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LDtk Rust Library

Crates.io Docs.rs

ldtk_rust enables access to LDtk data for use in Rust. LDtk is a 2D level editor for games that supports multiple tile layers, powerful auto-tiling rules, entity placement and more.

Status

This library works with LDtk version 1.1.3 and supports the optional external level files. LDtk updates save files automatically, so there's no reason to be on an older version, but if you are (or if you get a new version before this crate is updated) you can follow the process below to generate code against whatever LDtk version you want to use. Or if you'd like to not use ANY library and embed the code directly in your game, take a look at this process.

Getting Started

Calling the new() method on the LdtkFile struct with the path to a LDtk file will populate a struct that closely resembles the LDtk JSON format.

use ldtk_rust::Project;

fn main() {
    let ldtk = Project::new( "assets/test_game.ldtk");
    println!("First level pixel height is {}!", ldtk.levels[0].px_hei);
}

Your editor's auto-complete should help you visualize your options, or you can generate API docs with "cargo doc --open" or view them here.

Run the Examples

You can run the programs in the example folder using cargo:

> cargo run --example basic

Example dependencies do not load when compiling the library for production.

Using in a Real Game

An example running in Bevy Engine is included in the examples directory. There are lots of comments, and the focus of the example is on the process, not the Bevy-specific code. If you are using another game engine the example will hopefully still be understandable and useful.

Implementation Details

  • Use Project::new() to load all data, including any external level data. Use this if you want to load all your data at startup and you don't want to worry about whether level data is in separate files.

  • If you want to load one level at a time, see examples/single_level.rs. Essentially you will call Project::load_project() followed by Level::new() as you load each level.

  • The JSON deserialization is handled by serde using Rust code that is auto-generated from the LDtk JSON schema. In general this code matches the LDtk documentation except CamelCase names preferred in JSON are changed to snake_case names preferred in Rust. JSON types of String, Int and Float become Rust types of String, i64 and f64.

  • Fields that allow null values are wrapped in a Rust Option<T>

Other Options

  • ldtk-rs auto generates the entire crate from the JSON schema specified.

  • The LDtk project publishes QuickType loaders for a variety of languages. These are auto generated, so they might need adjusting a bit. Last time I tested the Rust version, I needed to tweak the serde line at the top.

  • Embed the JSON conversion in your game (removing any dependencies) by following the instructions below and reviewing the lib.rs file.

Using With Older or Newer Version of LDtk

LDtk includes a JSON schema that can be used to auto-generate RUST code to unmarshal the JSON.

To use this library with an older (or newer) version of the LDtk Schema:

  1. Clone this project
  2. Check the /src subdirectory to see if there is already auto-generated code for the version you want to use. If so, skip to #7 below. If not, you're going to create a new file for the version you want to use.
  3. Copy the version of the Schema file from the LDtk Github that corresponds to your version and paste it into the quicktype web tool. The Schema is in the docs/ directory.
  4. On the left, set the "name" to "Project" and the "Source type" to "JSON Schema"
  5. On the right choose the Rust language and set field visibility to "Public".
  6. Save the resulting file to the /src subdirectory of this project
  7. Change the serde import line near the top of the file to "use serde::*;". You can view the other .rs version files to see this.
  8. Change the mod and pub use lines at the top of lib.rs (in the same directory you're working in already) to include your new file instead.

You'll need to adjust your Cargo.toml file to use your project instead of this one (or contribute your change back here).

How To Not Use This Library

Take a look at lib.rs and decide if you really even want this project wrapping the autogenerated code, or if you want to just include it in your own project directly. As LDtk nears 1.0 the JSON Schema is getting better, and using this process has become easier. To do this:

  1. Do the QuickType stuff in the instructions above (steps #3-5).
  2. Copy and save the resulting Rust code to a file in your project.
  3. Change the serde import line at the top (step #7 above).
  4. Include this file in your project and have fun! You can review the lib.rs file in this project to see how it's included and used.