[dependencies]
bevy = "0.11"
dexterous_developer_example = "0.0.1"
serde = "1" # If you want the serialization capacities
```
If your game is not a library yet, move all your main logic to `lib.rs` rather than `main.rs`. Then, in your `main.rs`:
```rust
fn main() {
lib_THE_NAME_OF_YOUR_GAME::bevy_main(dexterous_developer::HotReloadOptions::default());
}
```
and in your `lib.rs`, your main function should become:
```rust
#[hot_bevy_main]
pub fn bevy_main(initial: InitialPlugins) {
App::new().add_plugins(initial.with_default_plugins()) // This should replace the "DefaultPlugins", and you can use ".set()" on these as well. Use "with_minimal_plugins()" if you don't want the defaults.
// ... and so on
}
```
If you have a plugin where you want to add reloadable elements, add the following in the file defining the plugin:
```rust
impl Plugin for MyPlugin {
fn build(&self, app: &mut App) {
app
.setup_reloadable_elements::<reloadable>();
}
}
#[dexterous_developer_setup]
fn reloadable(app: &mut ReloadableAppContents) {
app
.add_systems(Update, this_system_will_reload);
}
```
You might also want the following in your `.cargo/config.toml`:
```toml
# Add the contents of this file to `config.toml` to enable "fast build" configuration. Please read the notes below.
# NOTE: For maximum performance, build using a nightly compiler
# If you are using rust stable, remove the "-Zshare-generics=y" below.
[target.x86_64-unknown-linux-gnu]
linker = "clang"
rustflags = ["-Clink-arg=-fuse-ld=lld", "-Zshare-generics=y"]
# NOTE: you must install [Mach-O LLD Port](https://lld.llvm.org/MachO/index.html) on mac. you can easily do this by installing llvm which includes lld with the "brew" package manager:
# `brew install llvm`
[target.x86_64-apple-darwin]
rustflags = [
"-C",
"link-arg=-fuse-ld=/usr/local/opt/llvm/bin/ld64.lld",
"-Zshare-generics=y",
]
[target.aarch64-apple-darwin]
rustflags = [
"-C",
"link-arg=-fuse-ld=/opt/homebrew/opt/llvm/bin/ld64.lld",
"-Zshare-generics=y",
]
[target.x86_64-pc-windows-msvc]
linker = "rust-lld.exe"
rustflags = ["-Zshare-generics=n"]
# Optional: Uncommenting the following improves compile times, but reduces the amount of debug info to 'line number tables only'
# In most cases the gains are negligible, but if you are on macos and have slow compile times you should see significant gains.
#[profile.dev]
#debug = 1
# Enable a small amount of optimization in debug mode
[profile.dev]
opt-level = 1
# Enable high optimizations for dependencies (incl. Bevy), but not for our code:
[profile.dev.package."*"]
opt-level = 3
[profile.dev.package.gfx-backend-vulkan]
opt-level = 3
debug-assertions = false
```