Dexterous Developer

An experimental hot reload system for the bevy game engine. Inspired by DGriffin91's 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 bevywinit (only when hot reload is enabled, will use the regular bevywinit otherwise). A PR for adding the required ability to bevy exists.

Installation

In your Cargo.toml add the following:

```toml [features] hot = ["dexterousdeveloperexample/hot", "bevy/dynamic_linking"]

[lib] name = "libTHENAMEOFYOUR_GAME" path = "src/lib.rs" crate-type = ["rlib", "dylib"]

[dependencies] bevy = "0.11" dexterousdeveloperexample = "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() { libTHENAMEOFYOURGAME::bevymain(dexterous_developer::HotReloadOptions::default()); }

```

and in your lib.rs, your main function should become:

```rust

[hotbevymain]

pub fn bevymain(initial: InitialPlugins) { App::new().addplugins(initial.withdefaultplugins()) // This should replace the "DefaultPlugins", and you can use ".set()" on these as well. Use "withminimalplugins()" 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 .setupreloadableelements::(); } }

[dexterousdevelopersetup]

fn reloadable(app: &mut ReloadableAppContents) { app .addsystems(Update, thissystemwillreload); }

```

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 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

```