Kotlin extensions for libGDX.
Introduction
KTX is a Kotlin game framework built on libGDX. It aims to make libGDX as Kotlin-friendly as possible without completely rewriting the API. It provides modular utilities and extensions for selected parts of libGDX with poor Kotlin support.
Examples of Kotlin language features used to improve usability, performance, and readability of libGDX include:
- Operator overloads for collections and mathematical operations.
- Extension methods improving original libGDX APIs without the use of inheritance.
- Inline methods with reduced runtime overhead for various listeners, builders, and loggers.
- Nullable types which improve typing information of selected interfaces and functions.
- Default parameters reducing boilerplate code.
- Type-safe builders for GUI, styling, and physics engine.
- Default interface methods for common interfaces, simplifying their implementations.
- Coroutines context providing concurrency utilities and non-blocking asset loading.
- Reified types that simplify usage of methods normally consuming
Class
parameters.
See the Choosing KTX article for pros and cons of this framework.
Modules
KTX was designed to be modular from day one - in fact, many of its libraries are just a single Kotlin file. You can include selected KTX modules based on the needs of your application.
Module | Description |
---|---|
ktx-actors |
Scene2D GUI extensions for stages, actors, actions, and event listeners. |
ktx-app |
ApplicationListener implementations and general application utilities. |
ktx-ashley |
Ashley entity-component-system utilities. |
ktx-assets |
Resources management utilities. |
ktx-assets-async |
Non-blocking asset loading using coroutines. |
ktx-async |
Coroutines context based on libGDX threading model. |
ktx-box2d |
Box2D physics engine utilities. |
ktx-collections |
Extensions for libGDX custom collections. |
ktx-freetype |
FreeType fonts loading utilities. |
ktx-freetype-async |
Non-blocking FreeType fonts loading using coroutines. |
ktx-graphics |
Utilities related to rendering tools and graphics. |
ktx-i18n |
Internationalization API utilities. |
ktx-inject |
A dependency injection system with low overhead and no reflection usage. |
ktx-json |
Utilities for libGDX JSON serialization API. |
ktx-log |
Minimal runtime overhead cross-platform logging using inlined functions. |
ktx-math |
Operator functions for libGDX math API and general math utilities. |
ktx-preferences |
Improved API for accessing and saving preferences. |
ktx-reflect |
Utilities for libGDX reflection API. |
ktx-scene2d |
Type-safe Kotlin builders for Scene2D GUI. |
ktx-style |
Type-safe Kotlin builders for Scene2D widget styles extending Skin API. |
ktx-tiled |
Utilities for Tiled maps. |
ktx-vis |
Type-safe Kotlin builders for VisUI . |
ktx-vis-style |
Type-safe Kotlin builders for VisUI widget styles. |
Installation
KTX modules are uploaded to Maven Central and are fully compatible with the Gradle build tool, which is used in libGDX projects by default.
All libraries follow the same naming schema:
api "io.github.libktx:$module:$ktxVersion"
Replace $module
with the name of the selected KTX library (see the table above).
For example, including the app module with the ktx-app
identifier would require the following changes in your build.gradle
file:
// Groovy DSL:
ext {
// Update this version to match the latest KTX release:
ktxVersion = '1.10.0-b4'
}
dependencies {
api group: 'io.github.libktx', name: 'ktx-app', version: ktxVersion
}
// Kotlin DSL:
// Update this version to match the latest KTX release:
val ktxVersion = "1.10.0-b4"
dependencies {
api(group = "io.github.libktx", name = "ktx-app", version = ktxVersion)
}
You can find the latest KTX version on Maven Central:
KTX modules should generally be added to the dependencies of the shared core
module of your libGDX application.
As a side note, defining
ktxVersion
as a property inext
is not necessary, as versions can be set directly in thedependencies
section. However, extracting the dependencies versions is a good practice, especially if they can be reused throughout the build files. This will speed up updating of your project if you include multiple KTX modules.
Versioning
KTX versions match the libGDX versions that they were compiled against. $ktxVersion
will usually match your libGDX version, but it might end with -b
postfix if it is a beta release, or -SNAPSHOT
if you are using the development branch.
You can browse through our official releases on Maven and on GitHub.
Unfortunately, libGDX does not follow the semantic versioning guidelines. Both minor and patch versions can introduce breaking changes. Please read the libGDX and KTX change logs before updating.
Although KTX still uses beta release tags, the official releases are stable enough for production use. All modules are thoroughly tested with unit tests.
Latest changes
The master
branch is the default branch of the repository. It represents the latest stable release of KTX. It ensures that the documentation in the repository is in sync with the latest version.
The newest changes can be found on the develop
branch instead.
You do not have to compile the sources manually to use the latest features. The preview snapshot releases are uploaded to the https://oss.sonatype.org/content/repositories/snapshots/
repository. To use them in your application, add the following Maven repository, and modify the prefix of ktxVersion
to -SNAPSHOT
:
// Groovy DSL:
repositories {
// Include your other repositories here.
maven { url 'https://oss.sonatype.org/content/repositories/snapshots/' }
}
ext {
// Update this version to match the latest libGDX release:
ktxVersion = '1.10.0-SNAPSHOT'
}
// Kotlin DSL:
repositories {
// Include your other repositories here.
maven("https://oss.sonatype.org/content/repositories/snapshots/")
}
// Update this version to match the latest libGDX release:
val ktxVersion = "1.10.0-SNAPSHOT"
The latest snapshot version name can be found on the develop
branch.
Even the snapshots are rather stable, as the libraries are not pushed to Maven Central unless they pass their extensive test suites. However, the public APIs in snapshot releases might be changed prior to a stable release.
Documentation
Official guides
Each module contains a README.md
file with a list of all its features and a guide with useful code snippets. Browse through the directories in the root folder to find out more about each library.
Source documentation
All functionalities are documented with Kotlin KDocs. You can access the source documentation by:
- Viewing the generated Dokka files hosted on the project website.
- Extracting the
doc
folders with Dokka files from release archives. - Reading the sources directly.
Links
KTX wiki lists some useful resources that can help you get started.
Most official guides and code examples in this repository assume that the reader is at least a bit familiar with the libGDX API. If you are just getting to know the framework, it might be helpful to go through the official libGDX wiki, and convert some Java examples to Kotlin.
Contribution
Suggestions, questions, typo fixes, documentation improvements and code contributions are always welcome.
Do not hesitate to start a discussion with questions about the framework. Feel free to advertise your KTX project, propose new features, discuss game jams, or even create a personal devlog.
If you would like to contribute, please read the contribution guideline, and browse through the active issues. The develop
is the active development branch. When creating pull requests, make sure to choose develop
as the target branch.
You can check the list of the contributors via GitHub insights and on the contributors list.
Licensing
This project is dedicated to public domain.
Working from sources
See this section of the contribution guideline to get started.