Bevy YOLECK - Your Own Level Editor Creation Kit

Yoleck is a crate for having a game built with the Bevy game engine act as its own level editor.

Features

• Same executable can launch in either game mode or editor mode, depending on the plugins added to the app.
• Write systems that create entities based on serializable structs - use same systems for both loading the levels and visualizing them in the editor.
• Entity editing is done with egui widgets that edit these structs.
• Support for external plugins that offer more visual editing.
  • One simple such plugin - Vpeol is included in the crate. It provides basic entity selection, positioning with mouse dragging, and basic camera control. It has two variants behind feature flags - vpeol_2d and vpeol_3d.
• A knobs mechanism for more visual editing.
• Playtest the levels inside the editor.
• Multiple entity selection in the editor with the Shift key.

Examples:

• WASM examples - you can't save the levels because it's WASM, but you can edit the levels run playtests:

  • 2D editor: https://idanarye.github.io/bevy-yoleck/demos/example2d

    https://user-images.githubusercontent.com/1149255/228007948-31a37b3f-7bd3-4a36-a3bc-4617d359c7c2.mp4

  • 3D editor: https://idanarye.github.io/bevy-yoleck/demos/example3d

    https://user-images.githubusercontent.com/1149255/228008014-825ef02e-2edc-49f5-a15c-1fa6044f84de.mp4

  • Loading multiple levels and unloading them on the fly: https://idanarye.github.io/bevy-yoleck/demos/doors_to_other_levels

    https://github.com/idanarye/bevy-yoleck/assets/1149255/590beba4-2ca5-4218-af52-143321bb5946

    The WASM version of this example is gameplay only. To see how the editor for it looks like, clone/download the repository and run:

    cargo run --example doors_to_other_levels --features vpeol_2d,bevy/png
    

• Example game:
  • Download binaries from https://aeon-felis.itch.io/danger-doofus
  • See the code at https://github.com/idanarye/sidekick-jam-entry-danger-doofus
  • Run the exeutable with --editor to edit the game levels with Yoleck.

File Format

Yoleck saves the levels in JSON files that have the .yol extension. A .yol file's top level is a tuple (actually JSON array) of three values:

• File metadata - e.g. Yoleck version.
• Level data (placeholder - currently an empty object)
• List of entities.

Each entity is a tuple of two values:

• Entity metadata - e.g. its type.
• Entity componments - that's the user defined structs.

The reason tuples are used instead of objects is to ensure ordering - to guarantee the metadata can be read before the data. This is important because the metadata is needed to parse the data.

Yoleck generates another JSON file in the same directory as the .yol files called index.yoli. The purpose of this file is to let the game know what level are available to it (in WASM, for example, the asset server cannot look at a directory's contents). The index file contains a tuple of two values:

• Index metadata - e.g. Yoleck version.
• List of objects, each contain a path to a level file relative to the index file.

Versions

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

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.