Mods4Kids

The idea of the project is the introduction of JAVA programming concepts through Minecraft mod programming. TBC

Minecraft introduction

• A Grownup's Guide to Minecraft and Writing Minecraft Mods - http://www.kegel.com/minecraft/
• Great Minecraft in-game tutorial series - How to Survive and Thrive https://www.youtube.com/watch?v=B36Ehzf2cxE&list=PL7326EF82122776A9
• Guide to how Minecraft works - http://greyminecraftcoder.blogspot.com.au/p/list-of-topics.html
• Forge Modding articles - http://www.wuppy29.com/minecraft/modding-tutorials/forge-modding-1-8
• Forge Tutorials listing - http://www.minecraftforge.net/forum/index.php/board,120.0.html
• General Forge notes - http://greyminecraftcoder.blogspot.co.uk/2013/12/forge-techniques-some-general-notes.html
• Minecraft By Example - https://github.com/TheGreyGhost/MinecraftByExample

Minecraft Forge

• Built oo top of MCP - Minecraft Coders Pack
• Use MCP to decompile the Minecraft client and server jar files.
• Use the decompiled source code to create mods for Minecraft.
• Recompile modified versions of Minecraft.
• Reobfuscate the classes of your mod for Minecraft.

Almost all mods nowadays use Forge. Supports both client and server mods. List of Forge API Events http://www.minecraftforge.net/wiki/Event_Reference

Spigot/Bukkit

Another way to mod Minecraft, but it's for server only mods. API not that powerful as Forge.

Installation

Prerequisites

• Programming language we will develop the mods: Java JDK 1.8 http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
  • try: java -version in a command line - there are chances that you have one already installed
• Programming environment: Idea IntelliJ Community Edition https://www.jetbrains.com/idea/download/#
• Modding platform: Minecraft Forge source package (MDK, recommended version, not the latest) http://files.minecraftforge.net

Environment Setup

This will do quite a lot of tasks: download most requirements (Minecraft, MCP (Mod Coder Pack), Java Libraries, Gradle, Forge, and FML). Set up Forge, with MCP and Gradle.

1. Install Java and IntelliJ

2. Create dev/minecraft folder in your home directory

3. Setup Minecraft Forge workspace (it might take more than 30 mins):

   • Copy minecraft-forge-mdk.zip to dev/minecraft and unzip it

   • rename it to coder-dojo-forge

   • In a command line console do:

         > cd [YOUR_HOME]/dev/minecraft/coder-dojo-forge
         > export JAVA_OPTS="-Xmx2g"
         > ./gradlew setupDecompWorkspace --refresh-dependencies --stacktrace
         > ./gradlew idea
     

4. Start IntelliJ and click Open Project and select dev/minecraft/coder-dojo-forge

   • build the project (setup SDK pointing to installed Java8 if IntelliJ doesn’t see it)
   • choose “MinecraftClient” from runtime configurations and click a run button

JAVA

The whole point of exercise is to sneak some programming concepts so as the part of the mods development we will have a Java sandbox project on the side to play with the following concepts:

• hello world
• static vs object methods
• class vs object scope
• startup arguments (task: print out all args passed to the program in the execution)
• string concatenation in output
• for loops
• collections: arrays, lists, sets, and basic operations (add, delete, contains, etc.)
• interface, inheritance (Animal.makeSound(), Cat, Dog), instanceof
• and more...

MODS

Preferably don’t give kids the code straight away, or maybe just a template, or the simple case, and ask them to run it and then modify regarding to your requests. Ask kids about their favorite mods, why they are special and meaningful to them?

Break Block Message

• explain how we can hack into the Minecraft, what are possibilities, etc (events, chaging blocks, physics, spawwning animals, executing commands, etc.)
• explain the idea of a EventBus and registration of event consumers
• run the client in debug mode and modify classes, changing implementation on the fly
• modifications:
  • make the message to be of GOLD color
  • make the message to show a type of the block destroyed

Super Jump + Parachute

• in a Java sandbox project create a simple hierarchy of Animals (Animal, Cat, Dog, Cow) making sounds to introduce concepts of inheritance, method overloading and type hierarchies
• based on EntityPlayer, show its type tree (or draw on paper)
• explain instanceof concept (in code: event.entity instanceof EntityPlayer)
• modifications
  • add chat message when jump starts with player’s initial position
  • experiment with height of a jump

Flaming pigs

• In Java sandbox project
  • command line arguments exercise
    • reading from input
    • print all incoming arguments out
    • parse string values into Integer
    • exceptions (ie. when parsing)
  • loops
    • 10 times printout “I love minecraft!"
  • create a list, add/remove/count elements, iterate through elements writing each one to std output
• explain: interfaces vs classes
• modifications
  • spawn flaming cows, chickens, zombies

Block Filler

Combination of Command and Event Handler. Create grids of blocks of any kind. Requires to use wooden axe to set up a position (left and right mouse button) (event handler), and invoking a command /fb block_id. Block ids reference: http://minecraft-ids.grahamedgecombe.com .

• In Java sandbox project
  • loops
    • loop over 3 variables
• modifications:
  • command to build a walled space, where you can put your spawn pigs