The KK Physics Project is about integrating the Jolt Physics engine into the jMonkeyEngine (JME) game engine.

This project is currently a proof of concept and is not intended for production use.

It contains 2 subprojects:

1. library: the KK Physics JVM runtime library
2. apps: non-automated test software

Complete source code (in Java) is provided under a 3-clause BSD license.

Contents of this document

• How to add KK Physics to an existing project
• How to build KK Physics from source
• External links
• Acknowledgments

How to add KK Physics to an existing project

KK Physics comes pre-built as a single library that depends on the standard "jme3-core" library from jMonkeyEngine.

For projects built using Maven or Gradle, it is sufficient to add dependencies on the KK Physics library and the jolt-java Linux native library. The build tool should automatically resolve the remaining dependencies.

Gradle-built projects

Add to the project’s "build.gradle" file:

repositories {
    mavenCentral()
}
dependencies {
    implementation 'com.github.stephengold:kk-physics:0.1.0'
    runtimeOnly 'com.github.stephengold:jolt-java-natives-linux-x86:0.1.0'
}

For some older versions of Gradle, it's necessary to replace implementation with compile.

Maven-built projects

Add to the project’s "pom.xml" file:

<repositories>
  <repository>
    <id>mvnrepository</id>
    <url>https://repo1.maven.org/maven2/</url>
  </repository>
</repositories>

<dependency>
  <groupId>com.github.stephengold</groupId>
  <artifactId>kk-physics</artifactId>
  <version>0.1.0</version>
</dependency>
<dependency>
  <groupId>com.github.stephengold</groupId>
  <artifactId>jolt-java-natives-linux-x86</artifactId>
  <version>0.1.0</version>
</dependency>

How to build KK Physics from source

1. Install a Java 19 Development Kit (JDK), if you don't already have one.
2. Point the JAVA_HOME environment variable to your JDK installation: (In other words, set it to the path of a directory/folder containing a "bin" that contains a Java executable. That path might look something like "C:\Program Files\Eclipse Adoptium\jdk-19.0.3.7-hotspot" or "/usr/lib/jvm/java-19-openjdk-amd64/" or "/Library/Java/JavaVirtualMachines/zulu-19.jdk/Contents/Home" .)

• using Bash or Zsh: export JAVA_HOME=" path to installation "
• using Fish: set -g JAVA_HOME " path to installation "
• using Windows Command Prompt: set JAVA_HOME=" path to installation "
• using PowerShell: $env:JAVA_HOME = ' path to installation '

3. Download and extract the KK Physics source code from GitHub:

• using Git:
  • git clone https://github.com/stephengold/kk-physics.git
  • cd kk-physics
  • git checkout -b latest 0.1.0

4. Run the Gradle wrapper:

• using Bash or Fish or PowerShell or Zsh: ./gradlew build
• using Windows Command Prompt: .\gradlew build

After a successful build, Maven artifacts will be found in "library/build/libs".

You can install the artifacts to your local Maven repository:

• using Bash or Fish or PowerShell or Zsh: ./gradlew install
• using Windows Command Prompt: .\gradlew install

You can restore the project to a pristine state:

• using Bash or Fish or PowerShell or Zsh: ./gradlew clean
• using Windows Command Prompt: .\gradlew clean

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External links

• Jolt Physics Multicore Scaling (2022)
• Architecting Jolt Physics (2022), also in a different form here
• Minie, a similar project that integrates Bullet Physics into jMonkeyEngine
• The physics section of the jMonkeyEngine Wiki (2020)
• Alan Chou's game-physics tutorial (2013)

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History

The API and much of the source code is derived from Minie.

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Acknowledgments

Like most projects, the KK Physics Project builds on the work of many who have gone before. I therefore acknowledge the following software developers:

• "aecsocket" for creating the jolt-java bindings to the Jolt Physics Engine
• Normen Hansen (aka "normen") for creating most of the jme3-bullet library (from which the KK Physics API is derived)
• plus the creators of (and contributors to) the following software:
  • the Firefox web browser
  • the Git revision-control system and GitK commit viewer
  • the GitKraken client
  • the Gradle build tool
  • the Java compiler, standard doclet, and runtime environment
  • jMonkeyEngine and the jME3 Software Development Kit
  • the Jolt Physics Engine
  • the Linux Mint operating system
  • LWJGL, the Lightweight Java Game Library
  • the Markdown document-conversion tool
  • the Meld visual merge tool
  • the NetBeans integrated development environment

I am grateful to GitHub and Sonatype for providing free hosting for this project and many other open-source projects.

I'm also grateful to my dear Holly, for keeping me sane.

If I've misattributed anything or left anyone out, please let me know, so I can correct the situation: [email protected]

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