GameRules class has a private field storing all types of game rules.

public class GameRules {
	//...
	private final TreeMap<String, GameRules.Value> rules = new TreeMap<>();
	//...
}

If I use access transformer to make it public then I can add a new game rule.

But in GameRuleCommand class:

public class GameRuleCommand {
   public static void register(CommandDispatcher<CommandSource> dispatcher) {
      LiteralArgumentBuilder<CommandSource> literalargumentbuilder = Commands.literal("gamerule").requires((p_198491_0_) -> {
         return p_198491_0_.hasPermissionLevel(2);
      });

      for(Entry<String, GameRules.ValueDefinition> entry : GameRules.getDefinitions().entrySet()) {
         literalargumentbuilder.then(Commands.literal(entry.getKey()).executes((p_198489_1_) -> {
            return queryRule(p_198489_1_.getSource(), entry.getKey());
         }).then(entry.getValue().getType().createArgument("value").executes((p_198490_1_) -> {
            return setRule(p_198490_1_.getSource(), entry.getKey(), p_198490_1_);
         })));
      }

      dispatcher.register(literalargumentbuilder);
   }

   //...
}

It reads all the game rule types and creates the command format structure. If I add the game rule after the command registered, the /gamerule command will not work on my custom game rule.

Edited March 10, 20196 yr by qouteall

You can do something like this:

private void doClientStuff(final FMLClientSetupEvent event)
{
  GameRules.getDefinitions().put("test", new GameRules.ValueDefinition("1", GameRules.ValueType.NUMERICAL_VALUE));
}

 

There's also a method in GameRules called setOrCreateGameRule, however that doesn't actually seem to create a gamerule, only sets the value, so that probably should only be used when setting the value, not creating the gamerule.

 

Quick tip: If you're trying to do something that vanilla already does (GameRules, Commands, etc...), look through the code and look at how vanilla does it, or just dig around the code and try to figure out how to solve your problem ?

It works. Thanks.